Nateglinide alone and in combination with metformin improves glycemic control by reducing mealtime glucose levels in type 2 diabetes

Efficacy and Safety of DPP-4 Inhibitors and Metformin Combinations in Type 2 Diabetes: A Systematic Literature Review and Network Meta-Analysis

Objective

Several oral antidiabetic regimens are available for treating type 2 diabetes mellitus (T2DM), dipeptidyl peptidase-4 inhibitors (DPP4i) being one of them. We conducted a network meta-analysis (NMA) comparing DPP4i plus metformin (Met) combination with other Met-based oral antidiabetic drug (OAD) combinations used in treating patients with T2DM.

Methods

We searched PubMed and Embase from inception until 19th April, 2022 for phase II and phase III trials in patients with T2DM on Met-based traditional OADs. The primary outcome was assessed by change in glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), and 2-hour post-prandial blood glucose (2h-PPG). The secondary safety outcomes assessed were hypoglycemic events, serious adverse events (SAEs), cardiovascular (CV) events, and gastrointestinal (GI) events.

Results

Sixty-two trials were included in the analysis. The combination of DPP4i + Met revealed a comparable mean reduction in HbA1c levels to the glinides (Gli) + Met combination (mean difference [MD]: -0.03%, 95% CI: 0.69, -0.65), although the difference was not statistically significant. The mean HbA1c reduction with DPP4i + Met was greater than with sulfonylureas (SU) + Met (MD: -0.05, 95% CI: -0.29, 0.39), thiazolidinedione (TZD) + Met (MD: -0.69, 95% CI: -1.39, -0.02), and SU + TZD (MD: 0.21; 95% CI: -1.30, 1.71), with no statistical significance. DPP4i + Met demonstrated a non-significant lower incidence of CV events in comparison to TZD + Met (RR: 1.01, 95% CI: 0.46, 2.45) and SU + Met (RR: 1.06, 95% CI: 0.61, 2.06).

Conclusion

DPP4i in combination with Met was efficacious and had a well-tolerated safety profile compared with other traditional OADs. This combination can be considered as a suitable treatment option for patients with T2DM.

Metformin for preventing the progression of chronic kidney disease

BACKGROUND

Metformin has been used in the management of diabetes for decades. It is an effective, low-cost intervention with a well-established safety profile. Emerging evidence suggests that metformin targets a number of pathways that lead to chronic kidney damage, and long-term use may, therefore, slow the rate of kidney function decline and chronic kidney disease (CKD) progression.

OBJECTIVES

To evaluate the effect of metformin therapy on kidney function decline in patients with CKD with or without diabetes mellitus and assess the safety and dose tolerability in this population.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 19 July 2023 with assistance from an Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that reported kidney-related outcomes with a minimum duration of 12 months delivery of the metformin intervention and whose eligibility criteria included adult participants with either i) a diagnosis of CKD of any aetiology and/or ii) those with a diagnosis of diabetes mellitus. Comparisons included placebo, no intervention, non-pharmacological interventions, other antidiabetic medications or any other active control. Studies that included patients on any modality of kidney replacement therapy were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently carried out data extraction using a standard data extraction form. The methodological quality of the included studies was assessed using the Cochrane risk of bias tool. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

This review included 11 studies reporting on 8449 randomised participants. Studies were conducted in patient populations with Autosomal Dominant Polycystic Kidney Disease (ADPKD) (four studies) or diabetes mellitus (seven studies). Six studies compared metformin with no active control, four studies compared metformin with active controls (rosiglitazone, glyburide, pioglitazone, or glipizide), and one study included treatment arms that randomised to either metformin, diet and lifestyle modifications, or other antidiabetic therapies. The risk of bias in included studies varied; two studies were abstract-only publications and were judged to have a high risk of bias in most domains. Other included publications were judged to have a low risk of bias in most domains. Across comparisons, GRADE evaluations for most outcomes were judged as low or very low certainty, except for those relating to side effects, tolerance, and withdrawals, which were judged as moderate certainty. The evidence suggests that compared to placebo, metformin may result in i) a slightly smaller decline in kidney function (3 studies, 505 participants: MD 1.92 mL/min, 95% CI 0.33 to 3.51; I2 = 0%; low certainty), ii) very uncertain effects on the incidence of kidney failure (1 study, 753 participants: RR 1.20, 95% CI 0.17 to 8.49), iii) little or no effect on death (3 studies, 865 participants: RR 1.00, 95% CI 0.76 to 1.32; I2 = 0%; moderate certainty), iv) little or no effect on the incidence of serious adverse events (3 studies, 576 participants: RR 1.15, 95% CI 0.76 to 1.72; I2 = 0%; moderate certainty), and v) likely higher incidence of intolerance leading to study withdrawal than placebo (4 studies, 646 participants: RR 2.19, 95% CI 1.46 to 3.27; I2 = 0%; moderate certainty). The certainty of the evidence for proteinuria was very uncertain. Compared to other active controls (rosiglitazone, glyburide, pioglitazone, or glipizide), metformin i) demonstrated very uncertain effects on kidney function decline, ii) may result in little or no difference in death (3 studies, 5608 participants: RR 0.95 95% CI 0.63 to 1.43; I2 = 0%; low certainty), iii) probably results in little or no difference in intolerance leading to study withdrawal (3 studies, 5593 participants: RR 0.92, 95% CI, 0.79 to 1.08; I2 = 0%; moderate certainty), iv) probably results in little or no difference in the incidence of serious adverse events (2 studies, 5545 participants: RR 1.16, 95% CI 0.79 to 1.71; I2 = 0%; moderate certainty), and v) may increase the urinary albumin-creatinine ratio (2 studies, 3836 participants: MD 14.61, 95% CI 8.17 to 21.05; I2 = 0%; low certainty). No studies reported the incidence of kidney failure.

AUTHORS' CONCLUSIONS

This review highlights the lack of RCTs reporting on the effects of metformin on kidney function, particularly in patients with CKD. Future research in this field requires adequately powered RCTs comparing metformin to placebo or standard care in those with CKD. Seven ongoing studies were identified in this review, and future updates, including their findings, may further inform the results of this review.

Initial Combination Therapy in Type 2 Diabetes

Type 2 diabetes (T2D) is a progressive disease in which it is challenging to achieve long-term durable glycemic control. However, intensive glycemic control is crucial for preventing diabetes-related complications. Previous studies showed that monotherapy with a stepwise add-on approach was seldom effective for long-term durable glycemic control. Combination therapy, which refers to the use of two or more drugs to control hyperglycemia, has multiple benefits, including the ability to target a variety of pathophysiological processes underlying hyperglycemia. In clinical trials, initial combination therapy showed better glycemic control than monotherapy or a stepwise approach. Emerging evidence indicates that initial combination therapy is associated with preserved β-cell function and fewer complications in T2D. However, cost-effectiveness and adverse events with combination therapy are issues that should be considered. Therefore, initial combination therapy is an important option for patients with T2D that clinicians should consider with a view toward balancing benefits and potential harms. In this review, we summarize the literature addressing initial combination therapy in T2D, and we suggest optimal strategies based on clinical situations and patient characteristics.

Premeal almond load decreases postprandial glycaemia, adiposity and reversed prediabetes to normoglycemia: A randomized controlled trial

BACKGROUND

Asian Indians show rapid conversion from prediabetes to type 2 diabetes (T2D). Novel dietary strategies are needed to arrest this progression, by targeting postprandial hyperglycaemia (PPHG).

DESIGN

We conducted a free-living randomized controlled open-label parallel arm study to evaluate the effect of a premeal load of almonds (20 g) 30 min before major meals on anthropometric, glycaemic, and metabolic parameters over 3 months. Sixty-six participants with prediabetes in the age range of 18-60 yrs were recruited. The study was registered at clinicaltrials.gov (registration no. NCT04769726).

RESULTS

Thirty participants in each arm completed the study. As per 'intention-to-treat' analysis, overall additional mean reductions were statistically significant for body weight, BMI, waist circumference (WC), subscapular and suprailiac skinfolds, and improved handgrip strength (Kg) (p < 0·001 for all) in the treatment arm vs. the control arm (after multiple adjustments). In the blood parameters, the additional mean reduction in the treatment arm vs. control arm was statistically significant for fasting and post-75 g oral glucose-load blood glucose, postprandial insulin, HOMA-IR, HbA1c, proinsulin, total cholesterol, and very low-density lipoprotein cholesterol (p < 0·001 for all). Most importantly, we observed a reversal to normoglycemic state (fasting blood glucose and 2 h post-OGTT glucose levels) in 23.3% (7 out of 30) of participants in the treatment arm which is comparable to that seen with Acarbose treatment (25%).

CONCLUSION

Incorporation of 20 g of almonds, 30 min before each major meal leads to significant improvement in body weight, WC, glycemia (particularly PPHG), and insulin resistance and shows potential for reversal of prediabetes to normal glucose regulation over 3 months.

Design of experiment-based LC-MS/MS method development for simultaneous estimation of nateglinide and metformin hydrochloride in rat plasma

This research aims to develop and validate a bioanalytical method for simultaneous estimation of an antidiabetic combination using LC-MS/MS in rat plasma. Nateglinide and metformin hydrochloride are commonly used combination for clinical management of Type 2 diabetes. Hence, simultaneous determination in plasma is essential for the rapid analysis of samples from the pharmacokinetic studies. Statistical optimization was carried out for liquid chromatography (LC) parameters and mass spectroscopic (MS) parameters by design of experiment (DoE) (Design Expert Version 11, Stat Ease Inc., USA) approach. A 33 full factorial design was used for optimization of LC parameters; %methanol, %formic acid, and flow rate were selected as independent variables, whereas peak area and tailing factor were considered as dependent variables for both drugs. Box-Behnken design was used to optimize MS parameters including drying gas flow rate, nebulizing gas flow rate, DL temperature, heat block temperature, and positive voltage as independent factors, and responses selected were [M + H]+ intensity of nateglinide and metformin hydrochloride. The [M + H]+ intensity of the optimized method for nateglinide and metformin hydrochloride were 2,462,838 and 11,873,826, respectively. The model was found significant for optimizing LC and MS parameters with p < 0.05 for both nateglinide and metformin hydrochloride. The optimized method was validated as per the ICH-M10 guideline, which was accurate, precise, and selective. The method was cost-effective and capable of quantitating concentrations in picogram levels for nateglinide and metformin hydrochloride simultaneously.

Association of metformin monotherapy or combined therapy with cardiovascular risks in patients with type 2 diabetes mellitus

Background

Metformin is a first-line drug in type 2 diabetes mellitus (T2DM) treatment, yet whether metformin may increase all-cause or cardiovascular mortality of T2DM patients remains inconclusive.

Methods

We searched PubMed and Embase for data extracted from inception to July 14, 2020, with a registration in PROSPERO (CRD42020177283). This study included randomized controlled trials (RCT) assessing the cardiovascular effects of metformin for T2DM. This study is followed by PRISMA and Cochrane guideline. Risk ratio (RR) with 95% CI was pooled across trials by a random-effects model. Primary outcomes include all-cause mortality and cardiovascular mortality.

Results

We identified 29 studies that randomly assigned patients with 371 all-cause and 227 cardiovascular death events. Compared with untreated T2DM patients, metformin-treated patients was not associated with lower risk of all-cause mortality (RR: 0.98; 95%CI: 0.69–1.38; P = 0.90), cardiovascular mortality (RR: 1.13; 95% CI: 0.60, 2.15; P = 0.70), macrovascular events (RR: 0.87; 95%CI: 0.70–1.07; P = 0.19), heart failure (RR: 1.02; 95% CI:0.61–1.71; P = 0.95), and microvascular events (RR: 0.78; 95% CI:0.54–1.13; P = 0.19). Combination of metformin with another hypoglycemic drug was associated with higher risk of all-cause mortality (RR: 1.49; 95% CI: 1.02, 2.16) and cardiovascular mortality (RR: 2.21; 95% CI: 1.22, 4.00) compared with hypoglycemic drug regimens with no metformin.

Conclusion

The combination of metformin treatment may impose higher risk in all-cause and cardiovascular mortality. This finding, at least in part, shows no evidence for benefits of metformin in combination in terms of all-cause/cardiovascular mortality and cardiovascular events for T2DM. However, the conclusion shall be explained cautiously considering the limitations from UK Prospective Diabetes Study (UKPDS).

Age, sex, disease severity, and disease duration difference in placebo response: implications from a meta-analysis of diabetes mellitus

BACKGROUND

The placebo response in patients with diabetes mellitus is very common. A systematic evaluation needs to be updated with the current evidence about the placebo response in diabetes mellitus and the associated factors in clinical trials of anti-diabetic medicine.

METHODS

Literature research was conducted in Medline, Embase, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov for studies published between the date of inception and June 2019. Randomized placebo-controlled trials conducted in type 1and type 2 diabetes mellitus (T1DM/T2DM) were included. Random-effects model and meta-regression analysis were accordingly used. This meta-analysis was registered in PROSPERO as CRD42014009373.

RESULTS

Significantly weight elevation (effect size (ES) = 0.33 kg, 95% CI, 0.03 to 0.61 kg) was observed in patients with placebo treatments in T1DM subgroup while significantly HbA1c reduction (ES = - 0.12%, 95% CI, - 0.16 to - 0.07%) and weight reduction (ES = - 0.40 kg, 95% CI, - 0.50 to - 0.29 kg) were observed in patients with placebo treatments in T2DM subgroup. Greater HbA1c reduction was observed in patients with injectable placebo treatments (ES = - 0.22%, 95% CI, - 0.32 to - 0.11%) versus oral types (ES = - 0.09%, 95% CI, - 0.14 to - 0.04%) in T2DM (P = 0.03). Older age (β = - 0.01, 95% CI, - 0.02 to - 0.01, P < 0.01) and longer diabetes duration (β = - 0.02, 95% CI, - 0.03 to - 0.21 × 10^-2, P = 0.03) was significantly associated with more HbA1c reduction by placebo in T1DM. However, younger age (β = 0.02, 95% CI, 0.01 to 0.03, P = 0.01), lower male percentage (β = 0.01, 95% CI, 0.22 × 10^-2, 0.01, P < 0.01), higher baseline BMI (β = - 0.02, 95% CI, - 0.04 to - 0.26 × 10^-2, P = 0.02), and higher baseline HbA1c (β = - 0.09, 95% CI, - 0.16 to - 0.01, P = 0.02) were significantly associated with more HbA1c reduction by placebo in T2DM. Shorter diabetes duration (β = 0.06, 95% CI, 0.06 to 0.10, P < 0.01) was significantly associated with more weight reduction by placebo in T2DM. However, the associations between baseline BMI, baseline HbA1c, and placebo response were insignificant after the adjusted analyses.

CONCLUSION

The placebo response in diabetes mellitus was systematically outlined. Age, sex, disease severity (indirectly reflected by baseline BMI and baseline HbA1c), and disease duration were associated with placebo response in diabetes mellitus. The association between baseline BMI, baseline HbA1c, and placebo response may be the result of regression to the mean.

Development and Characterization of Microstructured, Spray-Dried Co-Amorphous Mixture of Antidiabetic Agents Stabilized by Silicate

In the present work, co-amorphous mixture (COAM) of poorly soluble nateglinide (NT) and highly soluble Metformin hydrochloride (MT) was prepared by spray drying method to improve the dissolution rate of NT and the processability of COAM. Binary spray-dried COAM of NT and MT (120 mg: 500 mg) was prepared in its clinical dose ratio whereas 20% Neusilin®US2 (NS) was added to prepare non-sticky, free flowing ternary COAM. Solubility studies of binary and ternary COAM exhibited sevenfold and tenfold rise in the solubility of NT. Complete amorphization of NT was revealed in XRPD and DSC studies of both COAM and hydrogen-bonding interactions were reflected in FTIR-spectra. SEM microphotographs illustrated round-shaped microparticles in ternary COAM against the irregular particles in binary COAM. In vitro dissolution of NT was significantly improved in ternary COAM > binary COAM > NT irrespective of dissolution medium. On contrary, MT has partially transformed to the amorphous form in COAM without altering the solubility. In accelerated stability studies, NT and MT devitrification was not observed in XRPD of ternary COAM in contrast to binary COAM. Therefore, enhanced dissolution of NT, stabilization of spray-dried dispersion, and its improved processability can be achieved by preparing ternary COAM of NT:MT:NS.

Efficacy and Safety of Initial Combination Therapy in Treatment-Naïve Type 2 Diabetes Patients: A Systematic Review and Meta-analysis

INTRODUCTION

The aim of this study was to evaluate the efficacy and safety of initial combination therapy compared with monotherapy in drug-naïve type 2 diabetes patients.

METHODS

MEDLINE, Embase and the Cochrane Central Register of Controlled Trials were searched for randomized clinical trials of initial combination therapy with hypoglycemic agents compared with monotherapy. Those which satisfied the search criteria were included in the meta-analysis. Weighted mean difference and relative risks were calculated.

RESULTS

A total of 36 studies were included in the meta-analysis. Compared with metformin monotherapy, initial combination therapy with metformin plus another anti-diabetes drug exhibited significant reductions in glycated hemoglobin (HbA1c) (p < 0.001). Most of the combination therapies had a similar risk of hypoglycemia (p > 0.05), with the exception of combinations of sulfonylurea/glinide and metformin or combinations of thiazolidinedione and metformin. Compared with dipeptidyl peptidase-4 (DPP-4) inhibitor monotherapy, initial combination therapy with DPP-4 inhibitor plus another anti-diabetes drug showed a significant decrease in HbA1c (p < 0.001) and a similar risk of hypoglycemia (p > 0.05). Compared with monotherapy with other anti-diabetes drugs, initial combination therapies also resulted in significant HbA1c reductions, a similar risk of hypoglycemia and similar risks of other adverse events.

CONCLUSION

Compared with monotherapy, all initial combination therapies resulted in significant HbA1c reductions. Compared with metformin monotherapy, initial combination therapies with DPP-4 inhibitors plus metformin, sodium/glucose cotransporter 2 inhibitors and metformin, respectively, were associated with similar risks of hypoglycemia, but initial combination therapies with sulfonylurea plus metformin, thiazolidinedione and metformin, respectively, were associated with higher risks of hypoglycemia.

FUNDING

AstraZeneca Ltd. (China).

TRIAL REGISTRATION

Registration number CRD42017060717 in PROSPERO.

Should Metformin Remain First-Line Medical Therapy for Patients with Type 2 Diabetes Mellitus and Atherosclerotic Cardiovascular Disease? An Alternative Approach

PURPOSE OF REVIEW

With recent cardiovascular outcome trial (CVOT) results for antihyperglycemic medications, the treatment algorithm for patients with type 2 diabetes (T2DM) and atherosclerotic vascular disease (ASCVD) requires revision.

RECENT FINDINGS

All completed CVOTs have demonstrated CV safety of the tested medications, with some trials demonstrating CV efficacy. While metformin remains the first-line recommended medication for T2DM, 18-37% of the patients enrolled in the completed CVOTs were not treated with metformin, providing substantial power to assess CV outcomes independent of metformin. The safety and tolerability of metformin are indisputable, but there are no robust data proving its efficacy for either macro or microvascular disease outcomes. We should reconsider the primacy of metformin in the management of T2DM in patients with ASCVD. This article will review the evidence for CV effects of antihyperglycemic agents (AHAs), and propose an evidence-based treatment algorithm for patients with T2DM and ASCVD.

Impact of metformin on cardiovascular disease: a meta-analysis of randomised trials among people with type 2 diabetes

AIMS/HYPOTHESIS

Metformin is the most-prescribed oral medication to lower blood glucose worldwide. Yet previous systematic reviews have raised doubts about its effectiveness in reducing risk of cardiovascular disease, the most costly complication of type 2 diabetes. We aimed to systematically identify and pool randomised trials reporting cardiovascular outcomes in which the effect of metformin was 'isolated' through comparison to diet, lifestyle or placebo.

METHODS

We performed an electronic literature search of MEDLINE, EMBASE and the Cochrane Library. We also manually screened the reference lists of previous meta-analyses of trials of metformin identified through a MEDLINE search. We included randomised controlled trials of adults with type 2 diabetes comparing any dose and preparation of oral metformin with no intervention, placebo or a lifestyle intervention and reporting mortality or a cardiovascular outcome.

RESULTS

We included ten articles reporting 13 trials (including a total of 2079 individuals with type 2 diabetes allocated to metformin and a similar number to comparison groups) of which only four compared metformin with placebo and collected data on cardiovascular outcomes. Participants were mainly white, aged ≤65 years, overweight/obese and with poor glycaemic control. Summary estimates were based on a small number of events: 416 myocardial infarctions/ischaemic heart disease events in seven studies and 111 strokes in four studies. The UK Prospective Diabetes Study (UKPDS) contributed the majority of data to the summary estimates, with weights ranging from 52.3% for myocardial infarction to 70.5% for stroke. All outcomes, with the exception of stroke, favoured metformin, with limited heterogeneity between studies, but none achieved statistical significance. Effect sizes (Mantel-Haenszel RR) were: all-cause mortality 0.96 (95% CI 0.84, 1.09); cardiovascular death 0.97 (95% CI 0.80, 1.16); myocardial infarction 0.89 (95% CI 0.75, 1.06); stroke 1.04 (95% CI 0.73, 1.48); and peripheral vascular disease 0.81 (95% CI 0.50, 1.31).

CONCLUSIONS/INTERPRETATION

There remains uncertainty about whether metformin reduces risk of cardiovascular disease among patients with type 2 diabetes, for whom it is the recommended first-line drug. Although this is mainly due to absence of evidence, it is unlikely that a definitive placebo-controlled cardiovascular endpoint trial among people with diabetes will be forthcoming. Alternative approaches to reduce the uncertainty include the use of electronic health records in long-term pragmatic evaluations, inclusion of metformin in factorial trials, publication of cardiovascular outcome data from adverse event reporting in trials of metformin and a cardiovascular endpoint trial of metformin among people without diabetes.

Effect of nateglinide and glimepiride in reducing postprandial hyperglycaemia in patients with type 2 diabetes mellitus

Aim — The purpose of this study was to compare the effect of nateglinide on two-hour post-meal glucose levels with that of glimepiride in patients with type 2 diabetes mellitus. Methods — Glucose and insulin levels were measured during 14-hour profiles (comprising three meal challenges) and intravenous glucose tolerance tests performed before and after five-weeks of treatment with nateglinide (120 mg, a.c.) or glimepiride (1 mg, o.d.) in a randomised, two-centre, double-blind, crossover study in 26 patients with type 2 diabetes and fasting initial glucose levels < 13.9 mmol/L. Results — Mean two-hour postprandial glucose levels were significantly lower during nateglinide treatment than during glimepiride treatment (9.46 vs. 10.00 mmol/L, respectively; p<0.05). The 14-hour incremental glucose area under the curve was -2.2 mmol•h/L during nateglinide treatment and +6.2 mmol•h/L during glimepiride treatment (p<0.01). Nateglinide improved both the early insulin response during meals and the acute insulin response during intravenous glucose tolerance tests, restoring the biphasic insulin secretion pattern. Both insulin secretagogues improved intravenous glucose tolerance relative to the pre-treatment period, but only nateglinide restored a biphasic insulin profile. Conclusions — By restoring a more physiological post-load insulin response, nateglinide is more effective than glimepiride in controlling postprandial glucose excursions.

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.

Co-Amorphous Combination of Nateglinide-Metformin Hydrochloride for Dissolution Enhancement

The aim of the present work was to prepare a co-amorphous mixture (COAM) of Nateglinide and Metformin hydrochloride to enhance the dissolution rate of poorly soluble Nateglinide. Nateglinide (120 mg) and Metformin hydrochloride (500 mg) COAM, as a dose ratio, were prepared by ball-milling technique. COAMs were characterized for saturation solubility, amorphism and physicochemical interactions (X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR)), SEM, in vitro dissolution, and stability studies. Solubility studies revealed a sevenfold rise in solubility of Nateglinide from 0.061 to 0.423 mg/ml in dose ratio of COAM. Solid-state characterization of COAM suggested amorphization of Nateglinide after 6 h of ball milling. XRPD and DSC studies confirmed amorphism in Nateglinide, whereas FTIR elucidated hydrogen interactions (proton exchange between Nateglinide and Metformin hydrochloride). Interestingly, due to low energy of fusion, Nateglinide was completely amorphized and stabilized by Metformin hydrochloride. Consequently, in vitro drug release showed significant increase in dissolution of Nateglinide in COAM, irrespective of dissolution medium. However, little change was observed in the solubility and dissolution profile of Metformin hydrochloride, revealing small change in its crystallinity. Stability data indicated no traces of devitrification in XRPD of stability sample of COAM, and % drug release remained unaffected at accelerated storage conditions. Amorphism of Nateglinide, proton exchange with Metformin hydrochloride, and stabilization of its amorphous form have been noted in ball-milled COAM of Nateglinide-Metformin hydrochloride, revealing enhanced dissolution of Nateglinide. Thus, COAM of Nateglinide-Metformin hydrochloride system is a promising approach for combination therapy in diabetic patients.

Pharmacologic treatment of type 2 diabetes: oral medications

OBJECTIVE

To review the oral and injectable pharmacologic treatment options for type 2 diabetes.

DATA SOURCES

A literature search was conducted using PubMed electronic database for studies published in English between 1993 and September 2014. Search terms included diabetes mellitus, type 2 diabetes, and the individual name for each antidiabetic medication reviewed. In addition, manual searches were performed for cross-references from publications. Package inserts, United States Food and Drug Administration (FDA) Web site, Institute for Safe Medication Practices Web site, American Diabetes Association Web site and scientific session poster presentations, and individual drug company Web pages were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

This review focused on information elucidated over the past 10 years to assist prescribers in choosing optimal therapy based on individual patient characteristics. Studies leading to the approval of or raising safety concerns for the antidiabetic medications reviewed in this article were included.

DATA SYNTHESIS

In the past 10 years, there have been 4 novel oral antidiabetic medication classes and 9 new injectable agents and insulin products approved by the FDA for the treatment of type 2 diabetes as well as new information regarding the safety and use of several older antidiabetic medication classes. The distinctions were reviewed for each individual agent, and a comparison was completed if there was more than one agent in a particular therapeutic class. Using current information available, select investigational agents in phase III trials or those with a pending new drug application were highlighted.

CONCLUSION

There are now 9 distinct oral pharmacologic classes and a variety of insulin and noninsulin injectable medications available for the treatment of type 2 diabetes. Metformin remains the first-line treatment option for most patients. When considering options for alternative or additional treatment, prescribers must weigh the benefits and risks using individual patient characteristics.

Differing effects of metformin on glycemic control by race-ethnicity

CONTEXT

Metformin is considered first-line treatment for type 2 diabetes mellitus. However, little is known about its effects in African American individuals.

OBJECTIVE

The objective of the study was to assess whether metformin's effect on glycemic control differs by race-ethnicity Design: Electronic health records were used to identify adults who had a diagnosis of diabetes, two or more fills of metformin, and two or more glycated hemoglobin (HbA1c) measurements. Pharmacy claims were used to estimate metformin exposure based on fill frequency and dose dispensed. Regression analyses modeled the relationship between metformin exposure and HbA1c levels. Analyses were stratified by race-ethnicity and baseline HbA1c values.

SETTING

The study was conducted at a large health system in southeast Michigan.

MAIN OUTCOME MEASURE

Differences in HbA1c levels while on metformin were measured.

RESULTS

We identified 19 672 patients with diabetes taking metformin; 7429 were African American and 8783 were European American. Baseline HbA1c values in these two groups were 7.81% (61.8 mmol/mol) and 7.38% (57.1 mmol/mol), respectively. Compared with no use, metformin was associated with a 0.62% (6.8 mmol/mol) reduction in HbA1c; however, there was a significant difference by race-ethnicity (P < .001). Among African American individuals, metformin use was associated with a 0.90% (9.8 mmol/mol) reduction in HbA1c levels, whereas among European Americans, metformin was associated with a 0.42% (4.6 mmol/mol) reduction. Irrespective of baseline HbA1c, metformin use was associated with lower HbA1c levels in African American individuals.

CONCLUSIONS

African American individuals appear to have a better glycemic response to metformin when compared with European Americans. Further studies are needed to determine whether this translates to commensurate reductions in diabetes complications.

Effect of the combination of mitiglinide and metformin on glycemic control in patients with type 2 diabetes mellitus

Aims/Introduction:  Mitiglinide is the newest drug in the meglitinide family. It increases the early-phase insulin release through rapid association-dissociation kinetics in the pancreatic β cells. The efficacy and safety of adding meglitinide to metformin monotherapy in patients with type 2 diabetes are unknown.

MATERIALS AND METHODS

  We carried out a prospective, randomized, multicenter trial to assess the efficacy and safety of combined treatment with mitiglinide and metformin for patients with type 2 diabetes who showed inadequate glycemic control with metformin monotherapy. Subjects with glycated hemoglobin (HbA1c) >7.0% after an 8-week metformin run-in phase were randomized to a 16-week trial phase with metformin plus mitiglinide (Met + Mit) or metformin plus placebo (Met + Pcb).

RESULTS

  Compared with the Met + Pcb group, the Met + Mit group showed a greater reduction in HbA1c (-0.7 ± 0.6%vs-0.4 ± 0.7%, P = 0.002), fasting plasma glucose (-0.77 ± 1.76 mmol/L vs-0.05 ± 1.60 mmol/L, P = 0.015) and 2-h postprandial glucose (-3.76 ± 3.57 mmol/L vs-0.84 ± 3.07 mmol/L, P < 0.0001). The proportion of the patients who achieved the target HbA1c value of <7% at the end of the study was also higher in the Met + Mit group than the Met + Pcb group (49.3%vs 28.8%, P = 0.016). There were no differences in the adverse event rates between groups.

CONCLUSIONS

  Combination therapy with metformin and mitiglinide is effective and safe for the treatment of patients with type 2 diabetes who have inadequate glycemic control with metformin monotherapy. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00023.x, 2010).

Repaglinide, but not nateglinide administered supraspinally and spinally exerts an anti-diabetic action in d-glucose fed and streptozotocin-treated mouse models

We have recently demonstrated that some anti-diabetic drugs such as biguanide and thizolidinediones administered centrally modulate the blood glucose level, suggesting that orally administered anti-diabetic drugs may modulate the blood glucose level by acting on central nervous system. The present study was designed to explore the possible action of another class of anti-diabetic drugs, glinidies, administered centrally on the blood glucose level in ICR mice. Mice were administered intracerebroventricularly (i.c.v.) or intrathecally (i.t.) with 5 to 30 µg of repaglinide or nateglinide in D-glucose-fed and streptozotocin (STZ)-treated models. We found that i.c.v. or i.t. injection with repaglinide dose-dependently attenuated the blood glucose level in D-glucose-fed model, whereas i.c.v. or i.t. injection with nateglinide showed no modulatory action on the blood glucose level in D-glucose-fed model. Furthermore, the effect of repaglinide administered i.c.v. or i.t. on the blood glucose level in STZ-treated model was studied. We found that repaglinide administered i.c.v. slightly enhanced the blood glucose level in STZ-treated model. On the other hand, i.t. injection with repaglinide attenuated the blood glucose level in STZ-treated model. The plasma insulin level was enhanced by repaglinide in D-glucose-fed model, but repaglinide did not affect the plasma insulin level in STZ-treated model. In addition, nateglinide did not alter the plasma insulin level in both D-glucose-fed and STZ-treated models. These results suggest that the anti-diabetic action of repaglinide appears to be, at least, mediated via the brain and the spinal cord as revealed in both D-glucose fed and STZ-treated models.

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.

Efficacy and safety of nateglinide plus vildagliptin combination therapy compared with switching to vildagliptin in type 2 diabetes patients inadequately controlled with nateglinide

Aims/Introduction

To investigate the efficacy and safety of vildagliptin, a potent dipeptidyl peptidase‐4 inhibitor, as add‐on to nateglinide, compared with switching to vildagliptin in Japanese type 2 diabetes patients poorly controlled with nateglinide.

Materials and Methods

A total of 40 patients inadequately controlled with nateglinide were randomized to the switching group (n = 20, switching from nateglinide to vildagliptin) or combination group (n = 20, nateglinide plus vildagliptin). A meal tolerance test was carried out at weeks 0 and 24.

Results

The mean changes in glycated hemoglobin from baseline to week 24 were −1.2 ± 0.3% and −0.3 ± 0.5% in patients of the combination and switching groups, respectively, and the difference between the groups was statistically significant (P < 0.001). The mean changes in area under the curve of glucose from 0 to 180 min (AUC_0–180 min) from baseline to week 24 was −361 ± 271.3 mmol·min/L in patients of the combination group compared with 141 ± 241.9 mmol·min/L in those of the switching group (P < 0.001). The incidence of hypoglycemic events was low (three in the combination group), and none of the patients developed severe hypoglycemia. Although the addition of vildagliptin to nateglinide did not significantly increase insulin secretion relative to glucose elevation (ISG) after meal load (ISG_0–180 min: AUC_0–180 min insulin / AUC_0–180 min glucose) in comparison with that in baseline, the mean ISG_0–30 min 24 weeks after addition of vildagliptin to nateglinide was significantly higher than that at baseline. In contrast, switching from nateglinide to vildagliptin reduced the mean ISG_0–180 min, relative to baseline.

Conclusions

The combination therapy of vildagliptin and nateglinide is effective and safe in Japanese type 2 diabetes, and the improved glycemic control is as a result of augmentation of nateglinide‐induced early phase insulin secretion. This trial was registered with UMIN (no. ID000004010).

The role of nateglinide and repaglinide, derivatives of meglitinide, in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is one of the most common chronic diseases worldwide, presenting a great challenge to the public health systems due to high morbidity and mortality, because of frequent micro-/macro-vascular complications. Many treatment options are now available, with different efficacy as well as mechanisms of action to improve deranged glucose metabolism. We review some of the available data on derivatives of meglitinide, namely nateglinide and repaglinide. These two compounds increase insulin secretion by a mechanism similar to the one of sulfonylureas, but with a shorter half-life. Nateglinide and repaglinide, derivatives of meglitinides, have characteristic pharmacodynamic and pharmacokinetic properties that, together with their proposed mechanism of action, make them useful for type 2 diabetes mellitus, especially when used in combination therapy.

Effect of Pramlintide on Weight in Overweight and Obese Insulin-Treated Type 2 Diabetes Patients

OBJECTIVE

Several randomized, placebo-controlled, double-blind trials in insulin-treated patients with type 2 diabetes have shown that adjunctive therapy with pramlintide reduces hemoglobin (Hb)A1c with concomitant weight loss. This analysis further characterizes the weight-lowering effect of pramlintide in this patient population.

RESEARCH METHODS AND PROCEDURES

This pooled post hoc analysis of two long-term trials included all patients who were overweight/obese at baseline (BMI > 25 kg/m2), and who were treated with either 120 microg pramlintide BID (n = 254; HbA1c 9.2%; weight, 96.1 kg) or placebo (n = 244; HbA1c 9.4%; weight, 95.0 kg). Statistical endpoints included changes from baseline to week 26 in HbA1c, body weight, and insulin use.

RESULTS

Pramlintide treatment resulted in significant reductions from baseline to week 26, compared with placebo, in HbA1c and body weight (both, p < 0.0001), for placebo-corrected reductions of -0.41% and -1.8 kg, respectively. Approximately three times the number of patients using pramlintide experienced a > or = 5% reduction of body weight than with placebo (9% vs. 3%, p = 0.0005). Patients using pramlintide also experienced a proportionate decrease in total daily insulin use (r = 0.39, p < 0.0001). The greatest placebo-corrected reductions in weight at week 26 were observed in pramlintide-treated patients with a BMI >40 kg/m2 and in those concomitantly treated with metformin (both, p < 0.001), for placebo-corrected reductions of -3.2 kg and -2.5 kg, respectively.

DISCUSSION

These findings support further evaluation of the weight-lowering potential of pramlintide in obese patients with type 2 diabetes.

Non-linear contribution of glucose measures to cardiovascular diseases and mortality: reclassifying the Framingham's risk categories: a decade follow-up from the Tehran lipid and glucose study

BACKGROUND

We investigated non-linear contribution of fasting plasma glucose (FPG) and 2-hour post-challenge plasma glucose (2h-PCPG) to the risk of CVD and mortality. We hypothesized that glucose measures improve risk-stratification made by the Framingham's general CVD risk algorithm.

METHODS

Among participants aged ≥ 30 (n=8071), not taking glucose-lowering agents, 6169 (3477 women) remained eligible. Non-linear contribution of FPG and 2h-PCPG to incident CVD and mortality were assessed using Cox models incorporating restricted cubic splines functions. Risk reclassification improvement conferred by FPG and 2h-PCPG was examined using an extended version of net reclassification index (NRI) that takes into account the censoring nature of survival data.

RESULTS

We documented 465 incident CVD events (402 CHD), 212 deaths from any cause (94 CVD deaths). Excluding the contribution of the 2h-PCGP to mortality (that was linear) dose-response relationships between glucose measures and CVD and mortality were curvilinear with nadirs below which decreasing levels of glucose were unlikely to offer any benefit. These nadirs were assigned to FPG of 4.9-5.3 and 2h-PCPG of 6.0 mmol.l(-1). Glucose measures added to the predictive ability of the Framingham's general CVD risk algorithm with cutpoint-free NRIs ranging from 19 to 54%.

CONCLUSION

Glucose measures contributed to the risk of CVD and mortality in a curvilinear fashion, we observed increased risk below glucose thresholds currently used to define diabetes, supporting criteria for the diagnosis of impaired fasting glycemia and impaired glucose tolerance. Glucose measures were observed to add to predictive ability of the predictive model which included established cardiovascular risk factors.

Reappraisal of metformin efficacy in the treatment of type 2 diabetes: a meta-analysis of randomised controlled trials

BACKGROUND

The UK Prospective Diabetes Study showed that metformin decreases mortality compared to diet alone in overweight patients with type 2 diabetes mellitus. Since then, it has been the first-line treatment in overweight patients with type 2 diabetes. However, metformin-sulphonylurea bitherapy may increase mortality.

METHODS AND FINDINGS

This meta-analysis of randomised controlled trials evaluated metformin efficacy (in studies of metformin versus diet alone, versus placebo, and versus no treatment; metformin as an add-on therapy; and metformin withdrawal) against cardiovascular morbidity or mortality in patients with type 2 diabetes. We searched Medline, Embase, and the Cochrane database. Primary end points were all-cause mortality and cardiovascular death. Secondary end points included all myocardial infarctions, all strokes, congestive heart failure, peripheral vascular disease, leg amputations, and microvascular complications. Thirteen randomised controlled trials (13,110 patients) were retrieved; 9,560 patients were given metformin, and 3,550 patients were given conventional treatment or placebo. Metformin did not significantly affect the primary outcomes all-cause mortality, risk ratio (RR)=0.99 (95% CI: 0.75 to 1.31), and cardiovascular mortality, RR=1.05 (95% CI: 0.67 to 1.64). The secondary outcomes were also unaffected by metformin treatment: all myocardial infarctions, RR=0.90 (95% CI: 0.74 to 1.09); all strokes, RR=0.76 (95% CI: 0.51 to 1.14); heart failure, RR=1.03 (95% CI: 0.67 to 1.59); peripheral vascular disease, RR=0.90 (95% CI: 0.46 to 1.78); leg amputations, RR=1.04 (95% CI: 0.44 to 2.44); and microvascular complications, RR=0.83 (95% CI: 0.59 to 1.17). For all-cause mortality and cardiovascular mortality, there was significant heterogeneity when including the UK Prospective Diabetes Study subgroups (I(2)=41% and 59%). There was significant interaction with sulphonylurea as a concomitant treatment for myocardial infarction (p=0.10 and 0.02, respectively).

CONCLUSIONS

Although metformin is considered the gold standard, its benefit/risk ratio remains uncertain. We cannot exclude a 25% reduction or a 31% increase in all-cause mortality. We cannot exclude a 33% reduction or a 64% increase in cardiovascular mortality. Further studies are needed to clarify this situation.

Cost-effectiveness study of oral hypoglycemic agents in the treatment of outpatients with type 2 diabetes attending a public primary care clinic in Mexico City

INTRODUCTION

Worldwide, diabetes mellitus presents a high burden for individuals and society. In Latin America, many people with diabetes have limited access to health care, which means that indirect costs may exceed direct health care cost. Diabetes is Mexico's leading cause of death.

PURPOSE

To evaluate the cost-effectiveness ratios of the most used oral hypoglycemic agents (OHA) in the treatment of outpatients with type 2 diabetes attending a public primary care clinic in Mexico City.

DESIGN

A cross-sectional and analytic study was conducted in Mexico City.

METHODOLOGY

Twenty-seven adult outpatients with type 2 diabetes who were treated either with metformin or glibenclamide were included. Acarbose was used as an alternative strategy. The study was carried out from the perspective of Mexican society. Direct medical and nonmedical costs as well as indirect costs were evaluated using a structured questionnaire. Efficacies of all drug treatments were evaluated retrospectively. A systematic search was conducted to select published randomized clinical trials based on predetermined inclusion criteria, and treatment success was defined as glycosylated hemoglobin factor ≤ 7%. Efficacy data of each drug and/or combination were analyzed using meta-analysis. The Monte Carlo Markov model was used. Quality-adjusted life-years (QALY) were used as the unit of effectiveness; incremental and sensitive analyses were performed and a 5% discount rate was calculated. A hypothetical cohort of 10,000 patients was modeled.

RESULTS

The odds ratios of the success of each drug treatment were obtained from the meta-analyses, and were the following: 5.82 (glibenclamide), 3.86 (metformin), 3.5 (acarbose), and 6.76 (metformin-glibenclamide). The cost-effectiveness ratios found were US$272.63/QALY (glibenclamide), US$296.48/QALY (metformin), and US$409.86/QALY (acarbose). Sensitivity analysis did not show changes for the most cost-effective therapy when the effectiveness probabilities or treatment costs were modified.

CONCLUSION

Glibenclamide is the most cost-effective treatment for the present study outpatient population diagnosed with type 2 diabetes in the early stages.

Drug-induced hypoglycaemia: an update

Drugs are the most frequent cause of hypoglycaemia in adults. Although hypoglycaemia is a well known adverse effect of antidiabetic agents, it may occasionally develop in the course of treatment with drugs used in everyday clinical practice, including NSAIDs, analgesics, antibacterials, antimalarials, antiarrhythmics, antidepressants and other miscellaneous agents. They induce hypoglycaemia by stimulating insulin release, reducing insulin clearance or interfering with glucose metabolism. Several drugs may also potentiate the hypoglycaemic effect of antidiabetic agents. Administration of these agents to individuals with diabetes mellitus is of most concern. Many of these drugs, and depending on clinical setting, may also induce hyperglycaemia. Drug-induced hepatotoxicity and nephrotoxicity may lead in certain circumstances to hypoglycaemia. Some drugs may also induce hypoglycaemia by causing pancreatitis. Drug-induced hypoglycaemia is usually mild but may be severe. Effective clinical management can be handled through awareness of this drug-induced adverse effect on blood glucose levels. Herein, we review pertinent clinical information on the incidence of drug-induced hypoglycaemia and discuss the underlying pathophysiological mechanisms, and prevention and management.

Additive hypoglycaemic effect of nateglinide and exogenous glucagon-like peptide-1 in type 2 diabetes

We examined the postprandial glucose regulators nateglinide and GLP-1, separately and in combination, in people with type 2 diabetes. Nateglinide inhibited DPP-4 activity, reduced GLP-1 degradation and enhanced its insulinotropic and blood glucose lowering effect. Combining nateglinide and GLP-1 derivatives may effectively control postprandial glycaemia.

Simple pharmacometric tools for oral anti-diabetic drug development: competitive landscape for oral non-insulin therapies in type 2 diabetes

The objectives were to develop a translational model that will help select doses for Phase-3 trials based on abbreviated Phase-2 trials and understand the competitive landscape for oral anti-diabetics based on efficacy, tolerability and ability to slow disease progression. Data for eight anti-diabetics with temporal profiles for fasting plasma glucose (FPG) and hemoglobin A1c (HbA1c) from 12 publications were digitized. The monotherapy data consisted of FPG and HbA1c profiles that were modeled using a transit compartment model. Evaluation of the competitive landscape utilized HbA1c literature data for 11 drugs. For the safety metric, tolerability issues with anti-diabetic drug classes were tabulated. For disease progression, the coefficient of failure method was used for assessing data from two long-term trials. The transit rate constants were remarkably consistent across 12 trials and represent system-specific/drug-independent parameters. The competitive landscape analysis showed that the primary efficacy metric fell into two groups of DeltaHbA1c: >0.8% or approximately 0.8%. On the safety endpoints, older agents showed some tolerability issues while the new agents were relatively safe. Among the different drug classes, only the thiazolidinediones appeared to slow disease progression but may also increase heart failure risk. In conclusion, the ability of system-specific parameters to predict HbA1c provides a tool to predict the expected efficacy profile from abbreviated dose-finding trials. To be commercially viable, new drugs should improve DeltaHbA1c by about 0.8% or more and possess safety profiles similar to newer anti-diabetic agents. Thus, this study proposes a suite of simple yet powerful tools to guide type-2-diabetes drug development.

Regulatory challenges for new drugs to treat obesity and comorbid metabolic disorders

Obesity is a major cause of morbidity and mortality through cardio- and cerebrovascular diseases and cancer. The metabolic consequences of obesity include dyslipidaemia, hypertension, proinflammatory atherogenesis, pre-diabetes and Type 2 diabetes. For a significant proportion of patients, pharmacotherapy to tackle obesity is required as adjunctive support to diet, exercise and lifestyle modification. To this end, the pharmaceutical industry is pursuing many novel drug targets. Although this view is probably not justified, the recent tribulations of rimonabant have created a perception that the regulatory bar for the approval of antiobesity drugs has been raised. Although >5% of placebo-subtracted weight loss maintained over 1 year is the primary efficacy end-point, it is improvements in cardiovascular risk factors that the Food and Drug Administration (FDA) and European Medicines Agency (EMEA) require to grant approval. Safety aspects are also critical in this indication. Many companies are now switching development of their antiobesity drug candidates into other metabolic disorders. Type 2 diabetes is accepted by the industry and FDA, but not EMEA, as the most appropriate alternative. On the other hand, improvements in plasma lipids produced by antiobesity drugs are moderate compared with established therapies, suggesting dyslipidaemia is not a viable development option. Metabolic Syndrome is not accepted by FDA or EMEA as a discrete disease and the agencies will not licence antiobesity drugs for its treatment. The regulatory environment for antiobesity drugs and the spectrum of indications for which they can be approved could change dramatically if positive data for sibutramine emerge from the SCOUT outcome trial.

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

BACKGROUND

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

OBJECTIVES

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

SEARCH STRATEGY

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

OBJECTIVES

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

SEARCH STRATEGY

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Future perspectives for insulinotropic agents in the treatment of type 2 diabetes-DPP-4 inhibitors and sulphonylureas

The introduction of dipeptidyl-peptidase IV inhibitors (DPP-4 inhibitors) brought a novel class of insulinotropic agents into the treatment options for type 2 diabetes. This paper compares the actions, clinical efficacy and safety of sulphonylureas with those of the DPP-4 inhibitors. First, the mode of action of both classes of antidiabetic agents is described. Then clinical studies for both substances in monotherapy and combination therapies are compared concerning their effects on glycaemic parameters and long-term duration of action. Hypoglycaemia incidence and other adverse effects are compared and data on cardiovascular parameters and endpoints are summarized. The effects of sulphonylureas and DPP-4 inhibitors on beta-cell function and beta-cell mass are highlighted. The present and future indications for both sulphonylureas and DPP-4 inhibitors are discussed.

Nateglinide versus repaglinide for type 2 diabetes mellitus in China

The purpose of this study is to evaluate efficacy and safety of nateglinide tablet administration in comparison with those of repaglinide tablet as control on treating type 2 diabetes mellitus in China. Pooled-analysis with analysis of covariance (ANCOVA) method was applied to assess the efficacy and safety based on original data collected from four independent randomized clinical trials with similar research protocols. However meta-analysis was applied based on the outcomes of the four studies. The results by meta-analysis were comparable to those obtained by pooled-analysis. The means of HbA(1c), and fasting blood glucose in both the nateglinide and repaglinide groups were reduced significantly after 12 weeks duration but no statistical differences in reduction between the two groups. The adverse reaction rates were 9.89 and 6.51% in the nateglinide and repaglinide groups respectively, with the rate difference showing no statistical significance, and the Odds Ratio of adverse reaction rate (95% confidence interval) was 1.59 (0.99, 2.55). Both nateglinide and repaglinide administration have similarly significant effects on reducing HbA(1c) and FBG. However, the adverse reaction rate in the nateglinide group is higher than that in the latter using repaglinide but no statistical significance difference as revealed in the four clinical trials detailed below.

Combination of nateglinide with thiazolidinediones in Type 2 diabetes

Insulin sensitivity and insulin secretion are reciprocally related such that insulin resistance is adapted by increased insulin secretion to maintain normal glucose and lipid homeostasis. Treatment of Type 2 diabetes should aim to restore and sustain the normal relationship between insulin sensitivity and secretion. Nateglinide is a rapid-onset, short-acting insulin-secretion enhancer that restores early-phase insulin secretion, reduces postprandial glucose excursions and prevents long-term hyperinsulinemia. Given its mechanism of action, it is evident that nateglinide would be more effective when used in combination with an insulin sensitizer, such as the thiazolidinediones. Thiazolidinediones do not stimulate insulin release and, therefore, are potentially suitable candidates for combination therapy with an insulin-secretion enhancer, such as nateglinide. Combination therapy of thiazolidinediones with nateglinide is effective, carries low risk of hypoglycemia and is suitable for patients with moderate renal impairment, although weight gain and edema are common side effects. Further studies are needed to determine whether nateglinide in combination with thiazolidinediones will help clinicians better achieve their treatment goals in targeting Type 2 diabetes. Moreover, comparative studies between nateglinide and medications targeting postprandial glycemia, such as dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 analogues, are necessary. This article summarizes data concerning the mechanism of action, efficacy and safety of therapy with nateglinide and thiazolidinediones as monotherapy and in combination treatment, and aims at a better understanding of the substrate defects their synergy hopes to defy.

Self-monitoring of blood glucose in diabetes mellitus: arguments for an individualized approach

BACKGROUND

The utility of glucose self-monitoring in different types and stages of diabetes is controversial, as there is only sparse relevant evidence from randomized controlled clinical trials. In this analysis, the authors aim to develop individualized recommendations based on clinical needs and the available literature.

METHODS

The PubMed database was searched for articles that appeared up to 30 September 2008 containing the terms "measurement," "control","monitoring," and "hypoglycemia"; the retrieved articles were supplemented by other articles that were cited in them. A directed search was also made for the recommendations of the German, European, American, and international diabetological societies. Conclusions were then drawn about the useful modalities and extent of glucose self-monitoring on the basis of the clinical features of the major types of diabetes and the main treatment strategies for them.

RESULTS

With the exception of intensified treatment strategies (which rely on blood-sugar regulation with insulin), only a few evidence-based recommendations can be derived from randomized clinical trials and meta-analyses. Nonetheless, a strategy for self-monitoring according to the patient's individual needs can be derived from the characteristics of therapeutic regimens: depending on the type of diabetes from which the patient suffers, the predicted number of glucometer strips required for self-monitoring will vary from almost none to roughly 400 per month.

CONCLUSIONS

The decision to use glucose self-monitoring, as well as the type and extent of self-monitoring that will be used, should be based on the individual patient's type of diabetes, treatment regimen, and clinical characteristics. Like any other type of therapeutic intervention, self-monitoring should have a well-documented, rational justification.

Safety and efficacy of nateglinide/metformin combination therapy in the treatment of type 2 diabetes

The increasing prevalence of type 2 diabetes provides impetus for both development of new drugs to improve glycemic control and for reconsideration of treatment strategies with existing agents. Combination therapy with complementary drug classes that act on different aspects of glycemic control has been a particularly effective strategy. This work reviews the published literature reporting efficacy and safety/tolerability of nateglinide, a rapid-onset insulinotropic agent with a predominant effect to reduce postprandial glucose, when combined with metformin, a first-line agent that suppresses hepatic glucose production and thereby reduces fasting plasma glucose. The nateglinide/metformin combination has consistently been found to be both efficacious and well tolerated, whether given as initial combination therapy in drug-naïve patients or when added to metformin monotherapy. Maximum efficacy (Δ glycosylated hemoglobin [HbA_1c]= −1.4% to −1.9%, sustained for up to 2 years of treatment) was seen in studies of drug-naïve patients in whom pharmacotherapy was initiated with the combination of nateglinide and metformin, and modest reductions in HbA_1c (Δ = −0.5% to −1.2%, sustained for up to 24 weeks) were found when nateglinide was added to ongoing metformin monotherapy.

Conclusion: the combination of nateglinide and metformin provides a sustained degree of glycemic control not achievable with either agent given as monotherapy.

Nateglinide combination therapy with basal insulin and metformin in patients with Type 2 diabetes

AIMS

To compare the effect of adding nateglinide or placebo on postprandial glucose excursions (PPGEs), glycated haemoglobin (HbA(1c)), diurnal glucose profiles and hypoglycaemia in patients with Type 2 diabetes treated with the combination of basal insulin and metformin.

RESEARCH DESIGN AND METHODS

This was an investigator-initiated, double-blind, randomized, parallel-group, study in five centres. Patients with Type 2 diabetes (n = 88, age 56.0 +/- 0.9 years, duration of diabetes 9.4 +/- 0.5 years, HbA(1c) 7.8 +/- 0.1%, body mass index 32.4 +/- 0.5 kg/m(2)) treated with basal insulin and metformin entered a 24-week period, during which basal insulin was titrated to optimize glucose control. Thereafter, the patients were randomized to receive either nateglinide (120 mg three times daily) or placebo before their main meals for 24 weeks.

RESULTS

During the optimization period, HbA(1c) decreased by -0.3 +/- 0.1 and -0.4 +/- 0.2% (NS) and insulin doses increased by 10.0 IU (2.0-32.0) [0.09 IU/kg (0.02-0.34)] and 10.0 IU (0.0-19.0) [0.11 IU/kg (0.0-0.25)] (NS) in the nateglinide and placebo groups. Mean postprandial glucose during weeks 20-24 averaged 9.0 +/- 0.3 and 10.0 +/- 0.3 mmol/l in the nateglinide and placebo groups (P = 0.025) and mean PPGE averaged 2.4 +/- 0.2 and 3.1 +/- 0.2 mmol/l, respectively (P = 0.019). At 24 weeks as compared with 0 weeks, mean HbA(1c) had decreased by 0.41 +/- 0.12% in the nateglinide group and by 0.04 +/- 0.12% in the placebo group (P = 0.023). The frequency of confirmed, symptomatic hypoglycaemia was 7.7 episodes/patient-year vs. 4.7 episodes/patient-year in the nateglinide and placebo groups (P = 0.031).

CONCLUSIONS

Addition of a short-acting insulin secretagogue at main meals improves postprandial hyperglycaemia during combination therapy with basal insulin and metformin, but increases the frequency of hypolycaemia.