Comparison of glycaemic control over 1 year with pioglitazone or gliclazide in patients with Type 2 diabetes

Effect of insulin secretagogues on major cardiovascular events and all-cause mortality: A meta-analysis of randomized controlled trials

BACKGROUND AND AIM

In 2019, the Italian Society of Diabetology and the Italian Association of Clinical Diabetologists nominated an expert panel to develop guidelines for drug treatment of type 2 diabetes. This expert panel, after identifying the effects of glucose-lowering agents on major adverse cardiovascular events (MACEs) and all-cause mortality as critical outcomes, decided to perform a systematic review and meta-analysis on the effect of insulin secretagogues (sulfonylureas and glinides) with this respect.

METHODS AND RESULTS

A MEDLINE database search was performed to identify all RCTs, up to January 1st, 2020, with duration≥52 weeks, in which insulin secretagogues (glibenclamide, gliclazide, glimepiride, glipizide, chlorpropamide, repaglinide, nateglinide) were compared with either placebo or active comparators. The principal endpoints were MACE (restricted for RCT reporting MACEs within their outcomes) and all-cause mortality (irrespective of the inclusion of MACEs among the pre-specified outcomes). Mantel-Haenszel odds ratio (MH-OR) with 95% Confidence Interval (95% CI) was calculated for all the endpoints considered. Fourteen RCTs were included in the analysis for MACEs (919 in insulin secretagogues and 1,087 in control group). Insulin secretagogues were not significantly associated with an increased risk of MACEs in comparison with controls (MH-OR 1.08 [95% CI 0.96, 1.22], p = 0.20). When considering the 48 RCTs fulfilling criteria for inclusion in the analysis on all-cause mortality, insulin secretagogues were associated with a significantly increased risk of all-cause mortality (MH-OR 1.11 [1.00, 1.23], p = 0.04).

CONCLUSIONS

This meta-analysis suggests that insulin secretagogues are associated with an increased risk of all-cause mortality when compared with placebo or other anti-hyperglycaemic drugs.

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.

Inhibition of the Mitochondrial Pyruvate Carrier by Tolylfluanid

Several recent studies have suggested that compounds known as endocrine-disrupting chemicals (EDCs) can promote obesity by serving as ligands for nuclear receptors, including the peroxisome proliferator-activated receptor γ (PPARγ) and the glucocorticoid receptor (GR). Thiazolidinedione insulin sensitizers, which act as ligands for PPARγ, also interact with and regulate the activity of the mitochondrial pyruvate carrier (MPC). We evaluated whether several EDCs might also affect MPC activity. Most of the EDCs evaluated did not acutely affect pyruvate metabolism. However, the putative endocrine disruptors tributyltin (TBT) and tolylfluanid (TF) acutely and markedly suppressed pyruvate metabolism in isolated mitochondria. Using mitochondria isolated from brown adipose tissue in mice with adipocyte-specific deletion of the MPC2 protein, we determined that the effect of TF on pyruvate metabolism required MPC2, whereas TBT did not. We attempted to determine whether the obesogenic effects of TF might involve MPC2 in adipose tissue. However, we were unable to replicate the published effects of TF on weight gain and adipose tissue gene expression in wild-type or fat-specific MPC2 knockout mice. Treatment with TF modestly enhanced adipogenic gene expression in vitro but had no effect on GR activation or phosphorylation in cultured cells. These data suggest that TF may affect mitochondrial pyruvate metabolism via the MPC complex but also call into question whether this compound affects GR activity and is obesogenic in mice.

PPARγ and Its Role in Cardiovascular Diseases

Peroxisome proliferator-activated receptor Gamma (PPARγ), a ligand-activated transcription factor, has a role in various cellular functions as well as glucose homeostasis, lipid metabolism, and prevention of oxidative stress. The activators of PPARγ are already widely used in the treatment of diabetes mellitus. The cardioprotective effect of PPARγ activation has been studied extensively over the years making them potential therapeutic targets in diseases associated with cardiovascular disorders. However, they are also associated with adverse cardiovascular events such as congestive heart failure and myocardial infarction. This review aims to discuss the role of PPARγ in the various cardiovascular diseases and summarize the current knowledge on PPARγ agonists from multiple clinical trials. Finally, we also review the new PPARγ agonists under development as potential therapeutics with reduced or no adverse effects.

Is gliclazide a sulfonylurea with difference? A review in 2016

Sulfonylureas (SUs) remain the most commonly prescribed drug after metformin in the treatment of type 2 diabetes (T2DM), despite the availability of several newer agents. The primary reason of SUs being most popular is their quick glycemic response, time-tested experience and least cost. Although SUs are one amongst the several other second line agents after metformin in all major guidelines, the new Dutch type 2 guidelines specifically advise gliclazide as the preferred second line drug instead of SUs as a class. The World Health Organization (WHO) has also included gliclazide in their Model List of Essential Medicines 2013 motivated by its safety data in elderly patients. Specifically advising gliclazide may have been based on emerging evidence suggesting cardiovascular neutrality of gliclazide over other SUs. This prompted us to do a literature review of gliclazide efficacy and safety data compared to other SUs as well as oral anti-diabetic drugs.

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.

Safety and efficacy of gliclazide as treatment for type 2 diabetes: a systematic review and meta-analysis of randomized trials

Objective and Design

Gliclazide has been associated with a low risk of hypoglycemic episodes and beneficial long-term cardiovascular safety in observational cohorts. The aim of this study was to assess in a systematic review and meta-analysis of randomized controlled trials the safety and efficacy of gliclazide compared to other oral glucose-lowering agents (PROSPERO2013:CRD42013004156)

Data Sources

Medline, EMBASE, Clinicaltrials.gov, Trialregister.nl, Clinicaltrialsregister.eu and the Cochrane database.

Selection

Included were randomized studies of at least 12 weeks duration with the following outcomes: HbA1c change, incidence of severe hypoglycemia, weight change, cardiovascular events and/or mortality when comparing gliclazide with other oral blood glucose lowering drugs. Bias was assessed with the Cochrane risk of bias tool. The inverse variance random effects model was used.

Results

Nineteen trials were included; 3,083 patients treated with gliclazide and 3,155 patients treated with other oral blood glucose lowering drugs. There was a considerable amount of heterogeneity between and bias in studies. Compared to other glucose lowering agents except metformin, gliclazide was slightly more effective (−0.13% (95%CI: −0.25, −0.02, I² 55%)). One out of 2,387 gliclazide users experienced a severe hypoglycemic event, whilst also using insulin. There were 25 confirmed non-severe hypoglycemic events (2.2%) in 1,152 gliclazide users and 22 events (1.8%) in 1,163 patients in the comparator group (risk ratio 1.09 (95% CI: 0.20, 5.78, I² 77%)). Few studies reported differences in weight and none were designed to evaluate cardiovascular outcomes.

Conclusions

The methodological quality of randomized trials comparing gliclazide to other oral glucose lowering agents was poor and effect estimates on weight were limited by publication bias. The number of severe hypoglycemic episodes was extremely low, and gliclazide appears at least equally effective compared to other glucose lowering agents. None of the trials were designed for evaluating cardiovascular outcomes, which warrants attention in future randomized trials.

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.

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.

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.

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.

Comparing the actions of older and newer therapies on body weight: to what extent should these effects guide the selection of antidiabetic therapy?

BACKGROUND

Type 2 diabetes patients are usually overweight or obese. Further weight gain induced by antidiabetic treatment should be avoided if possible. Much attention has been focussed recently on the potential for GLP-1 mimetics, in particular, to reduce weight.

AIMS

Effects on weight are but one of several important criteria in selecting antidiabetic therapy, however. This review explores the effects on weight of older classes of antidiabetic agents (metformin, sulfonylureas, thiazolidinediones) and the newer drugs acting via the GLP-1 system. Other aspects of their therapeutic profiles and current therapeutic use are reviewed briefly to place effects on weight within a broader context.

FINDINGS

Comparative trials demonstrated weight neutrality or weight reduction with metformin, and weight increases with a sulfonylurea or thiazolidinedione. There was no clinically significant change in weight with DPP-4 inhibitors and a small and variable decrease in weight (about 3 kg or less) with GLP-1 mimetics. Improved clinical outcomes have been demonstrated for metformin and a sulfonylurea (cardiovascular and microvascular benefits, respectively, in the UK Prospective Diabetes Study), and secondary endpoints improved modestly with pioglitazone in the PROactive trial. No outcome benefits have been demonstrated to date with GLP-1-based therapies, and these agents exert little effect on cardiovascular risk factors. Concerns remain over long-term safety of these agents and this must be weighed against any potential benefit on weight management.

CONCLUSIONS

Considering effects on weight within the overall risk-benefit profile of antidiabetic therapies, metformin continues to justify its place at the head of current management algorithms for type 2 diabetes, due to its decades-long clinical evidence base, cardiovascular outcome benefits and low cost.

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.

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.

The backbone of oral glucose-lowering therapy: time for a paradigm shift?

The complex array of metabolic abnormalities associated with type 2 diabetes provides a number of new targets for therapeutic intervention. Although the established oral glucose-lowering therapies, metformin and the sulfonylureas, continue to provide the backbone of therapeutic approaches, the thiazolidinediones (TZDs) also play an important role. Further, a new class of oral agents, the dipeptidyl peptidase-IV (DPP-IV) inhibitors, has recently become available with apparent utility in decreasing postprandial glucose excursions. This review examines how the TZDs and the DPP-IV inhibitors might integrate into current treatment strategies, considering not only glycemic goals, but also longer-term benefits such as durability of glycemic control, effect on metabolic parameters and cardiovascular outcomes. A practical approach is taken, reflecting potential clinical situations in which therapeutic intervention is required.

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.

Pioglitazone and sulfonylureas: effectively treating type 2 diabetes

Type 2 diabetes is characterised by a gradual decline in glycaemic control and progression from oral glucose-lowering monotherapy to combination therapy and exogenous insulin therapy. Functional decline of the insulin-secreting beta-cells is largely responsible for the deterioration in glycaemic control. Preservation of beta-cell functionality, in addition to maintaining glycaemic control and reducing insulin resistance, is now regarded as a key target for long-term management strategies. Early, aggressive intervention with combination therapy is emerging as a valid approach to optimise long-term outcomes and combining agents with differing modes of action and secondary effect profiles should prove valuable. Sulfonylureas and thiazolidinediones exert their glucose-lowering effect through differing mechanisms of action - the sulfonylureas by stimulating insulin secretion, whereas the thiazolidinediones are insulin sensitisers. Both agents offer excellent improvements in glycaemic control when given as monotherapy or in combination. The thiazolidinediones protect beta-cell structural and functional integrity and functionality and complement the sulfonylureas by inducing and maintaining improvements in insulin resistance, the abnormal lipid profile associated with type 2 diabetes and other cardiovascular risk factors. Thus, there is a strong rationale to support the addition of thiazolidinediones to sulfonylureas as a treatment option for type 2 diabetes. This combination may be particularly effective in the early stages of the disease when beta-cell function is at its highest, allowing maximal benefit to be obtained from the insulin secretion-promoting abilities of the sulfonylureas and the beta-cell-protective effects of the thiazolidinediones.

Long-term effects of pioglitazone versus gliclazide on hepatic and humoral coagulation factors in patients with type 2 diabetes

This study compared the long-term effects of pioglitazone and gliclazide on the production of coagulation factors in patients with type 2 diabetes. Patients (n=283) with glycosylated haemoglobin > 7.5% were randomised to receive either pioglitazone (30-45 mg/day) or gliclazide (80-320 mg/day) for one year. Coagulation factors were measured at baseline and at six and 12 months. While both pioglitazone and gliclazide induced a comparable improvement in glycaemic control, only pioglitazone improved insulin sensitivity. Pioglitazone significantly (p < or = 0.001) decreased circulating levels of von Willebrand factor (-9.7%, -9.4%) and plasminogen activator inhibitor-1 (-16.8 ng/ml, -12.3 ng/ml), and increased levels of antithrombin-III (+1.3 mg/dL, +1.5 mg/dL) after six and 12 months, respectively. The beneficial effects of pioglitazone on glycaemic control, lipid homeostasis, and coagulation and thrombosis, may improve vascular outcomes in patients with type 2 diabetes.

Effects of pioglitazone in combination with metformin or a sulfonylurea compared to a fixed-dose combination of metformin and glibenclamide in patients with type 2 diabetes

BACKGROUND

This study was designed to compare the effectiveness of co-administration of pioglitazone with metformin or a sulfonylurea (SU), with a fixed-dose combination of metformin and glibenclamide on glycemic control and beta-cell function in patients with type 2 diabetes.

METHODS

Patients (n = 250) treated with metformin (<or=3 g/day) or an SU as monotherapy for >3 months and with glycosylated hemoglobin (HbA(1c)) between 7.5% and 11% inclusive were randomized to receive either pioglitazone (15-30 mg/day) as add-on therapy to metformin or an SU or a fixed-dose combination of metformin (400 mg) and glibenclamide (2.5 mg) (up to three tablets per day) for 6 months. HbA(1c) and fasting plasma glucose (FPG) were measured at baseline and 2, 4, and 6 months. C-peptide levels were measured at baseline and 6 months, and post-challenge glucose and insulin responses were measured.

RESULTS

After 6 months, pioglitazone-based and fixed-dose metformin + glibenclamide resulted in similar reductions in HbA(1c) (-1.11% vs. -1.29%, respectively; P = 0.192) and FPG (-2.13 vs. -1.81 mmol/L, respectively; P = 0.370). Patients treated with pioglitazone for 6 months had significantly reduced C-peptide levels compared with baseline (-0.09 nmol/L, P = 0.001), while patients receiving fixed-dose metformin + glibenclamide combination had slightly increased C-peptide levels (+0.04 nmol/L, P = 0.08). Pioglitazone treatment also improved post-challenge insulin responses.

CONCLUSIONS

Co-administration of pioglitazone with metformin or an SU is an effective alternative to fixed-dose metformin + glibenclamide combination for patients with type 2 diabetes. The complementary effects of pioglitazone with either metformin or an SU may also have the potential to preserve beta-cell function and delay the progression of type 2 diabetes.

Effect of pioglitazone on the drivers of cardiovascular risk in type 2 diabetes

The prevalence of type 2 diabetes and its associated mortality and morbidity are continuing to increase across the world. People with type 2 diabetes typically have a cluster of risk factors for cardiovascular disease, including hyperglycaemia, hypertension and lipid abnormalities, which contribute to the high cardiovascular morbidity and mortality in these patients. Targets for glycosylated haemoglobin, lipids and blood pressure are becoming more stringent, and most patients will require multiple therapies to maximally reduce cardiovascular risk. In a large randomised, controlled, long-term cardiovascular outcomes study pioglitazone showed durable glycaemic control, a powerful insulin-sparing effect and changes in the lipid profile associated with reduced cardiovascular risk. This article reviews these metabolic findings in the context of previous randomised, controlled studies for pioglitazone and discusses whether the integration of this agent into the treatment regimen of appropriate patient groups has the potential to improve cardiovascular outcomes in type 2 diabetes.

Glycemic control and treatment failure with pioglitazone versus glibenclamide in type 2 diabetes mellitus: a 42-month, open-label, observational, primary care study

BACKGROUND

Insulin resistance and declining beta-cell function are the core defects in type 2 diabetes mellitus. It has been suggested that deteriorating glycemic control is related to baseline hemoglobin A(1c) (HbA(1c)) values and remaining beta-cell function.

PATIENTS AND METHODS

We report glycemic data from a 3.5-year, open-label, observational, primary care study comparing 30 mg/day pioglitazone with 3.5 mg/day glibenclamide add-on to stable metformin monotherapy in 500 patients with type 2 diabetes. Insulin commencement was considered for patients with HbA(1c) > or = 8.0% or when vascular complications occurred. The change in HbA(1c) compared with baseline and the difference in time to failure to maintain glycemic control were calculated.

RESULTS

At endpoint, HbA(1c) had decreased by 1.0% in the pioglitazone group (p < 0.005) and by 0.6% in the glibenclamide group (p < 0.05). Annual progression rates to insulin treatment were 6.6% (pioglitazone) and 16.4% (glibenclamide; p < 0.001 between-group difference). Mean weight increases of 3.5 +/- 0.42 kg in the pioglitazone group and 3.3 +/- 0.38 kg in the glibenclamide group were noted. Overall, both treatments were well tolerated.

CONCLUSIONS

Pioglitazone add-on to metformin revealed significant benefits in long-term glycemic control compared with glibenclamide. This difference may be explained by a large between-group difference in HOMA-S, which was shown to correlate significantly to the change in HbA(1c). This suggests that a strategy to reduce insulin resistance to lower the burden of the beta-cell is superior to treatment with glibenclamide.