A 1-year multicenter randomized double-blind comparison of repaglinide and glyburide for the treatment of type 2 diabetes. Dutch and German Repaglinide Study Group

Drug Therapies for Diabetes

The treatment of type 2 diabetes (T2D) necessitates a multifaceted approach that combines behavioral and pharmacological interventions to mitigate complications and sustain a high quality of life. Treatment encompasses the management of glucose levels, weight, cardiovascular risk factors, comorbidities, and associated complications through medication and lifestyle adjustments. Metformin, a standard in diabetes management, continues to serve as the primary, first-line oral treatment across all age groups due to its efficacy, versatility in combination therapy, and cost-effectiveness. Glucagon-like peptide-1 receptor agonists (GLP-1 RA) offer notable benefits for HbA1c and weight reduction, with significant cardiovascular benefits. Sodium-glucose cotransporter inhibitors (SGLT-2i) lower glucose levels independently of insulin while conferring notable benefits for cardiovascular, renal, and heart-failure outcomes. Combined therapies emphasizing early and sustained glycemic control are promising options for diabetes management. As insulin therapy remains pivotal, metformin and non-insulin agents such as GLP-1 RA and SGLT-2i offer compelling options. Notably, exciting novel treatments like the dual GLP-1/ glucose-dependent insulinotropic polypeptide (GIP) agonist show promise for substantially reducing glycated hemoglobin and body weight. This comprehensive review highlights the evolving landscape of pharmacotherapy in diabetes, the drugs currently available for treating diabetes, their effectiveness and efficacy, the impact on target organs, and side effects. This work also provides insights that can support the customization of treatment strategies.

Penetration of new antidiabetic medications in East Asian countries and the United States: A cross-national comparative study

BACKGROUND

The number of patients with diabetes is increasing particularly in Asia-Pacific region. Many of them are treated with antidiabetics. As the basis of the studies on the benefit and harm of antidiabetic drugs in the region, the information on patterns of market penetration of new classes of antidiabetic medications is important in providing context for subsequent research and analyzing and interpreting results.

METHODS

We compared penetration patterns of dipeptidyl peptidase-4 (DPP-4) inhibitors in Taiwan, Hong Kong, Japan, and the United States. We used the Taiwan National Health Insurance Research Database, a random sample of the Hong Kong Clinical Data Analysis and Reporting System, the Japan Medical Data Center database, and a 5% random sample of the US Medicare database converted to the Observational Medical Outcomes Partnership's Common Data Model to identify new users of oral antidiabetic medications. We standardized prevalence and incidence rates of medication use by age and sex to those in the 2010 Taiwanese population. We compared age, sex, comorbid conditions, and concurrent medications between new users of DPP-4 inhibitors and biguanides.

RESULTS

Use of DPP-4 inhibitors 1 year after market entry was highest in Japan and lowest in Hong Kong. New users had more heart failure, hyperlipidemia, and renal failure than biguanide users in Taiwan, Hong Kong, and the United States while the proportions were similar in Japan. In a country with low penetration of DPP-4 inhibitors (eg, Hong Kong), users had diabetes with multiple comorbid conditions compared with biguanidine users. In a country with high penetration (eg, Japan), the proportion of users with comorbid conditions was similar to that of biguanide users.

CONCLUSIONS

We observed a marked difference of the penetration patterns of newly marketed antidiabetics in different countries in Asia. Those results will provide the basic information useful in the future studies.

Oral Antidiabetic Agents: A Comparative Review

Type 2 diabetes mellitus is a chronic disease characterized by insulin resistance, impaired insulin secretion, and/or increased hepatic glucose production. The mainstays of drug treatment are the oral antidiabetic agents. Insulin is usually reserved for patients who do not achieve fasting plasma glucose or A1C goals with or cannot tolerate the oral antidiabetic agents. There are 5 classes of oral antidiabetic agents available in the United States: sulfonylureas, biguanides, alpha-glucosidase inhibitors, thiazolidinediones, and nonsulfonylurea secretagogues. They have differences and similarities with respect to their pharmacology and role in diabetes. This article reviews the pharmacology, efficacy, safety, and selection of the oral agents used to treat type 2 diabetes mellitus.

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.

Comparison of efficacy and safety of once- versus twice-daily insulin detemir added on to oral antidiabetics in insulin-naive type 2 diabetes patients: 24-week, crossover, treat to target trial in a single center

AIM

To compare once- versus twice-daily insulin detemir added on OADS therapy in insulin-naive type 2 diabetes patients in terms of efficacy and safety.

METHODS

An open-label study performed at a single center, comprised a randomized, crossover 24 week with insulin-naive type 2 diabetes patients. Insulin detemir was initiated with mean 0.12 U/kg in all patients (Group I once-daily, Group II twice-daily) and titrated for 24 week.

RESULTS

A total of 50 patients completed the study (Group I n:25, Group II n:25). With use of once- and twice-daily insulin, HbA1c values were decreased by 1.8% (±2.0) and 1.5% (±1.4) within the first 12 weeks (p<0.01), whereas increased by 0.21% (±0.7) and 0.14% (±0.8) in the second 12 weeks (p>0.05). The increases in the insulin doses were found as 0.22 U/kg and 0.35 U/kg with once- and twice-daily insulin use, respectively (p:0.04). Although minor hypoglycemic events were similar in both groups in the first 12 weeks, 2-fold increase was found in the patients shifting from once- to twice-daily dose. Within the first and second periods, the body weight of the patients was observed an increase of 0.4 and 1.6 kg with once-daily dose, whereas a decrease of 0.1 and 2.1 kg in the twice-daily dose, in the same period.

CONCLUSION

Once-daily use of insulin detemir up to 0.4 U/kg was found to have similar efficacy and safety as twice-daily use. Twice dose use of insulin did not provide a prominent glycemic control advantage on 1.5-fold higher use of insulin.

Treating the elderly diabetic patient: special considerations

The prevalence of diabetes is rising in the >65 year-old group. The challenge of defining the goals of therapy arises from the heterogeneity of the aging process and the sparse clinical data in this patient population. In light of these challenges, the clinician should be aware of the pitfalls of caring for the older diabetic patient and prioritize an individualized treatment plan to ensure an optimal glycemic control, without placing the patient at unnecessary risk. We present a review of the current guidelines and literature that deal specifically with the treatment of the older diabetic patient in order to establish the principles of treatment in this age group and help the clinician make decisions regarding the care of these patients.

Optimal Pharmacologic Treatment Strategies in Obesity and Type 2 Diabetes

The prevalence of obesity has increased to pandemic levels worldwide and is related to increased risk of morbidity and mortality. Metabolic comorbidities are commonly associated with obesity and include metabolic syndrome, pre-diabetes, and type 2 diabetes. Even if the prevalence of obesity remains stable until 2030, the anticipated numbers of people with diabetes will more than double as a consequence of population aging and urbanization. Weight reduction is integral in the prevention of diabetes among obese adults with pre-diabetes. Lifestyle intervention and weight reduction are also key in the management of type 2 diabetes. Weight loss is challenging for most obese patients, but for those with diabetes, it can pose an even greater challenge due to the weight gain associated with many treatment regimens. This article will review optimal treatment strategies for patients with comorbid obesity and type 2 diabetes. The role of anti-obesity agents in diabetes will also be reviewed. This literature review will provide readers with current strategies for the pharmacologic treatment of obesity and diabetes with a focus on the weight outcomes related to diabetes treatments.

Complications of diabetes therapy

Current strategies for the treatment of type 2 diabetes mellitus promote individualized plans to achieve target glucose levels on a patient-by-patient basis while minimizing treatment related risks. Maintaining glycemic control over time is a significant challenge because of the progressive nature of diabetes as a result of declining β-cell function. This article identifies complications of non-insulin treatments for diabetes. The major classes of medications are reviewed with special focus on target population, mechanism of action, effect on weight, cardiovascular outcomes and additional class-specific side effects including effects on bone. Effects on β-cell function are also highlighted.

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.

Dose selection using a semi-mechanistic integrated glucose-insulin-glucagon model: designing phase 2 trials for a novel oral glucokinase activator

Selecting dosing regimens for phase 2 studies for a novel glucokinase activator LY2599506 is challenging due to the difficulty in modeling and assessing hypoglycemia risk. A semi-mechanistic integrated glucose-insulin-glucagon (GIG) model was developed in NONMEM based on pharmacokinetic, glucose, insulin, glucagon, and meal data obtained from a multiple ascending dose study in patients with Type 2 diabetes mellitus treated with LY2599506 for up to 26 days. The series of differential equations from the NONMEM model was translated into an R script to prospectively predict 24-h glucose profiles following LY2599506 treatment for 3 months for a variety of doses and dosing regimens. The reduction in hemoglobin A1c (HbA1c) at the end of the 3-month treatment was estimated using a transit compartment model based on the simulated fasting glucose values. Two randomized phase 2 studies, one with fixed dosing and the other employing conditional dose titration were conducted. The simulation suggested that (1) Comparable HbA1c lowering with lower hypoglycemia risk occurs with titration compared to fixed-dosing; and (2) A dose range of 50-400 mg BID provides either greater efficacy or lower hypoglycemia incidence or both than glyburide. The predictions were in reasonable agreement with the observed clinical data. The model predicted HbA1c reduction and hypoglycemia risk provided the basis for the decision to focus on the dose-titration trial and for the selection of doses for the demonstration of superiority of LY2599506 to glyburide. The integrated GIG model represented a valuable tool for the evaluation of hypoglycemia incidence.

Efficacy and safety profile evaluation of acarbose alone and in association with other antidiabetic drugs: a systematic review

BACKGROUND

Epidemiologic studies have revealed that postprandial hyperglycemia significantly contributes to high glycated hemoglobin concentrations and could be linked to the development of chronic diabetic complications.

OBJECTIVE

The purpose of our review was to evaluate the clinical efficacy and safety profile of treatment with acarbose alone and combined with other antidiabetic drugs.

METHODS

A systematic search strategy was developed to identify randomized controlled trials included in MEDLINE and the Cochrane Register of Controlled Trials. The terms acarbose, α-glucosidase inhibitors, type 2 diabetes, adverse events, combination therapy, and postprandial glucose were incorporated into an electronic search strategy that included the Dickersin filter for randomized controlled trials. To qualify for inclusion, clinical trials had to be randomized trials comparing treatment with acarbose at any dosage with any other antidiabetic drug in patients with type 2 diabetes mellitus or impaired glucose tolerance. Eligible trials had to present results on glycemic control or adverse events. Trial participants needed to be affected by type 2 diabetes mellitus or have impaired glucose tolerance, and the intervention had to include acarbose at any dosage as monotherapy or combined with other antidiabetic drugs. A validated 3-item scale was used to evaluate the overall reporting quality of the trials selected for inclusion in the present review. Nineteen trials were included.

RESULTS

Treatment with acarbose significantly reduced glycated hemoglobin levels when given as monotherapy and as an add-on to other antidiabetic drug treatment (P < 0.0001). Acarbose treatment was effective in patients with uncontrolled type 2 diabetes and in patients with apparently good metabolic control owing to its positive effect on postprandial hyperglycemia (P < 0.0001). Treatment with acarbose seemed to improve the lipid profile (P < 0.05), reduce circulating levels of cell adhesion molecules (P < 0.05), reduce intima-media thickness progression (P = 0.01), and reverse impaired glucose tolerance to normal glucose tolerance (P < 0.0001).

CONCLUSIONS

When current therapy is not adequate to obtain glycemic control, acarbose could be an option as monotherapy and as an add-on to other antidiabetic drug treatment, especially when postprandial hyperglycemia is the main concern. Long-term studies are needed to determine whether the effects observed with acarbose use are maintained over the years.

Repaglinide: a review of its use in type 2 diabetes mellitus

Oral repaglinide (GlucoNorm®; NovoNorm®; Prandin®; Surepost®) is a rapid-acting insulin secretagogue that lowers postprandial glucose (PPG) excursions by targeting early-phase insulin release, with reductions in PPG considered to be important in reducing long-term cardiovascular complications of diabetes mellitus. Repaglinide, a carbamoylbenzoic acid derivative, is chemically related to the meglitinide class of insulin secretagogues, but unrelated to the sulfonylurea insulin secretagogues. Meglitinides, including repaglinide, have a distinct binding site at the β-cell membrane, which differs from that of sulfonylureas, and corresponds to greater insulinotropic effects with repaglinide than with glibenclamide and/or glimepiride and a more rapid onset of action in in vitro and in vivo studies. This article reviews the clinical efficacy and tolerability of oral repaglinide in the treatment of patients with type 2 diabetes and provides an overview of its pharmacological properties. In well designed clinical trials of up to 52 weeks' duration and in the clinical practice setting, recommended dosages of repaglinide (0.5-4 mg three times daily up to 30 minutes prior to a meal) provided effective glycaemic control and were generally well tolerated in treatment-naive or -experienced adult patients with type 2 diabetes, including elderly patients and those with renal impairment. Furthermore, as monotherapy or in combination with other oral antihyperglycaemic drugs, repaglinide was at least as effective as other oral antihyperglycaemic drugs at improving or maintaining glycaemic control, with a tolerability profile that was generally similar to that of sulfonylurea drugs and nateglinide. Thus, repaglinide remains an effective option for the management of patients with type 2 diabetes.

Repaglinide/metformin fixed-dose combination to improve glycemic control in patients with type 2 diabetes: an update

Type 2 diabetes is a progressive disease associated with high levels of morbidity and mortality and for which there is both a large and growing prevalence worldwide. Lifestyle advice plus metformin is commonly recommended initially to manage hyperglycemia and to minimize the risk of vascular complications. However, additional agents are required when glycemic targets cannot be achieved or maintained due to the progressive nature of the disease. Repaglinide/metformin fixed-dose combination (FDC) therapy (PrandiMet(®); Novo Nordisk, Bagsværd, Denmark) has been approved for use in the USA. This FDC is a rational second-line therapy given the complementary mechanisms of action of the components. Repaglinide is a rapidly absorbed, short-acting insulin secretagogue targeting postprandial glucose excursions; metformin is an insulin sensitizer with a longer duration of action that principally regulates basal glucose levels. A pivotal, 26-week, randomized study with repaglinide/metformin FDC therapy has been conducted in patients experiencing suboptimal control with previous oral antidiabetes therapy. Repaglinide/metformin FDC improved glycemic control and weight neutrality without adverse effects on lipid profiles. There were no major hypoglycemic episodes and patients expressed greater satisfaction with repaglinide/metformin FDC than previous treatments. Repaglinide/metformin FDC is expected to be more convenient than individual tablets for patients taking repaglinide and metformin in loose combination, and it is expected to improve glycemic control in patients for whom meglitinide or metformin monotherapies provide inadequate control.

Combination therapy for patients with Type 2 diabetes: repaglinide in combination with metformin

In patients with Type 2 diabetes mellitus (T2DM), adequate glycemic control is a critical factor in reducing long-term micro- and macro-vascular complications. Traditionally, the approach is to initiate monotherapy first, followed by combination therapy that targets two main defects in T2DM. Repaglinide, a rapidly acting insulin secretagog, stimulates insulin secretion via closure of ATP-dependent potassium channels on the cell membrane of β-cells. Repaglinide is ideally used at mealtime to reduce postprandial glucose levels, thus lowering the 24-h blood glucose profile and improving HbA1c levels. Metformin is an insulin sensitizer that effectively acts against insulin resistance, one of the predominant metabolic defects in T2DM. A combination of repaglinide and metformin is indicated as an adjunct to diet and exercise to improve glycemic control in adults with T2DM. When monotherapy with oral antidiabetic agents fails, combination therapy with repaglinide plus metformin has been demonstrated to be safe and effective in the treatment of T2DM.

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.

Treatment Considerations for Diabetes: A Pharmacist’s Guide to Improving Care in the Elderly

The management of diabetes in elderly patients has many nuances that are important to the pharmacist, regardless of his or her practice setting. General guidelines and treatment modalities applied to the younger population cannot necessarily be applied to the elderly population and in most cases, should be tailored to meet their needs. The purpose of this article is to gain a better understanding of the complex nature of diabetes and management in the elderly by (1) reviewing the pathogenesis and pathophysiology of diabetes in the patients, (2) understanding complications and geriatric syndromes that may affect management of diabetes, (3) becoming familiar with nationally accepted diabetes care guidelines in the elderly, (4) reviewing recent literature pertaining to management of diabetes, and (5) reviewing medications (including newer agents) to treat diabetes in the elderly.

Postprandial hyperglycemia as an etiological factor in vascular failure

Postprandial hyperglycemia is characterized by hyperglycemic spikes that induce endothelial dysfunction, inflammatory reactions and oxidative stress, which may lead to progression of atherosclerosis and occurrence of cardiovascular events. Emerging data indicate that postprandial hyperglycemia or even impaired glucose tolerance may predispose to progression of atherosclerosis and cardiovascular events. There is evidence that postprandial hyperglycemia, but not fasting hyperglycemia, independently predicts the occurrence of cardiovascular events. We proposed a concept of 'vascular failure' as a comprehensive syndrome of vascular dysfunction extending from risk factors to advanced atherosclerotic disease. Postprandial hyperglycemia is therefore one of the very important pathophysiological states contributing to vascular failure. Accordingly, controlling postprandial hyperglycemia should be the focus of future clinical investigation as a potential target for preventing vascular failure.

Oral combination therapy: repaglinide plus metformin for treatment of type 2 diabetes

Type 2 diabetes is characterized by decreases in insulin secretion and insulin sensitivity. Several classes of oral antidiabetic medications are currently approved for the treatment of type 2 diabetes. A stepwise treatment approach from monotherapy to combination therapy is traditionally used; however, the frequency of treatment failure with monotherapy has resulted in a move towards earlier treatment with combination therapies that target the two principal defects in glycaemic control. One such combination regimen is repaglinide (a prandial glucose regulator that increases insulin release) plus metformin (an insulin sensitizer that inhibits hepatic glucose output, increases peripheral glucose uptake and utilization and minimizes weight gain). Findings from several clinical trials have shown that combination therapy with repaglinide plus metformin is well tolerated and results in greater reductions of haemoglobin A(1c) and fasting plasma glucose values compared with either monotherapy. Repaglinide may also provide a more suitable alternative to combination therapy with sulphonylureas and metformin because of its reduced propensity for hypoglycaemia. The combination regimen of repaglinide plus metformin should therefore be considered as a valuable option in the management of patients with type 2 diabetes when monotherapy is no longer adequate.

Cardiovascular outcomes in trials of oral diabetes medications: a systematic review

BACKGROUND

A wide variety of oral diabetes medications are currently available for the treatment of type 2 diabetes mellitus, but it is unclear how these agents compare with respect to long-term cardiovascular risk. Our objective was to systematically examine the peer-reviewed literature on the cardiovascular risk associated with oral agents (second-generation sulfonylureas, biguanides, thiazolidinediones, and meglitinides) for treating adults with type 2 diabetes.

METHODS

We searched MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials, from inception through January 19, 2006. Forty publications of controlled trials that reported information on cardiovascular events (primarily myocardial infarction and stroke) met our inclusion criteria. Using standardized protocols, 2 reviewers serially abstracted data from each article. Trials were first described qualitatively. For comparisons with 4 or more independent trials, results were pooled quantitatively using the Mantel-Haenszel method. Results are presented as odds ratios (ORs) and corresponding 95% confidence intervals (CIs).

RESULTS

Treatment with metformin hydrochloride was associated with a decreased risk of cardiovascular mortality (pooled OR, 0.74; 95% CI, 0.62-0.89) compared with any other oral diabetes agent or placebo; the results for cardiovascular morbidity and all-cause mortality were similar but not statistically significant. No other significant associations of oral diabetes agents with fatal or nonfatal cardiovascular disease or all-cause mortality were observed. When compared with any other agent or placebo, rosiglitazone was the only diabetes agent associated with an increased risk of cardiovascular morbidity or mortality, but this result was not statistically significant (OR, 1.68; 95% CI, 0.92-3.06).

CONCLUSIONS

Meta-analysis suggested that, compared with other oral diabetes agents and placebo, metformin was moderately protective and rosiglitazone possibly harmful, but lack of power prohibited firmer conclusions. Larger, long-term studies taken to hard end points and better reporting of cardiovascular events in short-term studies will be required to draw firm conclusions about major clinical benefits and risks related to oral diabetes agents.

Exploring the Pharmacotherapeutic Options for Treating Type 2 Diabetes

There has been a dramatic increase in the prevalence of the most common form of diabetes, with approximately 14.6 million diagnosed and 6.2 million undiagnosed cases of type 2 (non-insulin-dependent) diabetes in the United States since 2005. If diabetes is not diagnosed early and managed properly, patients are at greater risk for microvascular and macrovascular complications, such as nerve damage, heart disease, blindness, and kidney damage. The pathogenesis of type 2 diabetes includes impaired insulin secretion, increased hepatic and muscle/fat insulin resistance, and increased glucagon secretion. Problems commonly associated with type 2 diabetes and consequent hyperglycemia are weight gain, hypertension, and dyslipidemia. The natural progression of type 2 diabetes involves increased insulin deficiency as a result of decreased beta cell function over time, which can raise glycosylated hemoglobin to dangerous levels and consequently increase the risk of death. Lifestyle modifications (eg, diet changes and increased physical activity) remain the cornerstone of early treatment, but glycemic control may worsen despite behavior changes and treatment with oral hypoglycemic agents. Historically, upon failure to maintain glucose levels with exercise and oral medication, insulin was the second-line treatment option. Current treatment algorithms include a new class of agents, incretin mimetics, such as the glucagon-like peptide-1 (GLP-1) receptor agonist exenatide. Exenatide mimics the actions of the hormone GLP-1 that occurs naturally in the gastrointestinal tract and has emerged as an efficacious therapy adjunct to 1 or more oral hypoglycemic agent(s).

Defining the role of repaglinide in the management of type 2 diabetes mellitus: a review

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia due to a combination of insulin resistance and impaired insulin secretion. The hyperglycemia is associated with an increased risk for micro- and macrovascular complications, and lowering fasting and postprandial hyperglycemia may be protective against these complications. Repaglinide is an insulin secretagogue that lowers blood glucose levels in patients with T2DM. We review the effects of repaglinide in patients with T2DM, its impact on glycemia and its non-glycemic effects, and its effects when used in special situations or patient populations. Results from randomized controlled trials, observational studies, and safety reports involving humans and published in the English-language through 1 May 2007 identified by a search in PubMed/MEDLINE were evaluated. Present knowledge indicates that repaglinide reduces fasting and postprandial hyperglycemia and the level of glycosylated hemoglobin (HbA1c) in patients with T2DM. It is at least as effective in reducing HbA1c and fasting plasma glucose as sulphonylureas, metformin, or the glitazones and in combination therapy with other drugs, repaglinide is as effective as any other combination. Some studies show a better effect of repaglinide on postprandial glycemia than the comparators. Its propensity to induce hypoglycemia is similar to or a little less than that of sulphonylureas. Repaglinide is associated with less weight gain than sulphonylureas and the glitazones. Repaglinide has primarily a role in the treatment of T2DM when metformin cannot be used due to adverse effects, when metformin fails to adequately control blood glucose levels, when there is a need for flexible dosing (i.e. the elderly or during Ramadan fasting), or when there is a specific wish to lower postprandial glucose. Repaglinide may also have an advantage when an oral agent is needed in diabetic patients with renal impairment. Because of its short duration of action, repaglinide should be taken before each meal, usually at least three times a day. Although no study has investigated whether repaglinide lowers total mortality or cardiovascular endpoints, several studies indicate beneficial effects on cardiovascular surrogate endpoints, such as carotid intima-media thickening, markers of inflammation, platelet activation, lipid parameters, endothelial function, adiponectin, and oxidative stress. In conclusion, repaglinide is a compound that can be used in both mono- and combination therapy for the treatment of both fasting and postprandial hyperglycemia in patients with T2DM. It can be used in patients at different stages of the disease, from uncomplicated to severe renal impairment. Although the drug has been tested in a large number of clinical trials and observational studies, its world-wide use is far less than, for example, sulphonylureas. Repaglinide may offer an additional potential for lowering blood glucose levels in T2DM that until now has not been fully realized by many clinicians.

Postprandial dysmetabolism: the missing link between diabetes and cardiovascular events?

OBJECTIVE

To investigate the association of postprandial dysmetabolism, ie, hyperglycemia, and hyperlipidemia with myocardial disease in diabetic, glucose-intolerant, and glucose-tolerant patients.

METHODS

We performed a MEDLINE search of the English-language literature published between January 1979 and April 2007 for studies regarding postprandial dysmetabolism and heart disease.

RESULTS

Postprandial dysmetabolism is associated with increased inflammation, endothelial dysfunction, decreased fibrinolysis, plaque instability, and cardiac events.

CONCLUSION

There is a direct and proportional association between postprandial dysmetabolism and both coronary artery disease and cardiac events.

Type 2 diabetes mellitus: epidemiology, pathophysiology, unmet needs and therapeutical perspectives

In France, prevalence of drug-treated diabetes reached 3.60% in 2005, with 92% of type 2 diabetic patients. In 2007, there are probably nearly 3000 000 diagnosed or undiagnosed diabetic patients. Ageing of the population and increase in obesity are the main causes of this "diabetes epidemic". Type 2 diabetes is a multifactorial disease, defined as resulting from defects in insulin secretion (including abnormalities in pulsatility and kinetics, quantitative and qualitative abnormalities of insulin, beta-cell loss progressing with time) associated with insulin resistance (affecting liver, and skeletal muscle) and increased glucagon secretion. The lack of compensation of insulin resistance by augmented insulin secretion results in rise in blood glucose. To achieve satisfactory glycaemic control in order to prevent diabetes related complications, drug therapy is generally required in addition to life style changes. Currently available oral therapies offer a large panel of complementary drugs, but they have several contraindications and side effects. In spite of major advances in the management of type 2 diabetes, and the strictness of new guidelines, some goals remain unachieved and the new family of insulin-secretors (DPP-IV inhibitors, GLP-1 analogues) should enrich therapeutic approaches.

A systematic review and meta-analysis of hypoglycemia and cardiovascular events: a comparison of glyburide with other secretagogues and with insulin

OBJECTIVE

Glyburide is the most widely used sulfonylurea but has unique pharmacodynamic properties that may increase harm. We hypothesized that glyburide causes more hypoglycemia and cardiovascular events than other secretagogues or insulin.

RESEARCH DESIGN AND METHODS

Data sources were Medline, Embase, Cochrane, and three other web-based clinical trial registers (1966-2005). Parallel, randomized, controlled trials in people with type 2 diabetes comparing glyburide monotherapy with monotherapy using secretagogues or insulin were selected. Outcomes were hypoglycemia, glycemic control, cardiovascular events, body weight, and death. Titles and abstracts of 1,806 publications were reviewed in duplicate and 21 relevant articles identified. Data on patient characteristics, interventions, outcomes, and validity were extracted in duplicate using predefined criteria.

RESULTS

Glyburide was associated with a 52% greater risk of experiencing at least one episode of hypoglycemia compared with other secretagogues (relative risk 1.52 [95% CI 1.21-1.92]) and with 83% greater risk compared with other sulfonylureas (1.83 [1.35-2.49]). Glyburide was not associated with an increased risk of cardiovascular events (0.84 [0.56-1.26]), death (0.87 [0.70-1.07]), or end-of-trial weight (weighted mean difference 1.69 kg [95% CI -0.41 to 3.80]) compared with other secretagogues. Limitations included suboptimal reporting of original trials. Loss to follow-up exceeded 20% in some studies, and major hypoglycemia was infrequently reported.

CONCLUSIONS

Glyburide caused more hypoglycemia than other secretagogues and other sulfonylureas. Glyburide was not associated with an increased risk of cardiovascular events, death, or weight gain.

Targeting postprandial hyperglycemia

In healthy individuals, blood glucose levels in the fasting state are maintained by the continuous basal-level insulin secretion. After a meal, the rise in postprandial glucose (PPG) is controlled by the rapid pancreatic release of insulin, stimulated by both glucose and the intestinal production of the incretins glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1. In diabetic individuals, postprandial insulin secretion is insufficient to suppress an excessive rise in PPG. There is increasing evidence that elevated PPG exerts a more deleterious effect on the vascular system than elevation of fasting plasma glucose. In particular, individuals with normal fasting plasma glucose but impaired glucose tolerance have significantly increased risk of cardiovascular events. With the recognition of the importance of PPG and the availability of new pharmacologic options, management of diabetes will shift to greater attention to PPG levels. The prototype for such an approach is in the treatment of gestational diabetes and diabetic pregnancies where PPG is the primary target of efforts at glycemic control. These efforts have been extremely successful in improving the outlook for diabetic pregnant women. There are many approaches to reduction of PPG; dietary management and promotion of exercise are very effective. Sulfonylureas, meglitinides, metformin, thiazolidinediones, and disaccharidase inhibitors all counteract PPG elevation. The development of glucagon-like peptide 1 agonists such as exendin and dipeptidyl peptidase IV inhibitors such as vildagliptin offers a new approach to suppression of PPG elevation. New semisynthetic insulin analogues permit a more aggressive response to postprandial glucose elevation, with lower risk of hypoglycemia, than with regular insulin. Inhaled insulin also has a rapid onset of action and offers benefits in PPG control. It is proposed that an aggressive treatment approach focusing on PPG, similar to the current standards for diabetic pregancies, be directed at individuals with diabetes and impaired glucose tolerance.

Meglitinide analogues: a review of clinical data focused on recent trials

Glinides represent a chemically heterogeneous new class of insulin-secreting agents characterized by a rapid onset and short duration of action. They act by closure of the ATP-dependant K channel. Repaglinide, the only glinide available in France, has an equivalent HbA1c lowering effect to conventional sulfonylureas but reduces predominantly postprandial glucose levels. Several studies indicate a decreased risk of hypoglycaemias, particularly nocturnal or in case of a shift or omission of a meal. This drug appears particularly useful in early stage type 2 diabetes or in combination with metformin. The only significant drug-drug interaction concerns gemfibrozil. Due to its hepatic metabolism and biliary elimination, repaglinide can be used in patients with renal insufficiency. Nateglinide has a even shorter duration of action and has almost no effect on fasting plasma glucose levels. For this reason, this drug is only indicated in combination with metformin in the countries where it is licensed. Several experimental data suggest that glinides could preserve B cell function over time better than hypoglycaemic sulfonylureas, and that the improvement of post-prandial glucose levels could exert a long term protective cardiovascular effect.

Prevalence and correlates of post-prandial hyperglycaemia in a large sample of patients with type 2 diabetes mellitus

AIMS/HYPOTHESIS

Post-prandial glucose may be a risk factor for cardiovascular disease and chronic diabetic complications. We tested the hypothesis that post-prandial hyperglycaemia is common in type 2 diabetes, even among patients in apparently good glycaemic control, and that simple clinical characteristics identify subsets of diabetic patients with frequent post-prandial hyperglycaemia.

SUBJECTS AND METHODS

Three self-assessed daily blood glucose profiles over a 1-week period, including 18 glucose readings before and 2 h after meals, were obtained from 3,284 unselected outpatients (men 51%; age 63+/-10 years) with non-insulin-treated type 2 diabetes mellitus attending 500 different diabetes clinics operating throughout Italy.

RESULTS

A post-prandial blood glucose value >8.89 mmol/l (160 mg/dl) was recorded at least once in 84% of patients, and 81% of patients had at least one Delta glucose > or =2.22 mmol/l (40 mg/dl). Among patients with apparently good metabolic control, 38% had >40% of post-prandial blood glucose readings >8.89 mmol/l (> or =4 of 9 meals in total), and 36% had >40% Delta glucose > or =2.22 mmol/l. In multivariate analysis adjusted for pre-prandial glucose levels, older age, longer duration of diabetes, absence of obesity, hyperlipidaemia and hypertension, as well as treatment with sulfonylureas, were significantly associated with greater glucose excursions after meals.

CONCLUSIONS/INTERPRETATION

These results indicate that post-prandial hyperglycaemia is a very frequent phenomenon in patients with type 2 diabetes mellitus on active treatment; can occur even when metabolic control is apparently good; and can be predicted by simple clinical features.

Exenatide improves glycemic control and reduces body weight in subjects with type 2 diabetes: a dose-ranging study

BACKGROUND

Exenatide is the first of a new class of agents known as incretin mimetics that are in development for the treatment of type 2 diabetes. Exenatide has been shown to reduce fasting and postprandial glucose in patients with type 2 diabetes, as well as provide sustained reductions in hemoglobin A 1c (HbA 1c). This study was designed to assess the dose dependencies of the glucoregulatory effects and tolerability of exenatide when added to diet and exercise or metformin monotherapy in patients with type 2 diabetes.

METHODS

In this randomized, triple-blinded, placebo-controlled Phase 2 clinical trial, 156 patients were randomized to placebo or exenatide at 2.5, 5.0, 7.5, or 10.0 microg administered b.i.d. for 28 days.

RESULTS

After 28 days of therapy, exenatide was associated with significant (P < 0.0001, linear contrast testing), dose-dependent reductions in HbA 1c (0.1 +/- 0.1%, -0.3 +/- 0.1%, -0.4 +/- 0.1%, +/-0.5 +/- 0.0%, and -0.5 +/- 0.1% for placebo and 2.5, 5.0, 7.5, and 10.0 microg b.i.d. exenatide, respectively) and significant (P = 0.0006, linear contrast testing) reductions in fasting plasma glucose (+6.8 +/- 4.1, -20.1 +/- 5.2, -21.2 +/- 3.9, -17.7 +/- 4.8, and -17.3 +/- 4.4 mg/dL for placebo and 2.5, 5.0, 7.5, and 10.0 microg b.i.d. exenatide, respectively) by Day 28. These reductions were similar for patients treated with diet/exercise and those treated with metformin. In addition, patients receiving exenatide exhibited dose-dependent reductions in body weight (0.0 +/- 0.3, -0.7 +/- 0.3, -0.7 +/- 0.2, -1.4 +/- 0.3, and -1.8 +/- 0.3 kg for placebo and 2.5, 5.0, 7.5, and 10.0 microg b.i.d. exenatide, respectively; P < 0.01 for 7.5 and 10.0 microg b.i.d. exenatide doses compared with placebo) at Day 28. The most common adverse event was mild-to-moderate nausea that was dose-dependent (seven of 123 patients randomized to exenatide withdrew from the study because of gastrointestinal effects).

CONCLUSIONS

Exenatide dose-dependently improved glycemic control and reduced body weight over 28 days in patients with type 2 diabetes treated with diet/exercise or metformin.

Role of insulin secretagogues and insulin sensitizing agents in the prevention of cardiovascular disease in patients who have diabetes

In the absence of clinical trial evidence to compare the secretagogues with sensitizers, it is difficult to make recommendations about which class of drug is more important to prescribe for the prevention of cardiovascular disease in diabetes mellitus. Epidemiologic data supports insulin resistance as a major factor in cardiovascular disease through a variety of mechanisms. Because sensitizers improve insulin sensitivity and correct many of the vascular abnormalities that are associated with insulin resistance, it is tempting to suggest that they may be superior for this purpose. Conversely, meeting the goals that are recommended for glycemia also are important and achieving them may not be always possible with sensitizers, particularly in the later stages of the disease when insulin levels are not high,despite insulin resistance. In such situations,combination therapy may be needed with both types of drugs. No data are available on the cardiovascular effects of such combinations;some retrospective data suggest a possibility of increased events with the combination of sulfonylureas and metformin. Thus, further prospective studies in this area are necessary.

Compared to glibenclamide, repaglinide treatment results in a more rapid fall in glucose level and beta-cell secretion after glucose stimulation

BACKGROUND

The more rapid onset of action and the shorter half-life of repaglinide may reduce the post-load glucose excursion and limit sustained insulin secretion compared to sulphonylurea (SU) derivatives.

METHODS

We studied 12 patients with type 2 diabetes (age 62 +/- 2 years, BMI 28.3 +/- 1.3 kg m(-2), HbA1c 6.7 +/- 0.2%) on SU monotherapy at submaximal dose. Patients were treated for 3 weeks with repaglinide or glibenclamide in a randomized, crossover trial. At the end of each treatment period, patients underwent a 60-min hyperglycaemic clamp (glucose 12 mmol L(-1)) followed by 4-h observation (60-300 min) with frequent blood sampling for determination of glucose, insulin, proinsulin and C-peptide levels. Before the clamp (5 min for repaglinide, 30 min for glibenclamide), patients ingested their usual morning drug dose.

RESULTS

After the end of the hyperglycaemic clamp, mean plasma glucose fell to a level of 5 mmol L(-1) after approximately 150 min with repaglinide, and after approximately 190 min with glibenclamide. While initially quite similar, in the period from 240 to 300 min, insulin, proinsulin and C-peptide levels were lower during repaglinide treatment (insulin 133 +/- 20 vs 153 +/- 25 pmol L(-1) (P < 0.05), proinsulin 14 +/- 3 vs 19 +/- 4 pmol L(-1) (P = 0.06) and C-peptide 0.81 +/- 0.19 vs 1.14 +/- 0.18 nmol L(-1) (P = 0.05) for repaglinide vs glibenclamide, respectively).

CONCLUSIONS

Following glucose stimulation, plasma glucose levels, and insulin concentration decrease more rapidly after repaglinide treatment than after glibenclamide. Proinsulin and C-peptide secretion tended to fall more rapidly as well. These findings are consistent with a more rapid onset and shorter duration of beta-cell stimulation associated with repaglinide.

The role of sulphonylureas in the management of type 2 diabetes mellitus

The sulphonylureas act by triggering insulin release from the pancreatic beta cell. A specific site on the adenosine triphosphate (ATP)-sensitive potassium channels is occupied by sulphonylureas leading to closure of the potassium channels and subsequent opening of calcium channels. This results in exocytosis of insulin. The meglitinides are not sulphonylureas but also occupy the sulphonylurea receptor unit coupled to the ATP-sensitive potassium channel. Glibenclamide (glyburide), gliclazide, glipizide and glimepiride are the primary sulphonylureas in current clinical use for type 2 diabetes mellitus. Glibenclamide has a higher frequency of hypoglycaemia than the other agents. With long-term use, there is a progressive decrease in the effectiveness of sulphonylureas. This loss of effect is the result of a reduction in insulin-producing capacity by the pancreatic beta cell and is also seen with other antihyperglycaemic agents. The major adverse effect of sulphonylureas is hypoglycaemia. There is a theoretical concern that sulphonylureas may affect cardiac potassium channels resulting in a diminished response to ischaemia. There are now many choices for initial therapy of type 2 diabetes in addition to sulphonylureas. Metformin and thiazolidinediones affect insulin sensitivity by independent mechanisms. Disaccharidase inhibitors reduce rapid carbohydrate absorption. No single agent appears capable of achieving target glucose levels in the majority of patients with type 2 diabetes. Combinations of agents are successful in lowering glycosylated haemoglobin levels more than with a single agent. Sulphonylureas are particularly beneficial when combined with agents such as metformin that decrease insulin resistance. Sulphonylureas can also be given with a basal insulin injection to provide enhanced endogenous insulin secretion after meals. Sulphonylureas will continue to be used both primarily and as part of combined therapy for most patients with type 2 diabetes.

[Future targets in the treatment of type 2 diabetes]

Prevention and treatment of type 2 diabetes mellitus (T2DM) and the metabolic syndrome represent a major clinical challenge, because effective strategies such as fat restriction and exercise are difficult to implement into diabetes treatment. Based on the increasing knowledge on the pathogenesis of T2DM, new therapeutic approaches are currently under investigation. Potential targets of new therapeutic approaches include: (i) Inhibition of hepatic glucose production, (ii) stimulation of glucose-dependent insulin secretion, (iii) enhancement of insulin signal transduction, and (iv) reduction of body fat mass. Agonists of glucagon-like-peptide 1 (GLP-1) and antagonists of dipeptidylpeptidase IV, which inactivates GLP-1, stimulate glucose-dependent insulin secretion, improve hyperglycemia and are already tested in clinical trials. In humans, glucagon antagonists and an amylin analogue reduce glucagon-dependent glucose production. The glucose-lowering effect of current modulators of lipid oxidation is not pronounced and their use could be limited by side effects. In addition to clinically approved thiazolidendiones, new agonists of the peroxisome proliferator activator receptor gamma (PPAR gamma) as well as combined PPAR alpha/gamma agonists are developed at present. The direct modulation of insulin signal transduction is still limited to experimental studies.

Regression of carotid atherosclerosis by control of postprandial hyperglycemia in type 2 diabetes mellitus

BACKGROUND

Postprandial hyperglycemia may be a risk factor for cardiovascular disease. We compared the effects of two insulin secretagogues, repaglinide and glyburide, known to have different efficacy on postprandial hyperglycemia, on carotid intima-media thickness (CIMT) and markers of systemic vascular inflammation in type 2 diabetic patients.

METHODS AND RESULTS

We performed a randomized, single-blind trial on 175 drug-naive patients with type 2 diabetes mellitus (93 men and 82 women), 35 to 70 years of age, selected from a population of 401 patients who participated in an epidemiological analysis assessing the relation of postprandial hyperglycemia to surrogate measures of atherosclerosis. Eighty-eight patients were randomly assigned to receive repaglinide and 87 patients to glyburide, with a titration period of 6 to 8 weeks for optimization of drug dosage and a subsequent 12-month treatment period. The effects of repaglinide (1.5 to 12 mg/d) and glyburide (5 to 20 mg/d) on CIMT were compared by using blinded, serial assessments of the far wall. After 12 months, postprandial glucose peak was 148+/-28 mg/dL in the repaglinide group and 180+/-32 mg/dL in the glyburide group (P<0.01). HbA(1c) showed a similar decrease in both groups (-0.9%). CIMT regression, defined as a decrease of >0.020 mm, was observed in 52% of diabetics receiving repaglinide and in 18% of those receiving glyburide (P<0.01). Interleukin-6 (P=0.04) and C-reactive protein (P=0.02) decreased more in the repaglinide group than in the glyburide group. The reduction in CIMT was associated with changes in postprandial but not fasting hyperglycemia.

CONCLUSIONS

Reduction of postprandial hyperglycemia in type 2 diabetic patients is associated with CIMT regression.

Are hypoglycaemia and other adverse effects similar among sulphonylureas?

This review provides an updated overview of the adverse effects of sulphonylureas and identifies factors associated with variation in adverse effect rates among sulphonylureas published by different studies. A search of Medline, Embase, Current Contents and Cochrane Library was conducted to identify all papers related to sulphonylureas and adverse effects published from 1950-2001. The reference lists of all relevant papers were also searched for additional articles. The frequency of sulphonylurea-induced hypoglycaemia varied from 1.8-59%. Severe hypoglycaemia due to sulphonylurea use has been reported from 1.9-3.5%. Variation in hypoglycaemia rates may be due to differences in definitions, methods to detect and to collect information, patient characteristics, patient knowledge of the condition, threshold for symptoms, and activity level during hypoglycaemia. Other adverse effects associated with sulphonylurea use include bodyweight gain, gastrointestinal distress, disulphiram-like syndrome, dermatological reactions, haematological changes, ocular problems, and the syndrome of inappropriate secretion of antidiuretic hormone. Bodyweight gain has been reported to vary from 1.7-4.8 kg, according to the United Kingdom Prospective Diabetes Study (UKPDS-33). Controversy exists regarding cardiovascular adverse effects, but the consensus is to exercise caution in the use of these drugs as first-line therapy for patients with diabetes mellitus and coronary artery disease. The benefits of sulphonylurea treatment should be weighed against the risks associated with them. More work in this area is needed to homogenise the definition of hypoglycaemia, to get consensus on the methods for detection and data collection, as well as to further patient and physician education.

Comparison between repaglinide and glimepiride in patients with type 2 diabetes mellitus: a one-year, randomized, double-blind assessment of metabolic parameters and cardiovascular risk factors

BACKGROUND

Repaglinide and glimepiride are relatively new oral hypoglycemic agents. Few data are available concerning their effects on metabolic parameters other than measures of glycemic control.

OBJECTIVES

In addition to assessing the effects of repaglinide and glimepiride on glycemic control in patients with type 2 diabetes mellitus, this study also examined the effects of these agents on 3 metabolic parameters known to be cardiovascular risk factors--lipoprotein(a) (Lp[a]), plasminogen activator inhibitor-1 (PAI-1), and homocysteine (Hcy).

METHODS

This randomized, placebo-controlled, double-blind trial was conducted at a single center in Italy. Eligible patients were nonsmokers; had no hypertension or coronary heart disease; were taking no hypolipidemic drugs, diuretics, beta-blockers, or thyroxin; and had normal renal function. After an initial 4-week placebo washout period, patients were randomized to receive repaglinide 1 mg/d or glimepiride 1 mg/d. The dose of study drug was optimized over an 8-week titration period, which was followed by a 12-month treatment period. Measures of glycemic control (glycated hemoglobin [HbA1c], fasting plasma glucose [FPG], postprandial plasma glucose [PPG], fasting plasma insulin [FPI], postprandial plasma insulin [PPI]) and the other metabolic parameters of interest were assessed after 6 and 12 months of treatment.

RESULTS

One hundred twenty-four patients (63 women, 61 men) completed the study, 62 in each treatment group. There were no significant differences in demographic characteristics between groups. After 6 and 12 months of treatment, FPG levels and HbA1c values were significantly reduced from baseline in both groups (6 months, P < 0.05; 12 months, P < 0.01). After 6 months, PPG levels were significantly decreased only in the repaglinide group (P < 0.05 vs baseline); at 12 months, however, PPG levels were significantly reduced from baseline in both groups (P < 0.01 repaglinide, P < 0.05 glimepiride). No significant changes from baseline in FPI or PPI levels were seen in either group at 6 months, although FPI levels were significantly increased in the repaglinide group at 12 months (P < 0.05). Repaglinide significantly lowered levels of Lp(a), PAI-1, and Hcy after 12 months (all, P < 0.05 vs baseline). Glimepiride significantly lowered levels of Lp(a) and Hcy after 6 months (both, P < 0.05 vs baseline) and levels of Lp(a) (P < 0.01 vs baseline), Hcy (P < 0.01 vs baseline), and PAI-1 (P < 0.05 vs baseline) after 12 months.

CONCLUSIONS

Repaglinide and glimepiride improved glycemic control and reduced levels of other metabolic parameters of interest in this population of patients with type 2 diabetes. It is possible that the reductions in Lp(a), PAI-1, and Hcy were the result of improved glucose metabolism; however, the possibility that repaglinide and glimepiride may have a direct effect on these parameters should not be excluded.

Population PKPD modelling of the long-term hypoglycaemic effect of gliclazide given as a once-a-day modified release (MR) formulation

AIMS

To study the relationship between the pharmacokinetics (PK) of gliclazide and its long-term pharmacodynamic (PD) effect in a large population of Type 2 diabetic patients and to identify factors predicting intersubject variability.

METHODS

A PKPD database of 634 Type 2 diabetic patients with a total of 5,258 fasting plasma glucose (FPG) samples was built up from the data collected during the clinical development of a modified release formulation of gliclazide (gliclazide MR). The PKPD analysis used a nonlinear mixed effect modelling approach. A mixture model was used to identify patients with a FPG response to treatment. In patients identified as responders, the decrease in FPG was related to gliclazide exposure (AUC) by an Emax relationship. An effect compartment was used to describe the link between PK and PD. A linear disease-progression model was used to assess the glycaemic deterioration observable over several months of treatment. Simulations were performed to evaluate the predictive performance of the PKPD model and to illustrate the time course of the antidiabetic effect of gliclazide MR.

RESULTS

Disease state was found to be the main explanatory factor for intersubject variability in response to gliclazide. The percentage of responders to gliclazide, used as monotherapy, increased inversely to the number of classes of antidiabetic agents received prior to entry in the studies. In responders, the initial dose (30 mg) of the gliclazide MR dosing regimen induced half of the maximum hypoglycaemic effect. The equilibration half-life between the PK and PD steady states was 3 weeks (intersubject variability of 84%). The rate of disease progression was 0.84 mmol l(-1) year(-1) (intersubject variability 143%). The PKPD model adequately predicted the FPG profiles of 234 patients who received the current formulation of gliclazide. Simulation of a 1-year parallel dose ranging clinical trial illustrated the influence of dose, time and type of previous antidiabetic treatment on the percentage of patients with clinically significant improvement of blood glucose control.

CONCLUSIONS

This population PKPD analysis has characterized the relationship between the exposure to gliclazide and its long-term hypoglycaemic effect, and has established that the intersubject variability in response is mostly related to disease state. These results underline the clinical interest of quickly increasing the dose of gliclazide MR according to the response to treatment in order to achieve effective blood glucose control.

The effect of repaglinide on insulin secretion and oxidative stress in type 2 diabetic patients

The effect of repaglinide on insulin secretion and oxidative stress was evaluated in type 2 diabetic patients in a randomized, controlled, open-label trial. Forty-six patients were treated for 2 months with repaglinide, added to either diet (n=21) or metformin (n=25). A control group of 29 patients, matched for age, weight and glycaemic control, on either diet (n=13) or metformin (n=16) was also followed-up. Phases of insulin secretion (first-FPIS and second-SPIS) ware studied during IVGTT. Total serum antioxidant capacity and serum superoxide dismutase (SOD) activity were measured to assess oxidative stress. HbA(1c) decreased significantly in the repaglinide-treated group (P=0.01), the difference being significant compared with the control group (P=0.01). FPIS increased significantly after repaglinide (P<0.001). The area under the curve (AUC) for FPIS increased significantly (P<0.001), while the AUC for SPIS and for total insulin secretion did not change. Insulin secretion remained unchanged after 2 months in the control group. There was a significant increase after repaglinide in total serum antioxidant capacity (P<0.05) and serum SOD activity (P<0.0004); the difference compared to the control group being significant (P<0.002). Our results demonstrate the physiological effect of repaglinide on endogenous insulin secretion in a controlled, randomized, open-label study-there is a rise only in FPIS, which is the main beta-cell defect in type 2 diabetes mellitus. This improvement in glycaemic control was accompanied by a beneficial effect on oxidative stress in diabetes mellitus.

Repaglinide versus glibenclamide treatment of Type 2 diabetes during Ramadan fasting

This study compared treatment with a prandial glucose regulator (repaglinide) and a sulphonylurea (glibenclamide) in Muslim Type 2 diabetic patients who practice Ramadan fasting. Two hundred and thirty-five patients, previously treated with a sulphonylurea, were randomised to receive either repaglinide (n=116, preprandially three-times daily) or glibenclamide (n=119, preprandially once- or twice-daily) 6 weeks before Ramadan. During Ramadan, patients changed their eating pattern to two meals daily, and the daily dose of repaglinide was redistributed to two preprandial doses. After Ramadan, patients resumed their regular meal pattern and treatment dosage for 4 weeks. During Ramadan, a statistically significant reduction in mean serum fructosamine concentration from baseline was observed in the repaglinide group (-16.9+/-4.9 micromol/l, -3.8%, P<0.05) but not the glibenclamide group (-6.9+/-4.8 micromol/l, -0.8%). Difference in change in HbA(1c) from baseline was not statistically significant between groups. The number of hypoglycaemic events with midday blood glucose <4.5 mmol/l was significantly lower in the repaglinide group (2.8%) than the glibenclamide group (7.9%) (P=0.001). Apart from hypoglycaemia, both treatments were equally well tolerated. Type 2 diabetic Muslims using prandial repaglinide showed a trend towards better glycaemic control and had a lower frequency of hypoglycaemia than patients using glibenclamide during Ramadan.

Type 2 diabetes management: a comprehensive clinical review of oral medications

Diabetes is a major and growing health problem in the US. An incredible array of different oral medications is now on the market. Clinicians should understand all these new medications and in which clinical picture they will work best.

Repaglinide: a review of its therapeutic use in type 2 diabetes mellitus

Repaglinide, a carbamoylmethyl benzoic acid derivative, is the first of a new class of oral antidiabetic agents designed to normalise postprandial glucose excursions in patients with type 2 diabetes mellitus. Like the sulphonylureas, repaglinide reduces blood glucose by stimulating insulin release from pancreatic beta-cells, but differs from these and other antidiabetic agents in its structure, binding profile, duration of action and mode of excretion. In clinical trials of up to 1-year's duration, repaglinide maintained or improved glycaemic control in patients with type 2 diabetes mellitus. In comparative, 1-year, double-blind, randomised trials (n = 256 to 544), patients receiving repaglinide (0.5 to 4mg before 3 daily meals) achieved similar glycaemic control to that in patients receiving glibenclamide (glyburide) < or = 15 mg/day and greater control than patients receiving glipizide < or = 15 mg/day. Changes from baseline in glycosylated haemoglobin and fasting blood glucose levels were similar between patients receiving repaglinide and glibenclamide in all studies; however, repaglinide was slightly better than glibenclamide in reducing postprandial blood glucose in I short term study (n = 192). Patients can vary their meal timetable with repaglinide: the glucose-lowering efficacy of repaglinide was similar for patients consuming 2, 3 or 4 meals a day. Repaglinide showed additive effects when used in combination with other oral antidiabetic agents including metformin, troglitazone, rosiglitazone and pioglitazone, and intermediate-acting insulin (NPH) given at bedtime. In 1-year trials, the most common adverse events reported in repaglinide recipients (n = 1,228) were hypoglycaemia (16%), upper respiratory tract infection (10%), rhinitis (7%), bronchitis (6%) and headache (9%). The overall incidence of hypoglycaemia was similar to that recorded in patients receiving glibenclamide, glipizide or gliclazide (n = 597) [18%]; however, the incidence of serious hypoglycaemia appears to be slightly higher in sulphonylurea recipients. Unlike glibenclamide, the risk of hypoglycaemia in patients receiving repaglinide was not increased when a meal was missed in 1 trial. In conclusion, repaglinide is a useful addition to the other currently available treatments for type 2 diabetes mellitus. Preprandial repaglinide has displayed antihyperglycaemic efficacy at least equal to that of various sulphonylureas and is associated with a reduced risk of serious hypoglycaemia. It is well tolerated in a wide range of patients, including the elderly, even if a meal is missed. Furthermore, glycaemic control is improved when repaglinide is used in combination with metformin. Thus, repaglinide should be considered for use in any patient with type 2 diabetes mellitus whose blood glucose cannot be controlled by diet or exercise alone, or as an adjunct in patients whose glucose levels are inadequately controlled on metformin alone.

Insulin secretagogues

Existing oral insulin secretagogues, sulphonylureas, are associated with hyperinsulinaemia, risk of hypoglycaemia and weight gain. Furthermore, they are not able to offer durable glycaemic control in patents with type 2 diabetes and are associated with progressive decline of beta-cell function. New insulin secretagogues offer an exciting opportunity. Repaglinide, the first prandial glucose regulator, now has convincing data that, compared to sulphonylurea use, it has a lower risk of hypoglycaemia. When used in a flexible dosing regime in a large cohort of patients, it is associated with better glycaemic control, a reduction in HbA1c, weight loss and improved quality of life compared to sulphonylureas. Early data shows the possibility of an effective combination with night time isophane insulin with significant falls in HbA1c and lower doses of insulin required. Nateglinide is an amino acid derivative. It again acts directly on the pancreatic beta-cell. Because of its very short duration of action, and the fact that it appears to secrete insulin in a glucose-dependent manner, it appears to secrete insulin in the closest way to that seen in a person without diabetes. Early data, both in monotherapy and in combination with metformin, show that it is an effective agent in terms of lowering HbA1c, has a low risk of hypoglycaemia and potentially less risk of significant weight gain. These characteristics mean that it may be the ideal agent to be used very early in the disease process, or even in subjects with impaired glucose tolerance, in whom early-phase insulin response is already lost. However these concepts, at the present time, are unproven.

Postprandial Hyperglycemia in Patients with Type 2 Diabetes Mellitus

The role of postprandial hyperglycemia (PPHG) in diabetes mellitus is being increasingly recognized. It is known that PPHG contributes to the increased risk of both micro- and macrovascular complications in patients with diabetes mellitus. This review looks at the clinical significance of PPHG and the currently available therapeutic modalities. The causes of PPHG are influenced by many factors which include a rapid flux of glucose from the gut, impaired insulin release, endogenous glucose production by the liver and peripheral insulin resistance. Knowledge of the pathophysiology of PPHG is essential when adopting treatment options to tackle the problem. Although most oral antihyperglycemic agents and insulins lower both fasting and postprandial blood glucose levels, drugs are now available which specifically act to control PPHG. These drugs may be classified based on the site of their action. alpha-Glucosidase inhibitors like acarbose and miglitol attenuate the rate of absorption of sucrose by acting on the luminal enzymes. Adverse effects of these agents are predominantly gastrointestinal. Newer insulin secretagogues have been developed which attempt to mimic the physiological release of insulin and thus ameliorate PPHG. These include third generation sulfonylureas like glimepiride and nonsulfonylurea secretagogues like repaglinide and nateglinide. Rapid-acting insulin analogs, the amino acid sequences of which have been altered such that they have a faster onset of action, help to specifically target PPHG. Pre-mixed formulations of the analogs have also been developed. Finally, drugs under development which hold promise in the management of patients with PPHG include pramlintide, an amylin analog, and glucagon-like peptide-1 and its analogs.

Plasma glucose levels throughout the day and HbA(1c) interrelationships in type 2 diabetes: implications for treatment and monitoring of metabolic control

OBJECTIVE

To evaluate the extent of plasma glucose excursions with meals, the relations between plasma glucose levels at different times of the day, and the relations between the latter and HbA(1c) in non-insulin-treated type 2 diabetic subjects.

RESEARCH DESIGN AND METHODS

Daily glucose profiles were assessed in non-insulin-treated type 2 diabetic patients. Outpatients at the diabetes clinic (n = 371; one daily plasma glucose profile) and at home (n = 30; five daily blood glucose profiles over 1 month) as well as inpatients (n = 455; profile of plasma glucose on the day of admission) were examined. Subjects had plasma/blood glucose assessment before and 2-3 h after breakfast, lunch, and dinner. HbA(1c) was also measured.

RESULTS

After the meals many subjects had glucose levels >8.9 mmol/l (160 mg/dl) and/or glucose excursions >2.2 mmol/l (40 mg/dl). This was also often found when HbA(1c) was satisfactory (<7%). The coefficients of simple correlation among plasma/blood glucose at different times of the day ranged from 0.52 to 0.88. Correlations between HbA(1c) and plasma/blood glucose at different times of the day ranged from 0.44 to 0.67. The strongest correlation was between HbA(1c) and mean daily glucose (r = 0.57-0.69). Multiple regression analyses showed that premeal but not postmeal plasma/blood glucose levels were independent predictors of HbA(1c).

CONCLUSIONS

These results suggest that 1) the majority of non-insulin-treated type 2 diabetic patients have exaggerated plasma/blood glucose excursions with meals, and many of them have higher-than-recommended glucose concentrations 2 h after the meals; 2) plasma/blood glucose levels throughout the day are not as strongly interrelated as one might believe; and 3) HbA(1c) is more related to preprandial than postprandial plasma/blood glucose levels. These findings have potential implications for treatment and monitoring of metabolic control in type 2 diabetes.

Comparison between repaglinide and glipizide in Type 2 diabetes mellitus: a 1-year multicentre study

AIMS

To evaluate the long-term effectiveness and safety of repaglinide, a novel prandial glucose regulator, in comparison with glipizide in the treatment of patients with Type 2 diabetes.

METHODS

Diet or tablet-treated patients with Type 2 diabetes (n = 256; age 40-75 years, body mass index (BMI) 20-35 kg/m2, HbA1c 4.2-12.8%), without signs of severe microvascular or macrovascular complications, were included in this double-blind, multicentre, parallel-group comparative trial. Patients were randomized at a 2:1 ratio to repaglinide, 1-4 mg at mealtimes, or glipizide, 5-15 mg daily.

RESULTS

Changes in fasting blood glucose (FBG) and HbA1c during the 12 months of treatment showed a significant difference in favour of repaglinide. In oral hypoglycaemic agents (OHA)-naive patients, HbA1c decreased in the repaglinide and glipizide groups by 1.5% and 0.3%, respectively (P < 0.05 between groups). Fasting blood glucose decreased in the repaglinide group by 2.4 mmol/l and increased in the glipizide group by 1.0 mmol/l (P < 0.05 between groups). In the study population as a whole, repaglinide was able to maintain glycaemic control (HbA1c level) during the 1-year study period, whereas control deteriorated significantly with glipizide. Change in HbA1c from baseline was significantly better with repaglinide than with glipizide after 12 months (P < 0.05). In addition, FBG deteriorated significantly in the glipizide group compared with the repaglinide group (P < 0.05). No patients in either group experienced a major hypoglycaemic event; the number of patients experiencing minor hypoglycaemia was similar in the repaglinide and glipizide groups (15% and 19%, respectively).

CONCLUSIONS

Repaglinide, given as a prandial glucose regulator, is shown to be an effective and safe treatment of patients with Type 2 diabetes, and is better than glipizide in controlling HbA1c and FBG levels, overall, and in OHA-naive patients.