Influence of initial hyperglycaemia, weight and age on the blood glucose lowering efficacy and incidence of hypoglycaemic symptoms with a single-tablet metformin-glibenclamide therapy (Glucovance) in type 2 diabetes

Association of Met420del Variant of Metformin Transporter Gene SLC22A1 with Metformin Treatment Response in Ethiopian Patients with Type 2 Diabetes

Objective

This study aimed to evaluate whether the M420del variants of SLC22A1 (rs72552763) is associated with metformin treatment response in Ethiopian patients with type 2 diabetes mellitus (T2DM).

Patients and Methods

A prospective observational cohort study was conducted on 86 patients with T2DM who had been receiving metformin monotherapy for <1 year. Patients showing ≥0.5% reduction in HbA1c levels from baseline within 3 months and remained low for at least another 3 months were defined as responders while those patients with <0.5% reduction in HbA1c levels and/or those whom started a new class of glucose-lowering drug(s) because of unsatisfactory reduction were defined as non-responders. In addition, good glycemic control was observed when HbA1c ≤7.0%, and the above values were regarded as poor. Genotyping of rs72552763 SNP was performed using TaqMan® Drug Metabolism Enzyme Genotyping Assay and its association with metformin response and glycemic control were assessed by measuring the change in HbA1c and fasting blood glucose levels using Chi-square, logistic regression and Mann-Whitney U-test. Statistical significance was set at p <0.05.

Results

The minor allele frequency of the rs72552763 SNP of SLC22A1 was 9.3%. Metformin response was significantly higher in deletion_GAT (del_G) genotypes as compared to the wild-type GAT_GAT (G_G) genotypes. Furthermore, a significantly lower median treatment HbA1 level was found in del_G genotypes as compared to G_G genotypes. However, the association of rs72552763 with metformin response was not replicated at the allele level. In contrast, the minor del_allele was significantly associated with good glycemic control compared to the G_allele, though not replicated at del_G genotypes level.

Conclusion

This study demonstrated that metformin response was significantly higher in study participants with a heterozygous carrier of M420del variants of SLC22A1 as compared to the wild-type G_G genotypes after 3 months of treatment.

Patient-factors associated with metformin steady-state levels in type 2 diabetes mellitus with therapeutic dosage

AIMS

This prospective study aimed to analyze metformin steady-state concentration in repeated constant dosage and the influencing patient-factors as well as to correlate them with glycemic control.

METHODS

The validated HPLC-UV method was used to examine metformin steady-state concentration, while FBG and glycated albumin were used as the parameters of glycemic control during metformin administration.

RESULTS

A total of 82 type-2 diabetes patients were involved with 32.1% of them having metformin Cssmin and 84.1% having Cssmax of metformin within the recommended therapeutic range. One patient had metformin Css that exceeded minimum toxic concentration despite his normal renal function and administered therapeutic dosage of metformin. Higher Cssmax was found in patients with metformin monotherapy, while patients with longer duration of metformin use had significantly higher Cssmin.

CONCLUSIONS

Along with initial hyperglycemia and eGFR, metformin Cssmin became the only parameter that influenced FBG level (P < 0.05). Duration of previous metformin use should be considered in the strategy of optimizing metformin dosage. The type-2 diabetes patients with obesity are more suggested to take shorter interval of metformin administration (or possibly with sustained-release formulation) to keep Cssmin within the therapeutic range.

Baseline HbA1c predicts attainment of 7.0% HbA1c target with structured titration of insulin glargine in type 2 diabetes: a patient-level analysis of 12 studies

AIMS

To determine whether baseline characteristics, especially haemoglobin A1c (HbA1c), predict the likelihood of reaching HbA1c ≤ 7.0% or the risk of experiencing hypoglycaemia after the addition of insulin glargine to oral therapy in type 2 diabetes.

METHODS

Pooled patient-level data from 12 prospective, randomized, controlled studies that used insulin glargine in a treat-to-target titration regimen seeking fasting glucose levels ≤5.5 mmol/l (100 mg/dl) were analysed. Baseline characteristics were evaluated by logistic regression models as predictors of reaching a target HbA1c ≤ 7.0% or experiencing confirmed hypoglycaemia. The effect of prior glycaemic control was further explored by analysis of categorical ranges of baseline HbA1c.

RESULTS

Of 2312 participants, 95% completed 24 weeks of treatment. Lower HbA1c at baseline was independently associated with reaching HbA1c target [adjusted odds ratio (OR) for 1% difference: 0.538, p < 0.0001] and also with likelihood of experiencing confirmed hypoglycaemic events (adjusted OR: 0.835, p < 0.0001) at week 24. In an unadjusted analysis by baseline HbA1c range, the strong association between baseline control and attaining target HbA1c was confirmed (75% with baseline HbA1c < 8.0%, 60% with baseline HbA1c ≥ 8.0 and <9.0% and 38% with baseline HbA1c ≥ 9.0% attained HbA1c ≤ 7.0%). The incidence of hypoglycaemia confirmed <3.9 mmol/l (70 mg/dl) was higher in the lower baseline HbA1c ranges but severe hypoglycaemia was infrequent at all baseline HbA1c levels.

CONCLUSIONS

Systematically titrated insulin glargine, added to oral agents, was effective over a wide range of baseline HbA1c. Lower baseline HbA1c was the best clinical predictor of achieving HbA1c ≤ 7.0% and also associated with higher risk of glucose-confirmed hypoglycaemia. Severe hypoglycaemia was infrequent using this treatment approach.

Impact of baseline BMI on glycemic control and weight change with metformin monotherapy in Chinese type 2 diabetes patients: phase IV open-label trial

Background

Differences exist between treatment recommendations regarding the choice of metformin as first-line therapy for type 2 diabetes patients according to body mass index (BMI). This study compared the efficacy of metformin monotherapy among normal-weight, overweight, and obese patients with newly diagnosed type 2 diabetes.

Methods

In this prospective, multicenter, open-label study in China, patients aged 23–77 years were enrolled 1∶1:1 according to baseline BMI: normal-weight (BMI 18.5−23.9 kg/m²; n = 125); overweight (BMI 24.0−27.9 kg/m²; n = 122) or obese (BMI ≥28 kg/m²; n = 124). Extended-release metformin was administered for 16 weeks (500 mg/day, up-titrated weekly to a maximum 2,000 mg/day). The primary efficacy endpoint was the effect of baseline BMI on glycemic control with metformin monotherapy, measured as the change from baseline in glycosylated hemoglobin (HbA_1c) at week 16 compared among BMI groups using ANCOVA. Other endpoints included comparisons of metformin’s effects on fasting plasma glucose (FPG), lipid levels and body weight.

Results

Mean HbA_1c decreases at week 16, adjusted for baseline values, were –1.84%, –1.78% and –1.78% in normal-weight, overweight and obese patients, (P = 0.664); body weight decreased by 2.4%, 3.9% and 3.5%, respectively. FPG levels decreased similarly over time in all BMI groups (P = 0.461) and changes from baseline in high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) did not differ significantly among BMI groups at week 16 (P = 0.143 and 0.451, respectively).

Conclusions

Baseline BMI had no impact on glycemic control, weight change or other efficacy measures with metformin monotherapy. These data suggest that normal-weight type 2 diabetes patients would derive the same benefits from first-line treatment with metformin as overweight and obese patients, and are not at increased risk of excess weight loss.

Trial Registration

ClinicalTrials.gov NCT00778622

In support of an early polypharmacy approach to the treatment of type 2 diabetes

Type 2 diabetes (T2DM) is a multifaceted disease, characterized by hyperglycaemia, resulting from a combination of insulin resistance, impaired incretin action and β-cell dysfunction leading to relative insulin deficiency. Although traditional anti-diabetes agents improve hyperglycaemia, they do so at a cost, which may entail hypoglycemia and increased body weight; exacerbating dyslipidemia, hypertension and components of insulin resistance and metabolic syndrome associated with T2DM-potentially increasing cardiovascular risk. At diagnosis, many patients with T2DM are treated with medical nutritional therapy (MNT) and exercise, then single or multiple oral anti-diabetes agents until treatment failure, when insulin is used. This strategy has been challenged by recommendations for polypharmacy approaches to the treatment of T2DM, as current strategies are unable to improve multiple aspects of the disease, nor are they likely to address underlying pathophysiology. Although the 2009 American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) treatment algorithm recommends a stepwise approach with MNT and metformin, later adding oral agents, incretin-based therapies or insulin, some experts have recommended a more aggressive approach. In his 2008 ADA Banting Lecture, Dr. Ralph DeFronzo recommended early treatment with metformin, TZD and exenatide at initiation of therapy. The authors' of this article recommend an aggressive early polypharmacy approach addressing underlying pathophysiology, including the incretin defect-with MNT and exercise, metformin and an incretin-based therapy and/or basal insulin if glycemic goal is not achieved within 3 months. This approach attempts to modify the disease, aiming for tight glycemic control, weight loss, reduced hypoglycemia, improvements to hypertension, dyslipidemia and insulin resistance-and improved cardiovascular outcomes.

Selecting GLP-1 agonists in the management of type 2 diabetes: differential pharmacology and therapeutic benefits of liraglutide and exenatide

Failure of secretion of the incretin hormone glucagon-like peptide-1 (GLP-1) plays a prominent role in type 2 diabetes, and restoration of GLP-1 action is an important therapeutic objective. Although the short duration of action of GLP-1 renders it unsuited to therapeutic use, 2 long-acting GLP-1 receptor agonists, exenatide and liraglutide, represent a significant advance in treatment. In controlled trials, both produce short-term glucose-lowering effects, with the reduction in hemoglobin A(1c) of up to 1.3%. These responses are often superior to those observed with additional oral agents. However, unlike sulfonylureas, thiazolidinediones, or insulin, all of which lead to significant weight gain, GLP-1 receptor agonists uniquely result in long-term weight loss of around 5 kg, and higher doses may enhance this further. Reduction in blood pressure of 2-7 mm Hg also has been observed. Both drugs produce transient mild gastrointestinal side effects; although mild hypoglycemia can occur, this is usually in combination with other hypoglycemic therapies. However, serious hypoglycemia and acute pancreatitis are rare. The once-daily dosage of liraglutide makes it more convenient than twice-daily dosage of prandial exenatide, and a superior glucose-lowering effect was observed in the only head-to-head comparison reported so far. Besides cost, these considerations currently favor liraglutide over exenatide. Further studies are needed to confirm long-term safety, and most importantly, that short-term benefits translate into long-term reductions of diabetes-related cardiovascular events and other complications.

Treating type 2 diabetes: how safe are current therapeutic agents?

Sulphonylureas (SUs) and biguanides (metformin) are the current mainstays in the treatment of type 2 diabetes (T2DM) and represent the most commonly used oral hypoglycaemic agents (OHAs). In recent years, a variety of new OHAs have become available, including thiazolidinediones, glinides, alpha-glucosidase inhibitors, glucagon-like peptide-1 agonists, amylin analogues and dipeptidyl peptidase-IV inhibitors, providing physicians with a larger therapeutic catalogue than ever before. The traditional drugs metformin and SUs have an established safety profile through long-term use. However, long-term clinical trials and routine use are lacking for many of the new agents, and some potentially serious side effects have been reported with several of these compounds. Until adequate data is obtained, it is difficult to assess the risk-benefit ratio of these agents in relation to the traditional drugs. Until that becomes fully documented, it may be wise to start pharmacologic treatment of patients on an individual basis, weighing the benefits and costs of each medication. Thus, there remains a place for well-established drugs that have a proven safety record and are supported by years of clinical use for the treatment of T2DM.

Metformin therapy and clinical uses

Metformin is now established as a first-line antidiabetic therapy for the management of type 2 diabetes. Its early use in treatment algorithms is supported by lack of weight gain, low risk of hypoglycaemia and its mode of action to counter insulin resistance. The drug's anti-atherosclerotic and cardioprotective effects have recently been confirmed in prospective and retrospective studies, and appear to reflect a collection of glucose-independent effects on the vascular endothelium, suppressant effects on glycation, oxidative stress and formation of adhesion molecules, stimulation of fibrinolysis and favourable effects on the lipid profile. Although avoidance of troublesome gastrointestinal tolerability issues requires careful dose titration, the risk of serious adverse events is considered low provided that contra-indications (especially with respect to renal function) are observed. As many of its actions go beyond glucose lowering, emerging evidence indicates potential benefits in other insulin-resistant states and possibly tumour suppression.

Hypoglycaemia in Type 2 diabetes

The primary cause of hypoglycaemia in Type 2 diabetes is diabetes medication-in particular, those which raise insulin levels independently of blood glucose, such as sulphonylureas (SUs) and exogenous insulin. The risk of hypoglycaemia is increased in older patients, those with longer diabetes duration, lesser insulin reserve and perhaps in the drive for strict glycaemic control. Differing definitions, data collection methods, drug type/regimen and patient populations make comparing rates of hypoglycaemia difficult. It is clear that patients taking insulin have the highest rates of self-reported severe hypoglycaemia (25% in patients who have been taking insulin for > 5 years). SUs are associated with significantly lower rates of severe hypoglycaemia. However, large numbers of patients take SUs in the UK, and it is estimated that each year > 5000 patients will experience a severe event caused by their SU therapy which will require emergency intervention. Hypoglycaemia has substantial clinical impact, in terms of mortality, morbidity and quality of life. The cost implications of severe episodes-both direct hospital costs and indirect costs-are considerable: it is estimated that each hospital admission for severe hypoglycaemia costs around pound1000. Hypoglycaemia and fear of hypoglycaemia limit the ability of current diabetes medications to achieve and maintain optimal levels of glycaemic control. Newer therapies, which focus on the incretin axis, may carry a lower risk of hypoglycaemia. Their use, and more prudent use of older therapies with low risk of hypoglycaemia, may help patients achieve improved glucose control for longer, and reduce the risk of diabetic complications.

Management of Type 2 diabetes: the role of incretin mimetics

Type 2 diabetes is characterised by insulin resistance and progressive beta-cell dysfunction (which leads to hyperglycaemia), the risk of progressive worsening of glycaemic control and an increased risk of both macrovascular and microvascular complications. Existing treatment strategies target deficient insulin secretion and insulin resistance, but do not generally address the underlying progressive beta-cell dysfunction that is common to Type 2 diabetes. Traditionally, Type 2 diabetes is first treated with medical nutrition therapy (reduced food intake and increased physical activity), followed by stepwise addition of oral antidiabetes therapies and, ultimately, exogenous insulin, as required. Unfortunately, these approaches have not been shown to delay the need for additional therapies, nor do they generally prevent or delay the inexorable decline in beta-cell function. Patients with Type 2 diabetes commonly experience deterioration in glycaemic control, and may have substantial weight gain due to the diabetes therapies that contribute to worsening obesity. In addition, insulin-providing therapies, such as sulfonylureas and exogenous insulin, carry the risk of hypoglycaemia, and cannot fully address the complex hormonal irregularities that characterise Type 2 diabetes, including the role of glucagon hypersecretion. New therapeutic approaches are being developed that couple durable glycaemic control with improved control of body weight. These approaches include development of the incretin mimetics, which are a novel class of agents that share several of the glucoregulatory effects of incretin hormones, such as glucagon-like hormone-1. Deficiency of glucagon-like hormone-1 secretion is known to be present in those with abnormal glucose tolerance. Agents that manipulate the physiological actions of incretin hormones, such as glucagon-like hormone-1, may significantly benefit patients with Type 2 diabetes.

Incretin mimetics and dipeptidyl peptidase-IV inhibitors: a review of emerging therapies for type 2 diabetes

Type 2 diabetes is thought to develop as a result of progressive beta-cell dysfunction in the setting of insulin resistance, leading to increased risks of microvascular and macrovascular complications. Type 2 diabetes is currently treated with diet and exercise, followed by oral drug therapy, and finally exogenous insulin. While this approach is known to improve glycemic control, none of the currently available therapies significantly improve beta-cell function. In addition, this approach does not address defects in hormonal secretion thought to play key roles in the pathophysiology of type 2 diabetes. Type 2 diabetes is characterized by excess glucagon secretion and insufficient secretion of the hormone amylin from the pancreatic beta-cell. In addition, individuals with type 2 diabetes demonstrate insufficient secretion of the incretin hormone glucagon-like peptide-1 (GLP-1). Novel therapies that leverage the so-called "incretin effect" of GLP-1 (including the incretin mimetics and dipeptidyl peptidase-IV (DPP-IV) inhibitors) are being actively developed for the management of type 2 diabetes. Incretin mimetics are either derivatives of GLP-1, modified to resist proteolysis, or are novel peptides that share glucoregulatory functions with GLP-1 and are naturally resistant to proteolysis. DPP-IV inhibitors enhance the concentration of endogenous GLP-1 by limiting proteolysis of native GLP-1. With the approval of exenatide- the first "incretin mimetic"-treatment of type 2 diabetes will no doubt be changed. An understanding of the effects of these compounds will be needed to enhance the clinical approach to diabetes treatment.

New insights into glucose regulation

This review article describes the regulation of glucose homeostasis in subjects with and without diabetes based on the emergence of new information and discusses modes of action, attributes, and limitations of current diabetes therapies. In normal physiology, glucose homeostasis is tightly controlled by the interaction of pancreatic and gut hormones. Since the 1920s, diabetes has been viewed as a disease caused by deficient secretion of insulin, resulting in reduced glucose uptake and subsequent hyperglycemia. The discovery in the 1950s of the pancreatic hormone glucagon, which opposes insulin by increasing glucose appearance in the circulation, resulted in a bihormonal model of glucose homeostasis. More recently, with the discovery of the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) in the 1970s and the pancreatic hormone amylin in the 1980s, it is now understood that several organs and hormones play roles in maintaining glucose homeostasis. Therapies for diabetes have focused on compensation for deficient insulin action through stimulation of insulin secretion, administration of insulin itself, reduction of peripheral insulin resistance, or decreased glucose absorption from the intestine. The discoveries of amylin and GLP-1 have furthered our understanding of the abnormalities involved in diabetes, enabling the development of additional therapeutic options.

Metformin monotherapy for type 2 diabetes mellitus

BACKGROUND

Metformin is an anti-hyperglycaemic agent used for the treatment of type 2 diabetes mellitus. Type 2 diabetes may present long-term complications: micro- (retinopathy, nephropathy and neuropathy) and macrovascular (stroke, myocardial infarction and peripheral vascular disease). Two meta-analyses have been published before, although only secondary outcomes were assessed.

OBJECTIVES

To assess the effects of metformin monotherapy on mortality, morbidity, quality of life, glycaemic control, body weight, lipid levels, blood pressure, insulinaemia, and albuminuria in patients with type 2 diabetes mellitus.

SEARCH STRATEGY

Studies were obtained from computerised searches of multiple electronic databases and hand searches of reference lists of relevant trials identified. Date of last search: September 2003.

SELECTION CRITERIA

Trials fulfilling the following inclusion criteria: Diabetes mellitus type 2, metformin versus any other oral intervention, assessment of relevant clinical outcome measures, use of random allocation.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted data, using a standard data extraction form. Data were summarised under a random effects model. Dichotomous data were expressed as relative risk. We calculated the risk difference (RD), and the Number Needed to Treat, when it was possible. We collected data of mean and standard deviation from changes to baseline. However many trials reported end point data. This limitation lead to the expression of the results as standardised mean differences (SMD) and an overall SMD was calculated. Heterogeneity was tested for using the Z score and the I-squared statistic. Subgroup, sensitivity analysis and meta-regression were used to explore heterogeneity.

MAIN RESULTS

We included for analysis 29 trials with 37 arms (5259 participants), comparing metformin (37 arms and 2007 participants) with sulphonylureas (13 and 1167), placebo (12 and 702), diet (three and 493), thiazolidinediones (three and 132), insulin (two and 439), meglitinides (two and 208), and glucosidase inhibitors (two and 111). Nine studies reported data on primary outcomes. Obese patients allocated to intensive blood glucose control with metformin showed a greater benefit than chlorpropamide, glibenclamide, or insulin for any diabetes-related outcomes (P = 0.009), and for all-cause mortality (P = 0.03). Obese participants assigned to intensive blood glucose control with metformin showed a greater benefit than overweight patients on conventional treatment for any diabetes-related outcomes (P = 0.004), diabetes-related death (P = 0.03), all-cause mortality (P = 0.01), and myocardial infarction (P = 0.02). Patients assigned to metformin monotherapy showed a significant benefit for glycaemia control, weight, dyslipidaemia, and diastolic blood pressure. Metformin presents a strong benefit for HbA1c when compared with placebo and diet; and a moderated benefit for: glycaemia control, LDL cholesterol, and BMI or weight when compared with sulphonylureas.

AUTHORS' CONCLUSIONS

Metformin may be the first therapeutic option in the diabetes mellitus type 2 with overweight or obesity, as it may prevent some vascular complications, and mortality. Metformin produces beneficial changes in glycaemia control, and moderated in weight, lipids, insulinaemia and diastolic blood pressure. Sulphonylureas, alpha-glucosidase inhibitors, thiazolidinediones, meglitinides, insulin, and diet fail to show more benefit for glycaemia control, body weight, or lipids, than metformin.

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.

Tolerability Profile of Metformin/Glibenclamide Combination Tablets (Glucovance??)

It is important to manage blood glucose intensively in patients with type 2 diabetes mellitus in order to reduce the risk of long-term complications. Oral combination therapy that addresses insulin resistance and beta-cell dysfunction is a proven means of improving glycaemic control when monotherapy becomes insufficiently effective. Metformin/glibenclamide (glyburide) combination tablets were developed to provide a means of applying this strategy while minimising polypharmacy. This review examines the tolerability profile of this treatment from four double-blind, randomised clinical trials in a total of 2342 type 2 diabetic patients with hyperglycaemia despite treatment with diet and exercise, a sulphonylurea or metformin. Treatment with combination tablets was associated with markedly superior blood glucose control, at lower doses of metformin and glibenclamide, compared with monotherapies. The incidence of symptoms of hypoglycaemia varied between dosages and trials, though the incidence of severe or biochemically confirmed hypoglycaemia or withdrawals from clinical trials for this reason was consistently low and comparable with glibenclamide alone. No patient required third-party assistance for hypoglycaemia. Significantly fewer diet-failed patients receiving low-dose combination tablets reported gastrointestinal adverse effects compared with metformin alone, with a comparable incidence between metformin and combination tablets in post-monotherapy studies. The incidence of other adverse events, including serious adverse events, was similar for combination tablets and monotherapies. The lower doses of metformin and glibenclamide with the combination tablet approach, and the design of the combination tablets themselves, may underlie the beneficial tolerability profile of this treatment.

Towards Single-Tablet Therapy for Type 2 Diabetes Mellitus

Type 2 diabetes mellitus emerges as a result of multiple pathophysiologic changes. If the pharmacotherapy of type 2 diabetes should be tailored to the underlying pathophysiology, it would be necessary to use a combination of agents with complementary mechanisms of action. The two principal defects in type 2 diabetes are insulin deficiency and insulin resistance. Therefore, combining an insulin-providing agent with an insulin-sensitizing agent will augment the efficacy of current antihyperglycemic agents. This is the rationale for the development and marketing of sulfonylurea/metformin combination tablets.Randomized double-blind clinical trials have shown the safety and efficacy of these fixed combination tablets in both drug-naive individuals as well as in those individuals not achieving glycemic goals on sulfonylurea or metformin monotherapy. These studies have also shown that these tablets may be associated with better postprandial glycemic control compared with monotherapy. However, the risk of hypoglycemia is increased with the use of combination tablets, especially in drug-naive individuals with baseline glycosylated hemoglobins of <8.0%. Combining two insulin-sensitizing agents that have different mechanisms of action and that target different biochemical pathways, would also enhance efficacy. This can be accomplished by combining metformin with rosiglitazone or pioglitazone. The recently developed fixed formulation tablet of metformin/rosiglitazone is available for use as second-line therapy in individuals who have not reached their glycemic goals while on metformin. The advantages of combining several agents in one tablet include convenience and enhanced adherence to therapy. The main disadvantage is the loss of administration flexibility.

Glyburide/metformin tablets: a new therapeutic option for the management of Type 2 diabetes

Oral antidiabetic combination therapy is a proven means of establishing glycaemic control in the hyperglycaemic, Type 2 diabetic patient, but co-administering two oral antidiabetic agents separately may hinder compliance with therapy. A new single-tablet of glyburide/metformin combination therapy (Glucovance), Bristol-Myers Squibb, Inc.) has recently been developed, which addresses the primary defects of Type 2 diabetes: beta-cell dysfunction and insulin resistance. The glyburide/metformin tablet, taken with meals, is designed to optimise the absorption of glyburide and to address the postprandial glucose rise. Glyburide/metformin tablets are more effective in controlling fasting and postprandial glycaemia than its component monotherapies, at lower doses of metformin and glyburide compared with monotherapy because of the synergy between its glyburide and metformin components. Moreover, a double-blind study showed that glyburide/metformin tablets are more effective than a free combination of glyburide co-administered with metformin in controlling postprandial glucose. Retrospective analyses suggested that glyburide/metformin tablets control glycated haemoglobin (A1C) more effectively than a free combination of glyburide co-administered with metformin, at lower mean doses of glyburide and metformin. The incidence of side effects is lower than separate component therapy for any given A1C. Glyburide/metformin tablets are an effective option for optimising the control of blood glucose in Type 2 diabetic patients and appear to enhance adherence to therapy.