Comparison of metabolic effects of pioglitazone, metformin, and glimepiride over 1 year in Japanese patients with newly diagnosed Type 2 diabetes

Certain sulfonylurea drugs increase serum free fatty acid in diabetic patients: A systematic review and meta-analysis

BACKGROUND

Sulfonylurea (SU) is a commonly used antidiabetic drugs effective for type 2 diabetes mellitus. Previous studies have reported that the SU treatment could alter the serum free fatty acid (FFA) concentration in diabetic patients; however, their exact effects remain unknown.

AIM

To assess the impact of SU on the FFA level in diabetic patients.

METHODS

A systematic literature search was conducted by consulting the PubMed, EMBASE, Cochrane Library, Reference Citation Analysis (https://www.referencecitationanalysis.com/), and Web of Science databases from January 1, 1991 to July 30, 2021. Either a fixed-effects model or random-effects model was applied to study the association between SU treatment and FFA concentration according to the heterogeneity test. Two investigators independently performed data extraction. The mean difference (MD) and corresponding 95% confidence interval (CI) were used to measure effect size. R3.5.1 software was utilized for conducting statistical analyses.

RESULTS

A total of 13 studies with 2273 individuals were selected. Results indicated that FFA concentration increased slightly after treatment with SU (MD = 0.08, 95%CI: 0.03-0.12, P < 0.01). In addition, we found that SU treatment combined with other antidiabetics could also increase the concentration of serum FFA (MD = 0.14, 95%CI: 0.01-0.28, P < 0.01). Regarding the type of SU, there was no significant difference in FFA concentration with glimepiride or glibenclamide. FFA concentration was higher at ≥ 12 wk (MD = 0.09, 95%CI: 0.04-0.13) but not at < 12 wk (MD = 0.01, 95%CI: -0.07-0.09).

CONCLUSION

SU treatment could increase the serum FFA concentration in diabetic patients. The fundamental underlying mechanism still needs further investigation.

Metformin and health outcomes: An umbrella review of systematic reviews with meta-analyses

BACKGROUND

The objective was to capture the breadth of outcomes that have been associated with metformin use and to systematically assess the quality, strength and credibility of these associations using the umbrella review methodology.

METHODS

Four major databases were searched until 31 May 2020. Meta-analyses of observational studies and meta-analyses of randomized controlled trials (RCTs) (including active and placebo control arms) were included.

RESULTS

From 175 eligible publications, we identified 427 different meta-analyses, including 167 meta-analyses of observational studies, 147 meta-analyses of RCTs for metformin vs placebo/no treatment and 113 meta-analyses of RCTs for metformin vs active medications. There was no association classified as convincing or highly suggestive from meta-analyses of observational studies, but some suggestive/weak associations of metformin use with a lower mortality risk of CVD and cancer. In meta-analyses of RCTs, metformin was associated with a lower incidence of diabetes in people with prediabetes or no diabetes at baseline; lower ovarian hyperstimulation syndrome incidence (in women in controlled ovarian stimulation); higher success for clinical pregnancy rate in poly-cystic ovary syndrome (PCOS); and significant reduction in body mass index in people with type 1 diabetes mellitus, in women who have obesity/overweight with PCOS and in obese/overweight women. Of 175 publications, 166 scored as low or critically low quality per AMSTAR 2 criteria.

CONCLUSIONS

Observational evidence on metformin seems largely unreliable. Randomized evidence shows benefits for preventing diabetes and in some gynaecological and obstetrical settings. However, almost all meta-analyses are of low or critically low quality according to AMSTAR 2 criteria.

Review of methods for detecting glycemic disorders

Prediabetes (intermediate hyperglycemia) consists of two abnormalities, impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) detected by a standardized 75-gram oral glucose tolerance test (OGTT). Individuals with isolated IGT or combined IFG and IGT have increased risk for developing type 2 diabetes (T2D) and cardiovascular disease (CVD). Diagnosing prediabetes early and accurately is critical in order to refer high-risk individuals for intensive lifestyle modification. However, there is currently no international consensus for diagnosing prediabetes with HbA1c or glucose measurements based upon American Diabetes Association (ADA) and the World Health Organization (WHO) criteria that identify different populations at risk for progressing to diabetes. Various caveats affecting the accuracy of interpreting the HbA1c including genetics complicate this further. This review describes established methods for detecting glucose disorders based upon glucose and HbA1c parameters as well as novel approaches including the 1-hour plasma glucose (1-h PG), glucose challenge test (GCT), shape of the glucose curve, genetics, continuous glucose monitoring (CGM), measures of insulin secretion and sensitivity, metabolomics, and ancillary tools such as fructosamine, glycated albumin (GA), 1,5- anhydroglucitol (1,5-AG). Of the approaches considered, the 1-h PG has considerable potential as a biomarker for detecting glucose disorders if confirmed by additional data including health economic analysis. Whether the 1-h OGTT is superior to genetics and omics in providing greater precision for individualized treatment requires further investigation. These methods will need to demonstrate substantially superiority to simpler tools for detecting glucose disorders to justify their cost and complexity.

Metformin monotherapy for adults with type 2 diabetes mellitus

BACKGROUND

Worldwide, there is an increasing incidence of type 2 diabetes mellitus (T2DM). Metformin is still the recommended first-line glucose-lowering drug for people with T2DM. Despite this, the effects of metformin on patient-important outcomes are still not clarified.

OBJECTIVES

To assess the effects of metformin monotherapy in adults with T2DM.

SEARCH METHODS

We based our search on a systematic report from the Agency for Healthcare Research and Quality, and topped-up the search in CENTRAL, MEDLINE, Embase, WHO ICTRP, and ClinicalTrials.gov. Additionally, we searched the reference lists of included trials and systematic reviews, as well as health technology assessment reports and medical agencies. The date of the last search for all databases was 2 December 2019, except Embase (searched up 28 April 2017).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) with at least one year's duration comparing metformin monotherapy with no intervention, behaviour changing interventions or other glucose-lowering drugs in adults with T2DM.

DATA COLLECTION AND ANALYSIS

Two review authors read all abstracts and full-text articles/records, assessed risk of bias, and extracted outcome data independently. We resolved discrepancies by involvement of a third review author. For meta-analyses we used a random-effects model with investigation of risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. We assessed the overall certainty of the evidence by using the GRADE instrument.

MAIN RESULTS

We included 18 RCTs with multiple study arms (N = 10,680). The percentage of participants finishing the trials was approximately 58% in all groups. Treatment duration ranged from one to 10.7 years. We judged no trials to be at low risk of bias on all 'Risk of bias' domains. The main outcomes of interest were all-cause mortality, serious adverse events (SAEs), health-related quality of life (HRQoL), cardiovascular mortality (CVM), non-fatal myocardial infarction (NFMI), non-fatal stroke (NFS), and end-stage renal disease (ESRD). Two trials compared metformin (N = 370) with insulin (N = 454). Neither trial reported on all-cause mortality, SAE, CVM, NFMI, NFS or ESRD. One trial provided information on HRQoL but did not show a substantial difference between the interventions. Seven trials compared metformin with sulphonylureas. Four trials reported on all-cause mortality: in three trials no participant died, and in the remaining trial 31/1454 participants (2.1%) in the metformin group died compared with 31/1441 participants (2.2%) in the sulphonylurea group (very low-certainty evidence). Three trials reported on SAE: in two trials no SAE occurred (186 participants); in the other trial 331/1454 participants (22.8%) in the metformin group experienced a SAE compared with 308/1441 participants (21.4%) in the sulphonylurea group (very low-certainty evidence). Two trials reported on CVM: in one trial no CVM was observed and in the other trial 4/1441 participants (0.3%) in the metformin group died of cardiovascular reasons compared with 8/1447 participants (0.6%) in the sulphonylurea group (very low-certainty evidence). Three trials reported on NFMI: in two trials no NFMI occurred, and in the other trial 21/1454 participants (1.4%) in the metformin group experienced a NFMI compared with 15/1441 participants (1.0%) in the sulphonylurea group (very low-certainty evidence). One trial reported no NFS occurred (very low-certainty evidence). No trial reported on HRQoL or ESRD. Seven trials compared metformin with thiazolidinediones (very low-certainty evidence for all outcomes). Five trials reported on all-cause mortality: in two trials no participant died; the overall RR was 0.88, 95% CI 0.55 to 1.39; P = 0.57; 5 trials; 4402 participants). Four trials reported on SAE, the RR was 0,95, 95% CI 0.84 to 1.09; P = 0.49; 3208 participants. Four trials reported on CVM, the RR was 0.71, 95% CI 0.21 to 2.39; P = 0.58; 3211 participants. Three trial reported on NFMI: in two trials no NFMI occurred and in one trial 21/1454 participants (1.4%) in the metformin group experienced a NFMI compared with 25/1456 participants (1.7%) in the thiazolidinedione group. One trial reported no NFS occurred. No trial reported on HRQoL or ESRD. Three trials compared metformin with dipeptidyl peptidase-4 inhibitors (one trial each with saxagliptin, sitagliptin, vildagliptin with altogether 1977 participants). There was no substantial difference between the interventions for all-cause mortality, SAE, CVM, NFMI and NFS (very low-certainty evidence for all outcomes). One trial compared metformin with a glucagon-like peptide-1 analogue (very low-certainty evidence for all reported outcomes). There was no substantial difference between the interventions for all-cause mortality, CVM, NFMI and NFS. One or more SAEs were reported in 16/268 (6.0%) of the participants allocated to metformin compared with 35/539 (6.5%) of the participants allocated to a glucagon-like peptide-1 analogue. HRQoL or ESRD were not reported. One trial compared metformin with meglitinide and two trials compared metformin with no intervention. No deaths or SAEs occurred (very low-certainty evidence) no other patient-important outcomes were reported. No trial compared metformin with placebo or a behaviour changing interventions. Four ongoing trials with 5824 participants are likely to report one or more of our outcomes of interest and are estimated to be completed between 2018 and 2024. Furthermore, 24 trials with 2369 participants are awaiting assessment.

AUTHORS' CONCLUSIONS

There is no clear evidence whether metformin monotherapy compared with no intervention, behaviour changing interventions or other glucose-lowering drugs influences patient-important outcomes.

The Phantom of Metformin-Induced Lactic Acidosis in End-Stage Renal Disease Patients: Time to Reconsider with Peritoneal Dialysis Treatment

Objective

Metformin continues to be the safest and most widely used antidiabetic drug. In spite of its well-known benefits; metformin use in end-stage renal disease (ESRD) patients is still restricted. Little has been reported about the effect of peritoneal dialysis (PD) on metformin clearance and the phantom of lactic acidosis deprives ESRD patients from metformin therapeutic advantages. Peritoneal dialysis is probably a safeguard against lactic acidosis, and it is likely that using this drug would be feasible in this group of patients.

Material and methods

The study was conducted on 83 PD patients with type 2 diabetes mellitus. All patients were on automated PD (APD). Metformin was administered in a dose of 500 - 1,000 mg daily. Patients were monitored for glycemic control. Plasma lactic acid and plasma metformin levels were monitored on a scheduled basis. Peritoneal fluid metformin levels were measured. In addition, the relation between plasma metformin and plasma lactate was studied.

Results

Mean fasting blood sugar (FBS) was 10.9 ± 0.5 and 7.8 ± 0.7, and mean hemoglobin A1-C (HgA1C) was 8.2 ± 0.8 and 6.4 ± 1.1 at the beginning and end of the study, respectively (p < 0.001). The mean body mass index (BMI) was 29.1 ± 4.1 and 27.3 ± 4.5 at the beginning and at the end of the study, respectively (p < 0.001). The overall mean plasma lactate level across all blood samples was 1.44 ± 0.6. Plasma levels between 2 and 3 mmol/L were found in 11.8% and levels of 3 - 3.6 mmol/L in 2.4% plasma samples. Hyperlactemia (level > 2 and < 5 mmol/L) was not associated with overt acidemia. None of our patients had lactic acidosis (levels > 5 mmol/L). Age ≥ 60 was a predictor for hyperlactemia. No relationship was found between plasma metformin and lactate levels.

Conclusion

Metformin may be used with caution in a particular group of ESRD patients who are on APD. Metformin allows better diabetic control with significant reduction of BMI. Information on the relationship between metformin and plasma lactate levels is lacking. Peritoneal dialysis appears to be a safeguard against the development of lactic acidosis in this group of patients.

Efficacy and Safety of Pioglitazone Monotherapy in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Pioglitazone, the only thiazolidinedione drug in clinical practice is under scrutiny due to reported adverse effects, it's unique insulin sensitising action provides rationale to remain as a therapeutic option for managing type 2 diabetes mellitus (T2DM). We conducted a systematic review and meta-analysis comparing pioglitazone monotherapy with monotherapies of other oral antidiabetic drugs for assessing its efficacy and safety in T2DM patients. Mean changes in glycated haemoglobin (HbA1c), and mean changes in fasting blood sugar (FBS) level, body weight (BW) and homeostasis model assessment-insulin resistance (HOMA-IR) were primary and secondary outcomes, respectively. Safety outcomes were changes in lipid parameters, blood pressure and incidences of adverse events. Metafor package of R software and RevMan software based on random-effects model were used for analyses. We included 16 randomised controlled trials. Pioglitazone monotherapy showed equivalent efficacy as comparators in reducing HbA1c by 0.05% (95% CI: -0.21 to 0.11) and greater efficacy in reducing FBS level by 0.24 mmol/l (95% CI: -0.48 to -0.01). Pioglitazone showed similar efficacy as comparators in reducing HOMA-IR (WMD: 0.05, 95% CI: -0.49 to 0.59) and increasing high-density lipoprotein level (WMD: 0.02 mmol/l, 95% CI: -0.06 to 0.10). Improved blood pressure (WMD: -1.05 mmHg, 95% CI: -4.29 to 2.19) and triglycerides level (WMD: -0.71 mmol/l, 95% CI: -1.70 to 0.28) were also observed with pioglitazone monotherapy. There was a significant association of pioglitazone with increased BW (WMD: 2.06 kg, 95% CI: 1.11 to 3.01) and risk of oedema (RR: 2.21, 95% CI: 1.48 to 3.31), though the risk of hypoglycaemia was absolutely lower (RR: 0.51, 95% CI: 0.33 to 0.80). Meta-analysis supported pioglitazone as an effective treatment option for T2DM patients to ameliorate hyperglycaemia, adverse lipid metabolism and blood pressure. Pioglitazone is suggested to prescribe following individual patient's needs. It can be a choice of drug for insulin resistant T2DM patients having dyslipidaemia, hypertension or history of cardiovascular disease.

Failure of monotherapy in clinical practice in patients with type 2 diabetes: The Korean National Diabetes Program

AIMS/INTRODUCTION

We investigated the failure of monotherapy in patients with type 2 diabetes mellitus in real practice settings.

MATERIALS AND METHODS

The Korean National Diabetes Program was a prospective, multicenter observational cohort study of type 2 diabetes mellitus patients in Korea. Of the 3,950 patients enrolled in the study, we studied 998 who were continuously maintained on monotherapy for at least 90 days at six participating centers. To balance the baseline characteristics of patients in each group, we used propensity matching at a 1:1 ratio (metformin vs sulfonylureas) and 4:1 ratio (metformin vs meglitinides and metformin vs alpha-glucosidase inhibitors [aGIs]). The hazard ratios (HRs) of treatments (compared with metformin) were determined by Cox's proportional hazards regression modeling.

RESULTS

The median follow-up time was 56 months, and monotherapy failed in 45% of all patients. The annual incidences of failure were 15.6%, 21.3%, 27% and 9.6% in the metformin, sulfonylurea, meglitinide and aGI groups. Compared with metformin, sulfonylureas and meglitinides were associated with higher risks of monotherapy failure (HR 1.39, 95% confidence interval [CI] 1.08-1.80; HR 1.92, 95% CI 1.13-3.27), and aGIs with risks similar to that of metformin (HR 0.80, 95% CI 0.44-1.45). When analyzed by failure type, sulfonylureas, meglitinides and aGIs were associated with a higher risk of a switch to other agents (HR 4.43, 95% CI 2.14-9.17; HR 18.80, 95% CI 6.21-56.93; HR 4.25, 95% CI 1.49-12.13), and aGIs with a lower risk of prescription of add-on second agents (HR 0.16, 95% CI 0.04-0.64).

CONCLUSIONS

Metformin was associated with a lower failure risk than were sulfonylureas and meglitinides, but a comparable aGI failure rate.

Comparison of Pioglitazone and Metformin Efficacy against Glucocorticoid Induced Atherosclerosis and Hepatic Steatosis in Insulin Resistant Rats

INTRODUCTION

Insulin Resistance is a major cause of Atherosclerosis (AS) and Non Alcoholic Fatty Liver Disease (NAFLD). These lipid alterations in blood vessels and liver may progress to cardiovascular abnormalities and cirrhosis respectively. Drugs like pioglitazone (PIO) and metformin (MET) are effective insulin sensitizers used in T2DM. But their efficacy and tolerability needs to be compared in IR associated abnormalities.

AIM

To compare the efficacy of PIO and MET in glucocorticoid induced AS, Hepatic Steatosis (HS) and IR in albino rats.

MATERIALS AND METHODS

Male Wistar albino rats were randomized into four groups (n=6). Group 1 (Normal control) rats consumed 2% gum acacia orally for 12 days. Group 2 {dexamethasone (DEX) control} rats were administered 2% gum acacia orally for 12 days and DEX (8 mg/kg) intraperitoneally (i.p.) from 7th to 12th day during the study period. Group 3 and 4 (PIO and MET control) rats received oral administration of PIO (45 mg/kg) and MET (1000 mg/kg) for 12 days respectively. Both groups were treated with DEX (8 mg/kg/i.p.) from 7th to 12th day during the study period. On last day, fasting blood was collected and rats were sacrificed by cervical dislocation; aorta and liver tissues were isolated for the histopathological examination. Body weight, liver weight and liver volume were measured. Blood samples were processed for biochemical parameters. The data were analysed by One-way Analysis of variance (ANOVA) followed by Scheffe's multiple comparison post-hoc test. The statistical significance was assumed at p<0.05.

RESULTS

Our results established the possible role of DEX in the development of AS and HS. Histopathological examination of Group 2 rats treated with DEX showed a marked lipid accumulation in the aorta and liver. Administration of MET and PIO resulted in partial to complete restoration of DEX induced fatty changes in aorta and liver. Both drugs significantly (p<0.05) prevented the elevation of insulin, lipid, glucose levels, liver weight and liver volume in DEX treated rats. They had significantly (p<0.05) improved body weight and insulin sensitivity. However, PIO was highly significant (p<0.05) compared to MET in reducing DEX induced IR complications.

CONCLUSION

These findings suggest that PIO was more effective insulin sensitizer compared to MET in reducing AS, HS and IR induced by glucocorticoids.

Thiazolidinedione drugs in the treatment of type 2 diabetes mellitus: past, present and future

Thiazolidinedione (TZD) drugs used in the treatment of type 2 diabetes mellitus (T2DM) have proven effective in improving insulin sensitivity, hyperglycemia, and lipid metabolism. Though well tolerated by some patients, their mechanism of action as ligands of peroxisome proliferator-activated receptors (PPARs) results in the activation of several pathways in addition to those responsible for glycemic control and lipid homeostasis. These pathways, which include those related to inflammation, bone formation, and cell proliferation, may lead to adverse health outcomes. As treatment with TZDs has been associated with adverse hepatic, cardiovascular, osteological, and carcinogenic events in some studies, the role of TZDs in the treatment of T2DM continues to be debated. At the same time, new therapeutic roles for TZDs are being investigated, with new forms and isoforms currently in the pre-clinical phase for use in the prevention and treatment of some cancers, inflammatory diseases, and other conditions. The aims of this review are to provide an overview of the mechanism(s) of action of TZDs, a review of their safety for use in the treatment of T2DM, and a perspective on their current and future therapeutic roles.

A Novel Bongkrekic Acid Analog-Mediated Modulation of the Size of Lipid Droplets: Evidence for the Appearance of Smaller Adipocytes

Thiazolidinediones (TZDs) are known as peroxisome proliferator-activated receptor γ (PPARγ) activators, and are used in the treatment of diabetes. Although the usefulness of TZDs has been demonstrated, some of their side effects are becoming an obstacle to their clinical applicability; edema is known to be evoked by the "structural characteristics" of TZD, but not by the PPARγ activation. Thus, novel therapeutic modalities (i.e., non-TZD-type PPARγ activators) having different structures to those of TZDs are desired. We previously identified bongkrekic acid (BKA) as a PPARγ activator using the human breast cancer MCF-7 cell line as a model system. In the present study, we newly synthesized BKA analogs and examined the usefulness of BKA and its analogs as PPARγ activators in differentiated adipocyte cells. Among the chemicals investigated, one of the BKA analogs (BKA-#2) strongly stimulated PPARγ and the differentiation of 3T3-L1 cells similar to pioglitazone, a positive control. Furthermore, BKA-#2 reduced the size of lipid droplets in the mature adipocyte cells. The possible modulation mechanism by BKA-#2 is discussed.

Regulation of brown fat by AMP-activated protein kinase

Novel strategies are needed to reduce the obesity epidemic. One promising strategy is activation of brown adipose tissue (BAT), either via the brain or directly, which increases energy expenditure by combustion of fatty acids (FAs) into heat. The enzyme complex AMP-activated protein kinase (AMPK) is crucially involved in energy metabolism and is highly expressed in both brain and BAT, regulating thermogenesis. As a general rule, BAT activity and energy expenditure are increased either by suppression of AMPK activity in the brain, resulting in enhanced sympathetic outflow towards BAT, or by activation of AMPK in BAT. Targeting AMPK may thus hold therapeutic potential for the treatment of obesity and related disorders.

Effects of sulfonylureas on lipids in type 2 diabetes mellitus: a meta-analysis of randomized controlled trials

OBJECTIVE

Previous studies suggested that dyslipidemia was potentially associated with anti-diabetic medications of sulfonylureas (SUs). The results were, however, inconsistent. Therefore, we conducted a meta-analysis of randomized controlled trials (RCTs) to assess the effects of SUs on the level of lipids in patients with type 2 diabetes mellitus (T2DM).

METHODS

We searched PubMed, EMBASE, and CENTRAL databases for RCTs that addressed the effects of second- and/or third-generation SUs used in T2DM patients on lipids profiles with study duration of at least 12 weeks. Two reviewers independently screened literature, collected data, and assessed methodological quality of included studies. The meta-analysis was performed by using the RevMan5.1 software.

RESULTS

A total of 59 RCTs were included, of which 52 were included for final meta-analysis. The results suggested that SUs statistically increased the levels of FFA (SMD = 0.24, 95%CI 0.06 to 0.42) and TG (MD = 0.06, 95%CI 0.02 to 0.10), but decreased HDL-C (MD = -0.07, 95%CI -0.11 to -0.04) and LDL-C (MD = -0.11, 95%CI -0.17 to -0.04); but the SUs had no effect on TC (MD = 0.01, 95%CI -0.05 to 0.08), ApoA1 (MD = 0.01, 95%CI -0.03 to 0.04), and Apo B (MD = -0.01, 95%CI -0.05 to 0.03). When compared to metformin, SUs could increase TC and LDL-C; compared to glinides, SUs increased TC and lowered HDL-C; compared to thiazolidinediones, SUs reduced TC, LDL-C, HDL-C, and increase TG.

CONCLUSIONS

SUs have a small effect on lipids, although they may statistically increase the level of FFA and TG, and decrease LDL-C and HDL-C.

WITHDRAWN: Sulphonylurea monotherapy for patients with type 2 diabetes mellitus

The Cochrane Metabolic and Endocrine Disorders Group withdrew this review as of Issue 7, 2015 because of the involvement of one author (SS Lund) being employed in a pharmaceutical company. The authors of the review and the Cochrane Metabolic and Endocrine Disorders Group did not find that this was a breach of the rules of the Cochrane Collaboration at the time when it was published. However, after the publication of the review, the Cochrane Collaboration requested withdrawal of the review due to the employment of the author. A new protocol for a review to cover this topic will be published. This will have a new title and a markedly improved protocol fulfilling new and important developments and standards within the Cochrane Collaboration as well as an improved inclusion and search strategy making it necessary to embark on a completely new review project.

The editorial group responsible for this previously published document have withdrawn it from publication.

Polemics of pioglitazone: an appraisal in 2015

Pioglitazone is an inexpensive and effective oral drug for the treatment of Type 2 diabetes. It addresses insulin resistance, one of the core pathophysiological defects in Type 2 diabetes, at both the adipose tissue and skeletal muscle level. As a majority of Type 2 diabetics classically exhibit higher insulin resistance, pioglitazone may strike exactly at the Achilles heel in this core pathogenesis. However, with the emerging association of bladder cancer with pioglitazone, French and German regulators were the first to ban or restrict pioglitazone use in 2011. The Indian regulators also suspended pioglitazone, although this ban was revoked within a month. Recently, a 10-year longitudinal study commissioned by US FDA found no association between bladder cancer and pioglitazone. Nevertheless, this controversy created a huge outcry in the medical fraternity. This review article is an overview of the development of this topic and an attempt to provide perspective on this contemporary issue.

Comparison of glucose lowering effect of metformin and acarbose in type 2 diabetes mellitus: a meta-analysis

BACKGROUND

Metformin is the first-line oral hypoglycemic agent for type 2 diabetes mellitus recommended by international guidelines. However, little information exists comparing it with acarbose which is also commonly used in China. This study expanded knowledge by combining direct and indirect evidence to ascertain the glucose lowering effects of both drugs.

METHODS

PubMed (1980- December 2013) and China National Knowledge Infrastructure databases (1994-January 2014) were systematically searched for eligible randomized controlled trials from Chinese and English literatures. Meta-analysis was conducted to estimate the glucose lowering effects of metformin vs. acarbose, or either of them vs. common comparators (placebo or sulphonylureas), using random- and fixed-effect models. Bucher method with indirect treatment comparison calculator was applied to convert the summary estimates from the meta-analyses into weighted-mean-difference (WMD) and 95% confidence intervals (CIs) to represent the comparative efficacy between metformin and acarbose.

RESULTS

A total of 75 studies were included in the analysis. In direct comparison (8 trials), metformin reduced glycosylated hemoglobin (HbA1c) by 0.06% more than acarbose, with no significant difference (WMD,-0.06%; 95% CI, -0.32% to 0.20%). In indirect comparisons (67 trials), by using placebo and sulphonylureas as common comparators, metformin achieved significant HbA1c reduction than acarbose, by -0.38% (WMD,-0.38%, 95% CI, -0.736% to -0.024%) and -0.34% (WMD, -0.34%, 95% CI, -0.651% to -0.029%) respectively.

CONCLUSION

The glucose lowering effects of metformin monotherapy and acarbose monotherapy are the same by direct comparison, while metformin is a little better by indirect comparison. This implies that the effect of metformin is at least as good as acarbose's.

Sulfonylurea versus metformin monotherapy in patients with type 2 diabetes: a Cochrane systematic review and meta-analysis of randomized clinical trials and trial sequential analysis

BACKGROUND

Guidelines recommend metformin as the first-line oral treatment for type 2 diabetes. We conducted a systematic review to assess whether the use of second- and third-generation sulfonylurea agents is associated with benefits and harms in terms of patient-important outcomes compared with metformin.

METHODS

We searched several electronic databases and other sources for randomized clinical trials published to August 2011. We included trials that compared sulfonylurea versus metformin monotherapy among patients 18 years or older with type 2 diabetes and that had an intervention period of at least 24 weeks. We assessed risk of bias and extracted data related to interventions and outcomes. The risk of random errors was assessed by trial sequential analysis.

RESULTS

We included 14 trials (4560 participants). All trials were judged to be at high risk of bias. Data on patient-important outcomes were sparse. Compared with metformin, sulfonylurea did not significantly affect all-cause mortality (relative risk [RR] 0.98, 95% confidence interval [CI] 0.61 to 1.58) or cardiovascular mortality (RR 1.47, 95% CI 0.54 to 4.01). Sulfonylurea significantly decreased the risk of nonfatal macrovascular outcomes (RR 0.67, 95% CI 0.48 to 0.93). However, the definition of this outcome varied among trials, and trial sequential analysis showed that more trials are needed before reliable conclusions can be drawn. No differences between sulfonylurea and metformin were found for change in fasting blood glucose level or glycosylated hemoglobin concentration in the random-effects model. Sulfonylurea resulted in greater weight gain compared with metformin, a finding confirmed in the trial sequential analysis. Significantly more patients in the sulfonylurea arm than in the metformin arm had mild hypoglycemia (RR 2.95, 95% CI 2.13 to 4.07) and severe hypoglycemia (RR 5.64, 95% CI 1.22 to 26.00).

INTERPRETATION

Some evidence suggests that, compared with metformin, second- and third-generation sulfonylureas may not affect all-cause or cardiovascular mortality but may decrease the risk of nonfatal macrovascular outcomes among patients with type 2 diabetes. They may also increase the risk of hypoglycemia. In general, the available data were too few and inconsistent to provide firm evidence concerning patient-important outcomes in relation to the benefits and harms of sulfonylurea versus metformin monotherapy.

Randomized controlled trial of single-agent glimepiride and pioglitazone in Japanese patients with type 2 diabetes: A comparative study

Aims/Introduction:  To compare first‐line, single‐agent glimepiride and pioglitazone in Japanese patients with type 2 diabetes uncontrolled by diet and exercise with respect to glycemic control, safety and metabolic changes.

Materials and Methods:  Patients with previously untreated type 2 diabetes were enrolled in a multicenter, randomized, non‐blind, parallel‐group trial of glimepiride (0.5–6 mg/day) or pioglitazone (15–45 mg/day) for 6 months.

Results:  A total of 191 patients aged 30–75 years were randomized. Similar percentages of patients attained the primary end‐point, with glycated hemoglobin < 6.9% at month 6 with glimepiride and pioglitazone, respectively (61.2 vs 56.8%, P = 0.64). At month 6, the following significant (P < 0.05) intragroup changes in mean plasma lipid concentrations were noted as compared with baseline: total cholesterol decreased from 203.5 to 195.5 mg/dL and low‐density lipoprotein (LDL)‐cholesterol decreased from 124.5 to 116.3 mg/dL in the glimepiride group, whereas high‐density lipoprotein (HDL)‐cholesterol increased from 51.6 to 56.0 mg/dL and triglycerides decreased from 167.6 to 143.6 mg/dL in the pioglitazone group. The only symptomatic adverse events were mild‐to‐moderate in four patients receiving pioglitazone, and constipation in one patient receiving glimepiride. Similar numbers of patients experienced asymptomatic hypoglycemia (<60 mg/dL) in the glimepiride and pioglitazone groups (n = 7 and 5, respectively).

Conclusions:  There was no statistically significant difference between glimepiride and pioglitazone with respect to glycemic control, and both agents were well tolerated. Glimepiride significantly lowered total cholesterol and LDL‐cholesterol, whereas pioglitazone increased HDL‐cholesterol. This trial was registered with University Hospital Medical Information Network (UMIN), Japan, UMIN000004582. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00115.x, 2011)

Comparative efficacy of glimepiride and metformin in monotherapy of type 2 diabetes mellitus: meta-analysis of randomized controlled trials

BACKGROUND

Metformin treatment has been the most recommended monotherapy of type 2 diabetes mellitus (T2DM) for decades but is challenged by new antidiabetic drugs. This study conducted a meta-analysis of randomized controlled trials (RCT) comparing the efficacy of metformin and glimepiride in monotherapy of T2DM.

METHODS

A literature search for RCTs on glimepiride and metformin was conducted on the bibliographic databases, including PubMed, Cochrane Library and ScienceDirect, from their inceptions to 25 Mar 2013. All RCTs were selected according to pre-specified eligibility criteria. The quality of articles was assessed with the Cochrane's risk of bias tool. Statistical meta-analysis evaluated the overall effects and biochemical indices of T2DM. Sensitivity and subgroup analyses evaluated the robustness and explained the heterogeneity of the results. Begg and Egger's tests quantified possible publication biases. Results were represented as "standard mean difference or odds ratio [95% confidence internals] P value".

RESULTS

Fifteen RCTs with 1681 adult T2DM patients were included for meta-analysis. Metformin was not better than glimepiride in overall efficacy in controlling the levels of HbA1c, postprandial blood sugar (PPBS), fasting plasma insulin (FINS), systolic and diastolic blood pressures (SBP and DBP), and high density lipoprotein (HDL). Metformin was only more effective than glimepiride in controlling the levels of total cholesterol (TC, 0.33 [0.03, 0.63], P = 0.03), low-density lipoprotein (LDL, 0.35 [0.16, 0.53], P = 0.0002) and triglycerides (TG, 0.26 [0.05, 0.46], P = 0.01). Odds ratios of adverse events showed that glimepiride was more likely to induce hypoglycemia episodes and metformin was with a higher risk of gastrointestinal upset.

CONCLUSION

Metformin was not significantly better than glimepiride in glycemic control of T2DM, suggesting that glimepiride would be a good choice second to metformin in the monotherapy of T2DM.

Cardiovascular safety of sulfonylureas: a meta-analysis of randomized clinical trials

AIM

Cardiovascular safety of sulfonylurea has been questioned by some authors. This article aims at collecting all available data on this issue from randomized trials.

METHODS

A meta-analysis was performed including all trials with a duration of at least 6 months, comparing a sulfonylurea with a non-sulfonylurea agent in type 2 diabetes. Major cardiovascular events (MACE) and mortality were retrieved and combined to calculate Mantel-Haenzel odds ratio (MH-OR).

RESULTS

Of the 115 selected trials, 62 reported information on MACE, and 30 reported at least one event. MH-OR for sulfonylurea was 1.08 [0.86-1.36], p = 0.52 (1.85 [1.20-2.87], p = 0.005, in the five trials vs. DPP4 inhibitors, no significant differences vs. other comparators). The MH-OR for myocardial infarction and stroke was 0.88 [0.75-1.04], p = 0.13 and 1.28 [1.03-1.60], p = 0.026, respectively. Mortality was significantly increased with sulfonylureas (MH-OR: 1.22 [1.01-1.49], p = 0.047).

CONCLUSIONS

In type 2 diabetes, the use of sulfonylureas is associated with increased mortality and a higher risk of stroke, whereas the overall incidence of MACE appears to be unaffected. Significant differences in cardiovascular risk could be present in direct comparisons with specific classes of glucose-lowering agents, such as DPP4 inhibitors, but this hypothesis needs to be confirmed in long-term cardiovascular outcomes trials. The results of this meta-analysis need to be interpreted with caution, mainly because of limitations in trial quality and under-reporting of information on cardiovascular events and mortality. However, the cardiovascular safety of sulfonylureas cannot be considered established unless it is evaluated in long-term cardiovascular outcomes trials.

Methodology for quantifying fasting glucose homeostasis in type 2 diabetes: observed variability and lability

BACKGROUND

Increased glycemic variability is associated with an increase risk of adverse clinical outcomes in diabetes. Central to the understanding of diabetes is glucose homeostasis. "Good" homeostasis is equated to low glycemic variability, and "poor" homeostasis is linked to greater glycemic variability. We have, therefore, developed a method with the aim to objectively quantify the domain of glucose-insulin homeostasis. We have termed this method as Observed Variability And Lability (OVAL).

METHOD

Blood samples for the measurement of glucose and insulin concentrations were acquired every 2 min for 120 min from 12 patients with type 2 diabetes mellitus [T2DM; median (range) age 35 (25-47) years and duration of diabetes 7 (2-9) years receiving oral hypoglycemic treatment] and 27 controls [aged 38(30-53) years] with an equal split of genders and equal distribution of body mass indexes. The insulin-glucose time variant data form the boundaries of OVAL, defined as the ellipse enclosing the 95% confidence intervals of the insulin and glucose concentrations plotted on an x-y scatter graph and normalized to ensure equal weighting of insulin and glucose.

RESULTS

Less precise OVAL homeostasis was observed in subjects with T2DM, by a factor of 4, in comparison with controls [OVAL, T2DM 7.8(3.8) versus controls 1.9(1.0); p = .0003]. The assessment remained statistically robust (p < .001) with increased sampling intervals up to 8 min.

CONCLUSION

The OVAL model is a robust method for measuring glucose-insulin homeostasis in controls and T2DM subjects (available online at http://www.oval-calc.co.uk). Deranged glucose-insulin homeostasis is the hallmark of diabetes and OVAL has the capacity to quantify in the fasting state.

Sulphonylurea monotherapy for patients with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a growing health problem worldwide. Whether sulphonylureas show better, equal or worse therapeutic effects in comparison with other antidiabetic interventions for patients with T2DM remains controversial.

OBJECTIVES

To assess the effects of sulphonylurea monotherapy versus placebo, no intervention or other antidiabetic interventions for patients with T2DM.

SEARCH METHODS

We searched publications in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, LILACS and CINAHL (all until August 2011) to obtain trials fulfilling the inclusion criteria for our review.

SELECTION CRITERIA

We included clinical trials that randomised patients 18 years old or more with T2DM to sulphonylurea monotherapy with a duration of 24 weeks or more.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias. The primary outcomes were all-cause and cardiovascular mortality. Secondary outcomes were other patient-important outcomes and metabolic variables. Where possible, we used risk ratios (RR) with 95% confidence intervals (95% CI) to analyse the treatment effect of dichotomous outcomes. We used mean differences with 95% CI to analyse the treatment effect of continuous outcomes. We evaluated the risk of bias. We conducted trial sequential analyses to assess whether firm evidence could be established for a 10% relative risk reduction (RRR) between intervention groups.

MAIN RESULTS

We included 72 randomised controlled trials (RCTs) with 22,589 participants; 9707 participants randomised to sulphonylureas versus 12,805 participants randomised to control interventions. The duration of the interventions varied from 24 weeks to 10.7 years. We judged none of the included trials as low risk of bias for all bias domains. Patient-important outcomes were seldom reported.First-generation sulphonylureas (FGS) versus placebo or insulin did not show statistical significance for all-cause mortality (versus placebo: RR 1.46, 95% CI 0.87 to 2.45; P = 0.15; 2 trials; 553 participants; high risk of bias (HRB); versus insulin: RR 1.18, 95% CI 0.88 to 1.59; P = 0.26; 2 trials; 1944 participants; HRB). FGS versus placebo showed statistical significance for cardiovascular mortality in favour of placebo (RR 2.63, 95% CI 1.32 to 5.22; P = 0.006; 2 trials; 553 participants; HRB). FGS versus insulin did not show statistical significance for cardiovascular mortality (RR 1.36, 95% CI 0.68 to 2.71; P = 0.39; 2 trials; 1944 participants; HRB). FGS versus alpha-glucosidase inhibitors showed statistical significance in favour of FGS for adverse events (RR 0.63, 95% CI 0.52 to 0.76; P = 0.01; 2 trials; 246 participants; HRB) and for drop-outs due to adverse events (RR 0.28, 95% CI 0.12 to 0.67; P = 0.004; 2 trials; 246 participants; HRB).Second-generation sulphonylureas (SGS) versus metformin (RR 0.98, 95% CI 0.61 to 1.58; P = 0.68; 6 trials; 3528 participants; HRB), thiazolidinediones (RR 0.92, 95% CI 0.60 to 1.41; P = 0.70; 7 trials; 4955 participants; HRB), insulin (RR 0.96, 95% CI 0.79 to 1.18; P = 0.72; 4 trials; 1642 participants; HRB), meglitinides (RR 1.44, 95% CI 0.47 to 4.42; P = 0.52; 7 trials; 2038 participants; HRB), or incretin-based interventions (RR 1.39, 95% CI 0.52 to 3.68; P = 0.51; 2 trials; 1503 participants; HRB) showed no statistically significant effects regarding all-cause mortality in a random-effects model. SGS versus metformin (RR 1.47; 95% CI 0.54 to 4.01; P = 0.45; 6 trials; 3528 participants; HRB), thiazolidinediones (RR 1.30, 95% CI 0.55 to 3.07; P = 0.55; 7 trials; 4955 participants; HRB), insulin (RR 0.96, 95% CI 0.73 to 1.28; P = 0.80; 4 trials; 1642 participants; HRB) or meglitinide (RR 0.97, 95% CI 0.27 to 3.53; P = 0.97; 7 trials, 2038 participants, HRB) showed no statistically significant effects regarding cardiovascular mortality. Mortality data for the SGS versus placebo were sparse. SGS versus thiazolidinediones and meglitinides did not show statistically significant differences for a composite of non-fatal macrovascular outcomes. SGS versus metformin showed statistical significance in favour of SGS for a composite of non-fatal macrovascular outcomes (RR 0.67, 95% CI 0.48 to 0.93; P = 0.02; 3018 participants; 3 trials; HRB). The definition of non-fatal macrovascular outcomes varied among the trials. SGS versus metformin, thiazolidinediones and meglitinides showed no statistical significance for non-fatal myocardial infarction. No meta-analyses could be performed for microvascular outcomes. SGS versus placebo, metformin, thiazolidinediones, alpha-glucosidase inhibitors or meglitinides showed no statistical significance for adverse events. SGS versus alpha-glucosidase inhibitors showed statistical significance in favour of SGS for drop-outs due to adverse events (RR 0.48, 95% CI 0.24 to 0.96; P = 0.04; 9 trials; 870 participants; HRB). SGS versus meglitinides showed no statistical significance for the risk of severe hypoglycaemia. SGS versus metformin and thiazolidinediones showed statistical significance in favour of metformin (RR 5.64, 95% CI 1.22 to 26.00; P = 0.03; 4 trials; 3637 participants; HRB) and thiazolidinediones (RR 6.11, 95% CI 1.57 to 23.79; P = 0.009; 6 trials; 5660 participants; HRB) for severe hypoglycaemia.Third-generation sulphonylureas (TGS) could not be included in any meta-analysis of all-cause mortality, cardiovascular mortality or non-fatal macro- or microvascular outcomes. TGS versus thiazolidinediones showed statistical significance regarding adverse events in favour of TGS (RR 0.88, 95% CI 0.78 to 0.99; P = 0.03; 3 trials; 510 participants; HRB). TGS versus thiazolidinediones did not show any statistical significance for drop-outs due to adverse events. TGS versus other comparators could not be performed due to lack of data.For the comparison of SGS versus FGS no meta-analyses of all-cause mortality, cardiovascular mortality, non-fatal macro- or microvascular outcomes, or adverse events could be performed.Health-related quality of life and costs of intervention could not be meta-analysed due to lack of data.In trial sequential analysis, none of the analyses of mortality outcomes, vascular outcomes or severe hypoglycaemia met the criteria for firm evidence of a RRR of 10% between interventions.

AUTHORS' CONCLUSIONS

There is insufficient evidence from RCTs to support the decision as to whether to initiate sulphonylurea monotherapy. Data on patient-important outcomes are lacking. Therefore, large-scale and long-term randomised clinical trials with low risk of bias, focusing on patient-important outcomes are required.

Safety, tolerability, and efficacy of metformin extended-release oral antidiabetic therapy in patients with type 2 diabetes: an observational trial in Asia

BACKGROUND

The aim of the present prospective observational study was to assess the tolerability and antihyperglycemic efficacy of metformin extended-release (MXR) in the routine treatment of patients with type 2 diabetes mellitus (T2DM) from six Asian countries.

METHODS

Data from 3556 patients treated with once-daily MXR for 12 weeks, or until discontinuation, were analyzed.

RESULTS

Treatment with MXR was well tolerated, with 97.4% of patients completing 12 weeks of treatment. Only 3.3% of patients experienced one or more gastrointestinal (GI) side-effects and only 0.7% of patients discontinued for this reason (primary endpoint). The incidence of GI side-effects and related discontinuations appeared to be considerably lower during short-term MXR therapy than during previous treatment (mean 2.71 years' duration), most commonly with immediate-release metformin. A 12-week course of MXR therapy also reduced HbA1c and fasting glucose levels from baseline.

CONCLUSIONS

The present study provides new insights into the incidence of GI side-effects with MXR in Asian patients with T2DM and on the tolerability of MXR in non-Caucasian populations. Specifically, these data indicate that once-daily MXR not only improves measures of glycemic control in Asian patients with T2DM, but also has a favorable GI tolerability profile that may help promote enhanced adherence to oral antidiabetic therapy.

Pioglitazone prevents hyperglycemia induced decrease of AdipoR1 and AdipoR2 in coronary arteries and coronary VSMCs

BACKGROUND

Adiponectin receptors play an important role in inflammatory diseases like diabetes and atherosclerosis. Former studies revealed that the regulation of adiponectin receptors expression differs in the receptor responses to pioglitazone. However, expression of AdipoRs has not been investigated in the coronary arteries or the coronary vascular smooth muscle cells (VSMCs). In the present study we investigated the effect of pioglitazone on the adiponectin receptors both in vitro and in vivo.

METHODS

Male Sprague-Dawley rats were randomly divided in three groups. One of them fed with regular chow (the Control group) and two of them fed with high-fat diet and then received low-dose Streptozotocin once by intraperitoneal injection (the DM groups). Rats in one of the DM groups were further treated with pioglitazone (the PIO group). Blood pressure, serum adiponectin, fasting blood glucose, fasting serum insulin, cholesterol, triglyceride, AdipoR1 and AdipoR2 expression, and TNF-α expression in coronary arteries of these groups were investigated. For the in vitro study, the rat coronary VSMCs maintained under defined in vitro conditions were treated with either PIO or the PIO+ GW9662 (PPAR-γ antagonist), and then stimulated with high glucose. AdipoR1 and AdipoR2 expression, TNF-α expression and PPAR-γ expression were investigated.

RESULTS

Compared to the DM group, treatment with PIO in vivo significantly attenuated cholesterol level, triglyceride level, fasting serum insulin and TNF-α overexpression (p<0.05). PIO also increased AdipoR1 and AdipoR2 expression in coronary arteries, which were reduced notably in the DM group (p<0.05). Consistently, in the study with rat coronary VSMCs, PIO prominently downregulated TNF-α expression and induced PPAR-γ expression, as well as prevented hyperglycemia induced decrease of AdipoR1 and AdipoR2 expression (p<0.05). And pretreatment of PIO+GW9662 did not manifest the prevention effect.

CONCLUSION

In this study, we showed that treatment with PIO could ameliorate coronary insulin resistant and upregulate the expression of AdipoR1/R2. PIO showed an anti-atherogenic property via the activation of PPAR-γ, suppression of TNF-α overexpression in coronary and coronary VSMCs.

PPAR-γ as a therapeutic target in cardiovascular disease: evidence and uncertainty

Peroxisome proliferator-activated receptor γ (PPAR-γ) is a key regulator of fatty acid metabolism, promoting its storage in adipose tissue and reducing circulating concentrations of free fatty acids. Activation of PPAR-γ has favorable effects on measures of adipocyte function, insulin sensitivity, lipoprotein metabolism, and vascular structure and function. Despite these effects, clinical trials of thiazolidinedione PPAR-γ activators have not provided conclusive evidence that they reduce cardiovascular morbidity and mortality. The apparent disparity between effects on laboratory measurements and clinical outcomes may be related to limitations of clinical trials, adverse effects of PPAR-γ activation, or off-target effects of thiazolidinedione agents. This review addresses these issues from a clinician's perspective and highlights several ongoing clinical trials that may help to clarify the therapeutic role of PPAR-γ activators in cardiovascular disease.

Comparison of the efficacy of glimepiride, metformin, and rosiglitazone monotherapy in korean drug-naïve type 2 diabetic patients: the practical evidence of antidiabetic monotherapy study

BACKGROUND

Although many anti-diabetic drugs have been used to control hyperglycemia for decades, the efficacy of commonly-used oral glucose-lowering agents in Korean type 2 diabetic patients has yet to be clearly demonstrated.

METHODS

We evaluated the efficacy of glimepiride, metformin, and rosiglitazone as initial treatment for drug-naïve type 2 diabetes mellitus patients in a 48-week, double-blind, randomized controlled study that included 349 Korean patients. Our primary goal was to determine the change in HbA1c levels from baseline to end point. Our secondary goal was to evaluate changes in fasting plasma glucose (FPG) levels, body weight, frequency of adverse events, and the proportion of participants achieving target HbA1c levels.

RESULTS

HbA1c levels decreased from 7.8% to 6.9% in the glimepiride group (P<0.001), from 7.9% to 7.0% in the metformin group (P<0.001), and from 7.8% to 7.0% (P<0.001) in the rosiglitazone group. Glimepiride and rosiglitazone significantly increased body weight and metformin reduced body weight during the study period. Symptomatic hypoglycemia was more frequent in the glimepiride group and diarrhea was more frequent in the metformin group.

CONCLUSION

The efficacy of glimepiride, metformin, and rosiglitazone as antidiabetic monotherapies in drug-naïve Korean type 2 diabetic patients was similar in the three groups, with no statistical difference. This study is the first randomized controlled trial to evaluate the efficacy of commonly-used oral hypoglycemic agents in Korean type 2 diabetic patients. An additional subgroup analysis is recommended to obtain more detailed information.

Therapies for type 2 diabetes: lowering HbA1c and associated cardiovascular risk factors

OBJECTIVES

To summarize data supporting the effects of antidiabetes agents on glucose control and cardiovascular risk factors in patients with type 2 diabetes.

METHODS

Studies reporting on the effects of antidiabetes agents on glycemic control, body weight, lipid levels, and blood pressure parameters are reviewed and summarized for the purpose of selecting optimal therapeutic regimens for patients with type 2 diabetes.

RESULTS

National guidelines recommend the aggressive management of cardiovascular risk factors in patients with type 2 diabetes, including weight loss and achieving lipid and blood pressure treatment goals. All antidiabetes pharmacotherapies lower glucose; however, effects on cardiovascular risk factors vary greatly among agents. While thiazolidinediones, sulfonylureas, and insulin are associated with weight gain, dipeptidyl peptidase-4 inhibitors are considered weight neutral and metformin can be weight neutral or associated with a small weight loss. Glucagon-like peptide-1 receptor agonists and amylinomimetics (e.g. pramlintide) result in weight loss. Additionally, metformin, thiazolidinediones, insulin, and glucagon-like peptide-1 receptor agonists have demonstrated beneficial effects on lipid and blood pressure parameters.

CONCLUSION

Management of the cardiovascular risk factors experienced by patients with type 2 diabetes requires a multidisciplinary approach with implementation of treatment strategies to achieve not only glycemic goals but to improve and/or correct the underlying cardiovascular risk factors.

Pharmacogenetics of Anti-Diabetes Drugs

A variety of treatment modalities exist for individuals with type 2 diabetes mellitus (T2D). In addition to dietary and physical activity interventions, T2D is also treated pharmacologically with nine major classes of approved drugs. These medications include insulin and its analogues, sulfonylureas, biguanides, thiazolidinediones (TZDs), meglitinides, α-glucosidase inhibitors, amylin analogues, incretin hormone mimetics, and dipeptidyl peptidase 4 (DPP4) inhibitors. Pharmacological treatment strategies for T2D are typically based on efficacy, yet favorable responses to such therapeutics are oftentimes variable and difficult to predict. Characterization of drug response is expected to substantially enhance our ability to provide patients with the most effective treatment strategy given their individual backgrounds, yet pharmacogenetic study of diabetes medications is still in its infancy. To date, major pharmacogenetic studies have focused on response to sulfonylureas, biguanides, and TZDs. Here, we provide a comprehensive review of pharmacogenetics investigations of these specific anti-diabetes medications. We focus not only on the results of these studies, but also on how experimental design, study sample issues, and definition of 'response' can significantly impact our interpretation of findings. Understanding the pharmacogenetics of anti-diabetes medications will provide critical baseline information for the development and implementation of genetic screening into therapeutic decision making, and lay the foundation for "individualized medicine" for patients with T2D.

Effects of thiazolidinediones and sulfonylureas in patients with diabetes

In the current literature there are different opinions about the use of thiazolidinediones or sulfonylureas. Some authors have reported that thiazolidinediones increase total body glucose disposal and reduce hepatic glucose production, reducing both peripheral and hepatic insulin resistance (or enhances both peripheral and insulin sensitivity). They consider thiazolidinediones a better drug compared to sulfonylureas because they do not induce hypoglycemia and they provide a protection for the pancreatic beta-cell. On the other side, some authors have reported that the improved glycemic control obtained with thiazolidinedione use is associated with an increase in body weight and a worsening of lipid profile, and they also warn providers to consider the potential for serious adverse cardiovascular effects of the treatment with rosiglitazone for type 2 diabetes mellitus, negating some of the benefits of the improved metabolic control. They have also reported that sulfonylureas are safer compared to thiazolidinediones because they give a better and faster improvement of glycated hemoglobin without giving the adverse effects reported with the use of thiazolidinediones. Considering the emerging discrepancies from these studies we decided to undertake a thorough literature search on Medline and Embase to evaluate the effects of thiazolidinediones and sulfonylureas in people with diabetes. In particular, this review examines the effects and the rationale and practicalities for the use of sulfonylureas or thiazolidinediones, alone and in combination therapy with other antidiabetes drugs, to treat type 2 diabetes mellitus considering, as primary end points, glycated hemoglobin, fasting plasma glucose, fasting plasma insulin, homeostasis model assessment indices, body weight, body mass index, blood pressure, and, when available, data on lipid profile. We also evaluated the effects of these two drugs on beta-cell function, insulin resistance, and inflammatory markers, also recording the frequency of adverse events such as edema and heart failure.

Concomitant therapy with pioglitazone and insulin for the treatment of type 2 diabetes

To prevent hyperinsulinemia, which may cause atherosclerosis, thiazolidinediones (TZDs), also known as insulin sensitizers, are often added to the therapeutic regimen of patients with type 2 diabetes who are receiving insulin. The combination of insulin with pioglitazone, a TZD, reduces glycoated hemoglobin (HbA(1c)) by 0.6%-2.1%. The higher the HbA(1c) baseline the larger the therapeutic reduction of HbA(1c). This combination therapy has been shown to be beneficial even in lean Japanese patients with diabetes. It should be noted that such combination therapy is much more useful when the main clinical aim is lowering not postprandial, but fasting and nocturnal glycemia. The glycemic-lowering effects of pioglitazone alone occur slowly, whereas the addition of insulin to pioglitazone often shows a dramatic glucose-lowering effect. Thus, such combination therapy increases the possibility of frequent hypoglycemia within 1 to 2 months of combining the drugs. Severe hypoglycemia in patients using this therapy is rare. Patients treated with combination therapy who show a predominant reduction of glycemia often have severe edema; in 10%-20% of patients, combination therapy leads to drug-related congestive heart failure (CHF). However, this phenomenon is usually weakened if low doses of pioglitazone which are added to insulin therapy (ie, 15 mg/day or even 7.5 mg/day for women). It is well known that pioglitazone has an anti-atherosclerotic effect, although it is unclear if hyperinsulinemia induces atherogenic changes, either directly or indirectly, by the promotion of obesity. Until now, we have not confirmed whether the anti-atherosclerotic effects of pioglitazone exceed the supposed disadvantageous action of insulin when used in combination therapy. The addition of pioglitazone tends to reduce daily insulin dosages, but study findings have not been consistent. Improvement of lipid profiles has also been weak with this combination therapy. Long-term trials are needed before any conclusions can be reached concerning atherogenic effects of treatment for type 2 diabetes. Combination therapy of even small doses of pioglitazone with insulin should be primarily used for patients who achieve insufficient reduction in glycemia with insulin monotherapy.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators.

SELECTION CRITERIA

Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy.

DATA COLLECTION AND ANALYSIS

The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data.

MAIN RESULTS

Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies.

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.

Relationship of baseline HbA1c and efficacy of current glucose-lowering therapies: a meta-analysis of randomized clinical trials

AIMS

Baseline glycated haemoglobin (HbA(1c)) concentrations vary between clinical trials of glucose-lowering agents and this may affect interpretation of clinical efficacy. The objective of this study is to quantify the relationship between baseline HbA(1c) and reduction of HbA(1c) in clinical trials.

METHODS

PubMed literature searches from 1991 to 2007. Randomized controlled studies with placebo-controlled or comparator arms [> or = 9 patients in the intent-to-treat (ITT) population] ranging in duration from 23 to 52 weeks, in which baseline and change in glycated haemoglobin (HbA(1c)) were reported. The relationship between baseline HbA(1c) and change in HbA(1c) was analysed by a weighted least-squared regression model accounting for ITT population and variance of HbA(1c) change. Fourteen per cent of independently abstracted studies met the selection criteria.

RESULTS

Meta-analysis from 59 clinical trials (8479 patients) produced weighted R(2) of 0.35 (P < 0.0001) for the association of baseline HbA(1c) and absolute change in HbA(1c). Subanalysis of eight metformin clinical trials demonstrated a stronger association [weighted R(2) of 0.67 (P = 0.0130)]. Exclusion of metformin clinical trials from the overall meta-analysis (n = 51) yielded a weighted R(2) of 0.31 (P < 0.0001). Subanalyses of clinical trials of glucose-lowering therapies predominantly targeting fasting (n = 37) or postprandial (n = 22) blood glucose produced weighted R(2) values of 0.27 (P < 0.001) and 0.42 (P < 0.005), respectively.

CONCLUSIONS

These data demonstrate a positive relationship between baseline HbA(1c) and the magnitude of HbA(1c) change across 10 categories of glucose-lowering therapies, irrespective of class or mode of action. These observations should be considered when assessing clinical efficacy of diabetes therapies derived from clinical trials.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators.

SELECTION CRITERIA

Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy.

DATA COLLECTION AND ANALYSIS

The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data.

MAIN RESULTS

Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies.

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.

The impact of weight gain on motivation, compliance, and metabolic control in patients with type 2 diabetes mellitus

Patients with type 2 diabetes, approximately 85% of whom are overweight or obese, often have an increased incidence of cardiovascular disease (CVD) risk factors such as hypertension and dyslipidemia. Both type 2 diabetes and obesity are independent risk factors for CVD. Unfortunately, many therapies aimed at maintaining and improving glucose control are associated with weight gain. Among the older antidiabetes agents, most, including the insulin secretagogues and sensitizers, can lead to weight gain, except for metformin, which is weight-neutral. Among the newer agents, the dipeptidyl peptidase-4 inhibitors generally are weight-neutral in addition to lowering glucose, while the glucagon-like peptide-1 receptor agonists lead to weight reduction. Patients with type 2 diabetes are at an increased risk for both diabetes- and CV-related outcomes, and weight reduction is an important component of diabetes management. Weight gain in patients with type 2 diabetes can contribute to patient frustration and may negatively impact their compliance to therapeutic regimens. The selection of antidiabetes agents that not only improve glucose control but reduce or have a neutral effect on weight with beneficial effects on lipids are ideal options for managing patients with type 2 diabetes.

Factors associated with results and conclusions of trials of thiazolidinediones

Background

When a sponsor funds a study of two competing drugs in a head-to-head comparison, the results and conclusions are likely to favor the sponsor’s drug. Thiazolidinediones, oral medications used for the treatment of type 2 diabetes, are one of the most costly choices of oral anti-diabetic medications, yet they do not demonstrate clinically relevant differences in achieving lower glycosylated hemoglobin levels compared to other oral antidiabetic drugs. Our aim is to examine associations between research funding source, study design characteristics aimed at reducing bias, and other factors with the results and conclusions of randomized controlled trials (RCTs) of thiazolidinediones compared to other oral hypoglycemic agents.

Methods and Findings

This is a cross-sectional study of 61 published RCTs comparing a thiazolidinedione (glitazone) to another anti-diabetic drug or placebo for treatment of type 2 diabetes. Data on study design characteristics, funding source, author’s financial ties, results for primary outcomes, and author conclusions were extracted. Univariate logistic regression identified associations between independent variables and results and conclusions that favored the glitazone. Of the RCTs, 59% (36/61) were funded by industry, 39% (24/61) did not disclose any funding. Common study design weaknesses included inadequate blinding and lack of concealment of allocation. Trials that reported favorable glycemic control results for the glitazone were more likely to have adequate blinding (OR (95% CI)  = 5.42 (1.46, 21.19), p = 0.008) and have a corresponding author with financial ties to the glitazone manufacturer (OR (95% CI)  = 4.12 (1.05, 19.53); p = 0.04). Trials with conclusions favoring the glitazone were less likely to be funded by a comparator drug company than a glitazone company (OR (95% CI)  = 0.026 (0, 0.40), p = 0.003) and less likely to be published in journals with higher impact factors (OR (95% CI)  = 0.79 (0.62, 0.97), p = 0.011). One limitation of our study is that we categorized studies as funded by industry based on each article’s disclosure which could underestimate the number of industry sponsored studies and personal ties of investigators. Additionally, our study did not include any head-to-head comparisons of one glitazone to another.

Conclusions

Published RCT comparisons of glitazones with other anti-diabetic drugs or placebo are predominantly industry supported and this support, as well as the financial ties of study authors, appears to be associated with favorable findings.

Free fatty acid kinetics during long-term treatment with pioglitazone added to sulfonylurea or metformin in Type 2 diabetes

BACKGROUND

Free fatty acids (FFAs) are linked to impaired insulin action, but their role in mediating long-term insulin sensitization during diabetes treatment is unclear.

OBJECTIVES

To examine the effect of pioglitazone addition to existing therapy on FFA dynamics and insulin action.

DESIGN

Two 2-year, randomized, parallel-group, double-blind, double-dummy, clinical trials.

SETTING

One hundred and seventy-one centres in Europe, Australia and Canada.

SUBJECTS

Male and female patients with Type 2 diabetes inadequately managed with metformin or sulfonylurea.

INTERVENTIONS

Patients were randomized to pioglitazone (15-45 mg day(-1); n=319) or metformin (850-2550 mg day(-1); n=320) as add-on therapy to gliclazide or pioglitazone (n=317) versus gliclazide (80-320 mg day(-1); n=313) as add-on therapy to metformin.

OUTCOME MEASURE

Plasma FFA profiles during oral glucose tolerance tests in selected centres before and during treatment (n=588).

RESULTS

At Week 104, pioglitazone treatment decreased fasting FFAs by 0.08 mmol L(-1) when added to sulfonylurea and by 0.11 mmol L(-1) when added to metformin versus the respective sulfonylurea + metformin groups (0.03 mmol L(-1), P=0.05 and 0.04 mmol L(-1), P<0.05), and this was accompanied by significant improvements in fasting adipose tissue insulin sensitivity. Changes in postchallenge FFAs were similar between groups and not related to changes in liver transaminases, insulin action and secretion. However, the sensitivity of FFA to insulin was affected by treatment (P<0.001) and visit (P<0.05). Insulin sensitivity of FFA rose when pioglitazone was added to sulfonylurea (P<0.05), but decreased for gliclazide + metformin (P<0.05).

CONCLUSION

Long-term improvements in adipose tissue insulin sensitivity and reduction in fasting FFAs with pioglitazone may help to reduce lipotoxicity in Type 2 diabetes.

Pioglitazone and cardiovascular risk. A comprehensive meta-analysis of randomized clinical trials

AIM

The aim of this meta-analysis of randomized clinical trials (RCT) was to assess whether pioglitazone is also associated with increased cardiovascular risk, as recently reported for rosiglitazone.

METHODS

RCT of pioglitazone were retrieved from Medline (any date up to 31 August 2007; English language only). Unpublished RCT were identified through http://www.clinicaltrials.gov or http://www.fda.gov websites, and results on cardiovascular outcomes were retrieved from investigators and/or sponsors, whenever possible. RCT were included in meta-analysis if pioglitazone was compared with other treatments (placebo, active comparators or no treatment) for at least 4 weeks. Ninety-four trials, 10 of which were unpublished, were retrieved; those included in the analysis, which excluded PROspective PioglitAzone Clinical Trial In MacroVascular Events (PROACTIVE), enrolled 11 268 and 9912 patients in the pioglitazone and comparator groups respectively. Data for analysis, extracted independently by two observers, included all-cause and cardiovascular mortality and incidence of non-fatal coronary events and heart failure. Proportions of outcome measures across treatment groups were compared by odds ratios (ORs) and 95% confidence interval.

RESULTS

Pioglitazone was associated with reduced all-cause mortality [OR 0.30 (0.14-0.63); p < 0.05], with no relevant effect on non-fatal coronary events. The observed increase in incidence of non-fatal heart failure was not statistically significant [OR 1.38 (0.90-2.12)].

CONCLUSION

The use of pioglitazone does not appear to be harmful in terms of cardiovascular events and all-cause deaths.

Effects of metformin on peripheral insulin sensitivity and intracellular lipid contents in muscle and liver of overweight Japanese subjects

AIM

Recent studies suggest that insulin resistance is associated with increased intrahepatic lipid (IHL) and intramyocellular lipid (IMCL) contents. While metformin improves insulin resistance mainly in liver, its effects on IHL and IMCL have not been clarified yet. The aim of this study was to investigate the effects of low-dose metformin (750 mg/day) on peripheral insulin sensitivity, IHL and IMCL.

METHODS

Before and 3 months after low-dose metformin therapy, eight overweight/obese Japanese subjects [body mass index (BMI) >25 kg/m2] were studied with blood sampling, measurement of IHL and IMCL by 1H magnetic resonance spectroscopy and glucose infusion rate (GIR) during euglycaemic-hyperinsulinaemic clamp as an index of peripheral insulin sensitivity.

RESULTS

A 3-month low-dose metformin therapy did not alter body weight, total body fat, fat distribution or physical activity level but increased GIR by 31% (from 6.24 +/- 0.86 to 7.82 +/- 0.82 mg/kg/min, p < 0.01). Although metformin treatment did not alter IMCL (from 4.1 +/- 1.0 to 4.2 +/- 0.9, not significant), it decreased IHL by 21% (from 15.9 +/- 2.8 to 11.8 +/- 2.2%, p < 0.05).

CONCLUSIONS

A 3-month low-dose metformin treatment improved peripheral insulin sensitivity and reduced IHL, without significantly changing BMI, adiposity or IMCL.

1,5-anhydroglucitol (GlycoMark) as a marker of short-term glycemic control and glycemic excursions

1,5-anhydroglucitol (1,5-AG) is a validated marker of short-term glycemic control. It is a metabolically inert polyol that competes with glucose for reabsorption in the kidneys. Otherwise stable levels of 1,5-AG are rapidly depleted as blood glucose levels exceed the renal threshold for glucosuria. 1,5-AG more accurately predicts rapid changes in glycemia than hemoglobin A1C (A1C) or fructosamine. It is also more tightly associated with glucose fluctuations and postprandial glucose. Thus, 1,5-AG may offer complementary information to A1C. This review will summarize the limitations of current methods of assessing glycemic control, assess the data to support 1,5-AG as a glycemic marker and highlight the scenarios by which 1,5-AG may fill the gap in assessing glycemic control.

Comparison of the effects of pioglitazone and voglibose on circulating total and high-molecular-weight adiponectin, and on two fibrinolysis inhibitors, in patients with Type 2 diabetes

BACKGROUND

To investigate short-term effects of pioglitazone and voglibose on serum concentrations of both total and high-molecular-weight (HMW) adiponectin measured with a novel sandwich enzyme-linked immunosorbent assay (ELISA) ,and on plasma fibrinolysis indicators, in Type 2 diabetic patients with inadequate glycaemic control on sulphonylureas.

METHODS

Thirty-four diabetic patients were randomized to receive pioglitazone or voglibose treatment for 12 weeks, after which serum HMW adiponectin was measured. Plasma plasminogen activator inhibitor (PAI) 1 and thrombin-activatable fibrinolysis inhibitor (TAFI), a recently identified inhibitor of fibrinolysis, were measured as fibrinolysis inhibitors.

RESULTS

At baseline, serum HMW adiponectin correlated negatively with plasma TAFI in all patients with Type 2 diabetes (r = -0.367, P = 0.0423). Both groups showed similar improvements in glycaemic control. Serum total and HMW adiponectin increased in patients treated with pioglitazone, but did not change in patients treated with voglibose. The HMW : total adiponectin ratio increased significantly after treatment with pioglitazone (P = 0.0004). The change in HbA(1c) correlated negatively with changes in serum HMW adiponectin in patients treated with pioglitazone (r = -0.694, P = 0.0034). Plasma PAI-1 and TAFI did not change with pioglitazone treatment.

CONCLUSION

Increased serum HMW adiponectin may contribute to the improvement in glycaemic control after pioglitazone treatment. Plasma PAI-1 and TAFI were unchanged by either drug.

The effects of pioglitazone on cerebrovascular resistance in patients with type 2 diabetes mellitus

Atherosclerosis is one of the major causes of morbidity and mortality in patients with type 2 diabetes mellitus. Pioglitazone has been reported to have antiatherogenic effects. The aim of this study was to investigate whether pioglitazone affects pulsatility index (PI) of the cerebral arteries and the carotid intima-media thickness in type 2 diabetic patients. A total of 40 type 2 diabetic patients were included in this study. They were divided into 2 groups: the pioglitazone-treated group (pioglitazone 15 mg/d with gliclazide 80-320 mg/d for 12 weeks) and the gliclazide-treated group (gliclazide 80-320 mg/d for 12 weeks). Transcranial Doppler ultrasonography was performed for each cerebral artery, and PI was calculated as (systolic velocity-diastolic velocity)/mean velocity. The pioglitazone treatment significantly increased high-density lipoprotein cholesterol and decreased triglyceride levels and insulin resistance. This study revealed that the change in mean intima-media thickness was not significant in both groups, but the change in PI was significantly decreased with pioglitazone compared to gliclazide. In conclusion, pioglitazone decreased PI and improved cerebrovascular resistance in type 2 diabetic patients.

Metformin and body weight

Most patients with type 2 diabetes are overweight or obese, overweight or obesity increases the risk of developing type 2 diabetes and obesity per se is strongly associated with multiple cardiometabolic risk factors. However, many antidiabetic treatments increase body weight. The oral antidiabetic agent, metformin, has been evaluated in hundreds of clinical studies in diverse patient populations during approximately five decades of clinical use. This review summarizes the effects of metformin on body weight, with special reference to studies of longer duration (>/=6 months) as both diabetes and obesity are long-term conditions. Approximately half of studies in drug-naive type 2 diabetic patients demonstrated significant weight loss with metformin compared with baseline or comparator drugs, although pooled analyses have suggested no significant effect versus placebo. Similarly, metformin has been shown to induce weight loss in obese nondiabetic populations, although studies of long duration in this population are scarce. Metformin does appear to mitigate the adverse effects of insulin on body weight. The weight-neutral or weight-sparing effects of metformin constitute a therapeutic advantage in diabetes management where other first-line oral antidiabetic treatments often promote clinically significant weight gain.

Pioglitazone plus glimepiride: a promising alternative in metabolic control

Current approaches to pharmacotherapy of type 2 diabetes focus on two key aspects of hyperglycaemia - insulin secretory dysfunction and insulin resistance. Combining drugs that target both these defects via different mechanisms of action improves long-term glycaemic control and offers a number of additional benefits. A fixed-dose combination of pioglitazone and glimepiride in a single tablet is now available in the US (Duetact(TM)). Both pioglitazone and glimepiride are glucose-lowering agents with distinct mechanisms of action. Pioglitazone is a potent and selective peroxisome proliferator-activated receptor-gamma agonist that improves whole-body insulin sensitivity and augments hepatic glucose uptake. On the other hand, glimepiride acts by releasing insulin from pancreatic beta-cells and improves both first and second phases of insulin secretion. These two therapies have been shown to act synergistically to treat type 2 diabetes - glimepiride therapy achieves rapid reductions in glycated haemaglobin (HbA(1c)), whereas pioglitazone sustains glycaemic control in the longer term. Furthermore, pioglitazone and glimepiride affect a number of pleiotropic markers. In particular, pioglitazone has beneficial effects on the atherogenic diabetic dyslipidaemia that are greater than those seen with rosiglitazone and other oral glucose-lowering agents. This advantage is also seen when comparing pioglitazone and rosiglitazone in combination with glimepiride. In addition, pioglitazone also improves a number of atherosclerotic risk markers that appear to translate into clinical benefits on macrovascular outcomes. Glimepiride may also improve several atherosclerotic risk markers and lipoproteins. This review discusses the potential benefits of combining pioglitazone plus glimepiride on patient compliance, targeting the dual effects of insulin resistance and beta-cell dysfunction and affecting a number of metabolic and cardiovascular parameters.

Thiazolidinediones and the risk of edema: a meta-analysis

The use of thiazolidinediones (TZDs) in the management of type 2 diabetes mellitus (T2DM) has been associated with an increased risk of peripheral edema. A meta-analysis was performed to assess the overall risk for developing edema secondary to TZD. A systematic literature search was conducted using five electronic databases. All prospective, randomized, either placebo-controlled or comparative studies reporting the incidence of edema with TZD therapy were included. Odds ratios were generated by pooling estimates across the studies. The analysis included 26 studies consisting of 15,332 patients with T2DM. The pooled odds ratio for TZD induced edema was 2.26 (95% CI: 2.02-2.53). The results yielded a higher risk for developing edema with rosiglitazone (3.75 [2.70-5.20]) compared to pioglitazone (2.42 [1.90-3.08]). Concordant results persisted with calculations of the adjusted indirect estimate. This meta-analysis demonstrates at least a two-fold increase in the risk for developing edema with a TZD agent. The risk appears to be greater with rosiglitazone than with pioglitazone. Further studies are needed to explore this difference.

Role of metformin in the initiation of pharmacotherapy for type 2 diabetes: an Asian-Pacific perspective

Increases in the prevalence of type 2 diabetes of 30-60% will occur in many Asian-Pacific countries by 2025, driven by urbanisation, sedentary habits and energy-rich diets. Obesity, insulin resistance, metabolic syndrome and diabetes are closely interrelated. Optimal control of diabetes and associated risk factors has reduced the risk of diabetes-related complications. In the UK Prospective Diabetes Study (UKPDS), metformin reduced the risk of macrovascular complications and retrospective analyses have confirmed the efficacy of metformin in improving clinical outcomes in type 2 diabetic patients with a history of cardiovascular disease. This growing body of evidence has led to the recommendation of metformin as optimum initial pharmacotherapy in overweight type 2 diabetic patients. Obesity is less prevalent in the Asian-Pacific population than in Caucasian populations. Nevertheless, metformin has multiple beneficial metabolic effects, which provide sufficient rationale for it to be recommended as the initial oral anti-diabetic pharmacotherapy, alone or in combination, irrespective of body mass index. This recommendation is consistent with global guidelines and regional recommendations for the Asian-Pacific region from the International Diabetes Federation. These recommendations can serve as templates for development of local guidelines for Asian people with diabetes, given the ethnic and cultural diversity within the region.

Factors associated with the effect-size of thiazolidinedione (TZD) therapy on HbA(1c): a meta-analysis of published randomized clinical trials

OBJECTIVE

To examine factors affecting the size of the HbA(1c) response to thiazolidinedione (TZD) therapy.

RESEARCH DESIGN AND METHODS

Meta-analysis of randomized TZD controlled trials which were identified using PubMed, EBSCO and Sci-lit databases and were published in English. Sociodemographic and clinical data were extracted from each trial. HbA(1c) effect size was defined as either a placebo-subtracted change in HbA(1c) or a change in HbA(1c) from baseline. Weighted multivariable regression was used to examine factors associated with changes in HbA(1c). Bootstrapped smearing estimates were computed to obtain reliable estimates of HbA(1c) effect size.

RESULTS

Forty-two trials yielded 60 trial arms which represented 8322 patients treated with thiazolidinediones. Weighted placebo-subtracted change in HbA(1c) was -0.99% +/- 0.02% with an average baseline HbA(1c) of 9.1% +/- 1.0%. Weighted bootstrapped smearing estimate of the placebo-subtracted change in HbA(1c) was -1.02% +/- 0.004%. After controlling for other variables, the baseline HbA(1c) level had a significant negative association with placebo-subtracted HbA(1c) change (p = 0.004) and also with change in HbA(1c) from baseline (p = 0.002). Longer trial duration was associated with greater placebo-subtracted HbA(1c) change (p = 0.01) but not with the change in HbA(1c) from baseline. The multivariable models explained 72% of the variation in placebo-subtracted HbA(1c) change. It was not possible to estimate effects of the run-in period and obesity on TZD effect size.

CONCLUSION

Baseline HbA(1c) and trial duration significantly impacted the effect size of TZD therapy on HbA(1c). Age, gender, duration of diabetes and prior use of anti-diabetic therapy were not associated with the TZD effect size.

Pioglitazone for type 2 diabetes mellitus

BACKGROUND

Diabetes has long been recognised as a strong, independent risk factor for cardiovascular disease, a problem which accounts for approximately 70% of all mortality in people with diabetes. Prospective studies show that compared to their non-diabetic counterparts, the relative risk of cardiovascular mortality for men with diabetes is two to three and for women with diabetes is three to four. The two biggest trials in type 2 diabetes, the United Kingdom Prospective Diabetes Study (UKPDS) and the University Group Diabetes Program (UGDP) study did not reveal a reduction of cardiovascular endpoints through improved metabolic control. Theoretical benefits of the newer peroxisome proliferator activated receptor gamma (PPAR-gamma) activators like pioglitazone on endothelial function and cardiovascular risk factors might result in fewer macrovascular disease events in people with type 2 diabetes mellitus.

OBJECTIVES

To assess the effects of pioglitazone in the treatment of type 2 diabetes.

SEARCH STRATEGY

Studies were obtained from computerised searches of MEDLINE, EMBASE and The Cochrane Library. The last search was conducted in August 2006.

SELECTION CRITERIA

Studies were included if they were randomised controlled trials in adult people with type 2 diabetes mellitus and had a trial duration of at least 24 weeks.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Pooling of studies by means of random-effects meta-analysis could be performed for adverse events only.

MAIN RESULTS

Twenty-two trials which randomised approximately 6200 people to pioglitazone treatment were identified. Longest duration of therapy was 34.5 months. Published studies of at least 24 weeks pioglitazone treatment in people with type 2 diabetes mellitus did not provide convincing evidence that patient-oriented outcomes like mortality, morbidity, adverse effects, costs and health-related quality of life are positively influenced by this compound. Metabolic control measured by glycosylated haemoglobin A1c (HbA1c) as a surrogate endpoint did not demonstrate clinically relevant differences to other oral antidiabetic drugs. Occurrence of oedema was significantly raised. The results of the single trial with relevant clinical endpoints (Prospective Pioglitazone Clinical Trial In Macrovascular Events--PROactive study) have to be regarded as hypothesis-generating and need confirmation.

AUTHORS' CONCLUSIONS

Until new evidence becomes available, the benefit-risk ratio of pioglitazone remains unclear. Different therapeutic indications for pioglitazone of the two big U.S. and European drug agencies should be clarified to reduce uncertainties amongst patients and physicians.

Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus

BACKGROUND

Metformin is an oral anti-hyperglycemic agent used in the treatment of type 2 diabetes mellitus. The results of the UK Prospective Diabetes Study indicate that metformin treatment is associated with a reduction in total mortality compared to other anti-hyperglycemic treatments. Metformin, however, is thought to increase the risk of lactic acidosis, and is considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age.

OBJECTIVES

To assess the incidence of fatal and nonfatal lactic acidosis with metformin use compared to placebo and other glucose-lowering treatments in patients with type 2 diabetes mellitus. A secondary objective was to evaluate the blood lactate levels for those on metformin treatment compared to placebo or non-metformin therapies.

SEARCH STRATEGY

A search was performed of The Cochrane Library (up to 8/2005), MEDLINE (up to 8/2005), EMBASE (up to 11/2000), OLD MEDLINE, and REACTIONS (up to 8/2005), in order to identify all studies of metformin treatment from 1966 to August 2005. The Cumulated Index Medicus was used to search relevant articles from 1959 to 1965. The search was augmented by scanning references of identified articles, and by contacting principal investigators. Date of latest search: August 2005.

SELECTION CRITERIA

Prospective trials in patients with type 2 diabetes that lasted longer than one month were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy. Observational cohort studies of metformin treatment lasting greater than one month were also included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials to be included, assessed study quality and extracted data. The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for placebo or other treatments. The upper limit for the true incidence of cases in the metformin and non-metformin groups were calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed effect model for continuous data.

MAIN RESULTS

Pooled data from 206 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 47,846 patient-years of metformin use or in 38,221 patients-years in the non-metformin group. Using Poisson statistics with 95% confidence intervals the upper limit for the true incidence of metformin-associated lactic acidosis was 6.3 cases per 100,000 patient-years, and the upper limit for the true incidence of lactic acidosis in the non-metformin group was 7.8 cases per 100,000 patient-years. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to placebo or other non-biguanide therapies. The mean lactate levels were slightly lower for metformin treatment compared to phenformin (WMD -0.75 mmol/L, 95% CI -0.86 to -0.15).

AUTHORS' CONCLUSIONS

There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments if prescribed under the study conditions.