UKPDS 28: a randomized trial of efficacy of early addition of metformin in sulfonylurea-treated type 2 diabetes. U.K. Prospective Diabetes Study Group

Improved glycemic control without weight gain using triple therapy in type 2 diabetes

OBJECTIVE

To evaluate the safety and effectiveness of triple therapy using insulin, metformin, and a thiazolidinedione following a course of dual therapy using insulin and metformin or insulin and a thiazolidinedione in type 2 diabetes.

RESEARCH DESIGN AND METHODS

Twenty-eight type 2 diabetic subjects using insulin monotherapy (baseline HbA(lc) level 8.5%) who had been randomly assigned to insulin (INS) and metformin (MET) (INS + MET, n = 14) or INS and the thiazolidinedione troglitazone (TGZ) (INS + TGZ, n = 14) (dual therapy) for 4 months were given INS, MET, and TGZ (triple therapy: INS + MET, add TGZ; or INS + TGZ, add MET) for another 4 months. The INS dose was not increased.

RESULTS

HbA(1c) levels decreased in both groups during dual therapy and improved further during triple therapy (INS + MET 7.0 +/- 0.8, INS + TGZ 6.2 +/- 0.8, P < 0.0001; INS + MET, add TGZ 6.1 +/- 0.4%, P < 0.001; INS + TGZ, add MET 5.8 +/- 0.6%, P < 0.05; and INS + TGZ vs. INS + MET, P = 0.02). Significant reductions in total daily insulin dose occurred in the INS + TGZ (-14.1 units, P < 0.0001), INS + TGZ add MET (-13.7 units, P < 0.01), and the INS + MET add TGZ groups (-17.3 units, P < 0.003), but not in the INS + MET group (-3.2 units) (INS + TGZ vs. INS + MET P < 0.05). Subjects in the INS + TGZ group experienced significant weight gain (4.4 +/- 2.7 kg, P < 0.0005). No weight gain occurred in the INS + MET, INS + MET add TGZ, and INS + TGZ add MET groups.

CONCLUSIONS

Triple therapy using INS, MET, and TGZ resulted in lower HbA(lc) levels and total daily insulin dose than during dual therapy. The use of triple therapy resulted in 100% of subjects achieving an HbA(lc) <7.0%, while decreasing the dose of INS. Weight gain was avoided when MET therapy preceded the addition of TGZ therapy. The addition of TGZ resulted in the greatest reductions in HbA(lc) levels and insulin dose. Triple therapy using INS, MET, and a thiazolidinedione (such as TGZ) can be a safe and effective treatment in type 2 diabetes.

The prevention of type 2 diabetes mellitus: recent advances

Diabetes is a major public health problem that is approaching epidemic proportions globally. There is an urgent need for strategies to curb the rising prevalence of this disease, and prevention appears a logical approach. Lifestyle modifications with weight loss and moderate exercise can reduce the incidence of diabetes by >50% in patients with impaired glucose tolerance (IGT). The use of metformin, acarbose and other agents have been shown in randomized prospective trials to prevent type 2 diabetes in high-risk subjects with IGT. Other pharmacological interventions are currently being examined in large prospective studies. It is likely that one or a combination of these approaches could make diabetes prevention a reality in the near future.

The effect of metformin on blood pressure, plasma cholesterol and triglycerides in type 2 diabetes mellitus: a systematic review

BACKGROUND

The UKPDS 34 showed that intensive treatment with metformin significantly reduces macrovascular end-points and mortality in individuals with newly diagnosed type 2 diabetes compared with intensive treatment with insulin or sulphonylurea derivatives, despite similar glycaemic control. How this should be explained is as yet unclear. We hypothesized that metformin may have a glucose-lowering independent effect on blood pressure and lipid profile. In order to test this hypothesis we systematically reviewed the literature and pooled the data obtained in a meta-analysis.

METHODS

Included were randomized-controlled trials in patients with type 2 diabetes mellitus and metformin treatment lasting at least 6 weeks. To identify all eligible trials we conducted electronic searches using the bibliographic databases Medline and Embase, contacted the manufacturer and checked obtained publications for cross-references.

RESULTS

Forty-one studies (3074 patients) provided data on blood pressure and/or lipid profile. When compared with control treatment, metformin associated effects on systolic and diastolic blood pressure and HDL cholesterol were small and statistically not significant [-1.09 mmHg 95% confidence interval (-3.01-0.82), P = 0.30; -0.97 (-2.15-0.21) mmHg, P = 0.11 and +0.01 (-0.02-0.03) mmol L(-1), P = 0.50, respectively]. Compared with control treatment, however, metformin decreased plasma triglycerides, total cholesterol and LDL cholesterol significantly [-0.13 (-0.21--0.04) mmol L(-1), P = 0.003; -0.26 (-0.34--0.18) mmol L(-1), P < 0.0001 and -0.22 (-0.31--0.13) mmol L(-1), P < 0.00001, respectively]. We found no indications for publication bias. Of note, glycaemic control as assessed by HbA1c was better with metformin than with control treatment [-0.74 (-0.84--0.65) percentage point; P < 0.00001]. When studies were subdivided into tertiles according to increasing difference in glycaemic control between metformin and control treatment, it appeared that in case of near similar glycaemic control metformin had no effect versus control treatment on triglycerides, whereas still there was a significant effect on total and LDL cholesterol.

CONCLUSIONS

This meta-analysis of randomized-controlled clinical trials suggests that metformin has no intrinsic effect on blood pressure, HDL cholesterol and triglycerides in patients with type 2 diabetes. This drug, however, independent of its effect on glycaemia, reduces total and LDL cholesterol significantly, but the reductions in these variables are relatively small.

Metformin hydrochloride in the treatment of type 2 diabetes mellitus: a clinical review with a focus on dual therapy

BACKGROUND

Type 2 diabetes mellitus typically involves abnormal beta-cell function that results in relative insulin deficiency, insulin resistance accompanied by decreased glucose transport into muscle and fat cells, and increased hepatic glucose output, all of which contribute to hyperglycemia.

OBJECTIVE

This review examines the pharmacology, pharmacokinetics, drug-interaction potential, adverse effects, and dosing guidelines for metformin hydrochloride, a biguanide agent for the treatment of type 2 diabetes. Clinical trial data are reviewed, including efficacy and tolerability information, with a focus on studies of dual metformin therapy (metformin plus another oral agent or insulin) published from 1998 to the present. Pharmacoeconomic considerations are also discussed.

METHODS

Primary research and review articles were identified through a search of MEDLINE (1966-May 2003) and International Pharmaceutical Abstracts (1970-May 2003) using the terms metformin and/or Glucophage. Web of Science (1995-May 2003) was used to search for additional abstracts. The package inserts for metformin and metformin combination products were consulted. All identified articles and abstracts were assessed for relevance, and all relevant information was included. Priority was given to the primary medical literature and clinical trial reports.

RESULTS

Metformin is the only currently available oral antidiabetic/hypoglycemic agent that acts predominantly by inhibiting hepatic glucose release. Because patients with type 2 diabetes often have excess hepatic glucose output, use of metformin is effective in lowering glycosylated hemoglobin (HbA1c) by 1 to 2 percentage points when used as monotherapy or in combination with other blood glucose-lowering agents or insulin. Other metabolic variables (eg, dyslipidemia, fibrinolysis) may be improved with the use of metformin. Body weight is often maintained or slightly reduced from baseline. Metformin is well tolerated and is associated with few clinically deleterious adverse events. The most important and potentially life-threatening adverse event associated with its use is lactic acidosis, which occurs very rarely.

CONCLUSIONS

Metformin has multiple benefits in patients with type 2 diabetes. It can effectively lower HbA1c values, positively affect lipid profiles, and improve vascular and hemodynamic indices. Adverse effects are generally tolerable and self-limiting. The availability of products combining metformin with a sulfonylurea or rosiglitazone has expanded the array of therapies for the management of type 2 diabetes.

Clinical inertia in the management of Type 2 diabetes metabolic risk factors

AIMS

Delays in the initiation and intensification of medical therapy may be one reason patients with diabetes do not reach evidence-based goals for metabolic control. We assessed intensification of medical therapy over time, comparing the management of hyperglycaemia, hypertension, and hyperlipidaemia.

METHODS

Prospective cohort study of 598 adults with Type 2 diabetes receiving primary care in an academic medical centre from May 1997 to April 1999. We assessed whether patients failing to achieve standard treatment goals for haemoglobin A1c (HbA1c), systolic blood pressure (SBP), or low density lipoprotein (LDL) cholesterol when last measured during 12 months (Year 1, 5/97-4/98) had increases in their corresponding medical regimen during the following 12 months (Year 2, 5/98-4/99).

RESULTS

Among untreated patients in Year 1, seven of 12 (58%) of those above goal for HbA1c were initiated on medical therapy in Year 2, compared with 16 of 48 (34%) above SBP goal (P=0.02) and 26 of 115 (23%) above LDL cholesterol goal (P=0.02). Among patients on therapy and above goal, 124 of 244 (51%) patients with elevated HbA1c had their regimen increased in Year 2, compared with 85 of 282 (30%) with elevated SBP (P<0.001) and 22 of 79 (30%) with elevated LDL cholesterol (P<0.001). From Year 1 to Year 2 there was a decline in the overall proportion of patients above goal for LDL cholesterol (from 58% to 45%, P=0.002) but not for HbA1c or blood pressure.

CONCLUSIONS

Greater initiation and intensification of pharmaceutical therapy, particularly for elevated blood pressure or cholesterol, may represent a specific opportunity to improve metabolic control in Type 2 diabetes.

Cardiovascular disease in patients who have diabetes

Although cardiovascular disease continues to be the major cause of morbidity and mortality in diabetes, the understanding that multiple risk factor intervention is the cornerstone of diabetes management is leading to significant benefits for patients. Aggressive goal setting for modifiable cardiovascular risk factors that cluster in patients with diabetes, such as dyslipidemia, hypertension, and a procoagulant state, and judicious selection of efficacious therapies have been shown to produce significant reductions in cardiovascular events, and in some cases mortality, in controlled clinical trials. Although effective control of hyperglycemia per se has at most modest impact, the choice and application of antihyperglycemic therapies add to the benefit. In addition, newer agents and early intervention in prediabetic and diabetic individuals hold promise for even greater success in the prevention of this important complication of diabetes.

A Comparison of Agents Used to Manage Type 2 Diabetes Mellitus

In patients with type 2 diabetes mellitus, the traditional method of initiating therapy with a sulfonylurea and increasing the dosage until maximum levels are reached before adding an insulin-sensitizing agent has persisted and should be re-evaluated. Similarly, the current practice of starting therapy with one agent and increasing to maximum dosage before adding a second agent, rather than starting with combination therapy, also needs to be addressed. There is much evidence to suggest that initiating therapy with lower doses of two agents that have complementary effects can increase the overall efficacy and decrease the incidence of adverse effects. Clearly, there is a need for a paradigm shift away from the traditional approach of therapy using insulin secretagogues to a more pathophysiologic approach using an insulin-sensitizing agent, such as the thiazolidinediones. The thiazolidinediones have been shown to reduce insulin resistance, improve the ability of beta-cells to produce insulin, and decrease cardiac risk factors. By reducing insulin resistance, improving glycemic control, and preserving beta-cell function with a thiazolidinedione early in the course of therapy, it is likely that durable glycemic control will be achieved and both microvascular and macrovascular complications may be reduced. Furthermore, early use of an insulin-sensitizing agent either alone or incombination is expected to improve both acute and long-term outcomes in patients with type 2 diabetes.

Prevention and treatment of type 2 diabetes mellitus in children, with special emphasis on American Indian and Alaska Native children. American Academy of Pediatrics Committee on Native American Child Health

The emergence of type 2 diabetes mellitus in the American Indian/Alaska Native pediatric population presents a new challenge for pediatricians and other health care professionals. This chronic disease requires preventive efforts, early diagnosis, and collaborative care of the patient and family within the context of a medical home.

Improving glycaemic control in patients with Type 2 diabetes mellitus without insulin therapy

AIMS

In general practice at least 30% of those with Type 2 diabetes do not achieve good glycaemic control. We studied the effect of improving oral glucose-lowering medication in a primary care setting in patients treated with oral hypoglycaemic agents without satisfactory glycaemic control.

METHODS

We provided flowcharts to general practitioners and outreach visits by trained facilitators, who checked adherence to the protocol. Fifty-two Dutch general practices with 2140 Type 2 diabetes mellitus (DM) patients recruited 288 patients < or = 75 years old inadequately controlled (HbA1c >7%) by diet or oral medication. Outcome measures were decrease of HbA1c, number of patients with HbA1c < or = 7%, and non-compliance rate.

RESULTS

After a mean of 3.3 consultations over 14 weeks, 209 patients were following the protocol fully with a reduction in HbA1c from 8.7% to 6.7% (P<0.001). One hundred and fifty-eight patients (55%) achieved HbA1c < or =7%, and 51 (18%) persisted with HbA1c >7% unless fasting blood glucose < or =7 mmol/l (n=18) or a maximum of medication (n=33). Seventy-nine patients (27%) did not adhere to the protocol, mostly due to loss of motivation and non-attendance.

CONCLUSIONS

A simple flowchart and relatively little support by trained facilitators results in improved glycaemic control.

Combination treatment with metformin and glibenclamide versus single-drug therapies in type 2 diabetes mellitus: a randomized, double-blind, comparative study

To compare efficacy and tolerability of combination treatment with metformin and sulfonylurea with each of these drugs alone in the treatment of type 2 diabetes, 88 type 2 diabetic subjects (hemoglobin A1c [HbA1c] levels, 8.0%+/-1.0%; age, 57.3+/-7.1 years; body mass index [BMI]. 27.0+/-2.6 kg/m2; diabetes duration, 9.8+/-8.2 years; means +/- SD) were randomly assigned to double-blind treatment with metformin (500 to 3,000 mg/d), glibenclamide (5 to 15 mg/d), or their combination (metformin 400 to 2,400 mg/d + glibenclamide 2.5 to 15 mg/d) for 6 months. Thereafter, groups were crossed over for the following 6 months. Thus, each patient received metformin or glibenclamide alone, and the combination treatment. Doses were titrated to obtain HbA1c levels < or = 6.0% and fasting plasma glucose levels less than 140 mg/dL. Eighty patients concluded both treatment periods and were included in the analysis of treatment efficacy. In patients receiving metformin or glibenclamide alone, the maximal dose was reached in 21 and 25 patients, respectively; 8 and 15 of these subjects, respectively, required the maximal dose when they were on the combination treatment. During the study, 4 (10.0%) subjects receiving metformin, 7 (17.1%) receiving glibenclamide, and 31 (39.2%) receiving the combination treatment reached HbA1c levels < or = 6.0%. Moreover, when efficacy of the combination treatment on glycemic control was compared with that of single-drug therapies in each individual patient, the combination was significantly more effective than either metformin or glibenclamide (HbA1c after treatment, 6.1%+/-1.1% v 7.3%+/-1.4%, and 6.5%+/-0.7% v 7.6%+/-1.5%, respectively, both P<.0001). In conclusion, combination treatment with metformin and sulfonylurea is more effective than these drugs alone in improving glycemic control in type 2 diabetes, while also allowing a reduction of the dosage of each drug.

Pharmacotherapy of diabetes mellitus: implications for the prevention and treatment of cardiovascular disease

Diabetes mellitus in adults is associated with an increased risk of premature vascular disease and a higher mortality rate. The presence of other risk factors, often seen in diabetic patients, such as systemic hypertension, augments the rate of vascular diseases. Evidence is growing that tight control of hyperglycemia using insulin and/or oral hypoglycemic agents will modify this risk. More aggressive control of concomitant hypertension and/or hyperlipidemia is also required. Diabetic patients who have myocardial infarctions do worse than nondiabetic patients. Various strategies to improve outcomes include the use of tight blood glucose control, and various coronary interventions are currently under clinical study.

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

BACKGROUND

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

OBJECTIVES

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

SEARCH STRATEGY

A search was performed of the Cochrane Controlled Trials Register and the Database of Abstracts of Reviews of Effectiveness (up to 4/2000), Medline (up to 11/2000), Embase (up to 11/2000), Oldmedline, and Reactions (up to 5/2000), in order to identify all studies of metformin treatment from 1966 to November 2000. The Cumulated Index Medicus was used to search relevant articles from 1959 to 1965. The search was augmented by scanning references of identified articles, and by contacting principal investigators. Date of latest search: November 2000.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

Pooled data from 176 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 35,619 patient-years of metformin use or in 30,002 patients-years in the non-metformin group. Using Poisson statistics with 95% confidence intervals the upper limit for the true incidence of metformin-associated lactic acidosis was 8.4 cases per 100,000 patient-years, and the upper limit for the true incidence of lactic acidosis in the non-metformin group was 9 cases per 100,000 patient-years. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to placebo or other non-biguanide therapies. The mean lactate levels were slightly lower for metformin treatment compared to phenformin (WMD -0.75 mmol/L, 95% CI -0.86 to -0.15).

REVIEWER'S CONCLUSIONS

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

The status of diabetes control in Asia--a cross-sectional survey of 24 317 patients with diabetes mellitus in 1998

AIMS

To establish the status of diabetes control in Asia, the Diabcare-Asia 198 study collected data from 230 diabetes centres in Bangladesh, People's Republic of China, India, Indonesia, Malaysia, Philippines, Singapore, South Korea, Sri Lanka, Taiwan, Thailand and Vietnam from March to December 1998.

METHODS

Data were obtained either by patient interview during the enrolment visit or by reviewing medical records for the most recent laboratory assessment and clinical examinations. Blood samples were also collected during patients'. visits for central assessments of HbA1c (normal range 4.7-6.4%).

RESULTS

The mean of centrally measured HbA1c was 8.6 +/- 2.0% for 18 211 patients (82% of the analysis population). Of the patients with central HbA1c measurements, the majority (55%) had values exceeding 8%, indicative of poor glycaemic control. The prevalence of retinopathy, microalbuminuria and neuropathy was also higher in the group of patients with higher HbA1c. Based on the findings from central HbA1c measurements and reported local HbA1c assessments, it also appears that more patients with poor glycaemic control did not have access to glycated haemoglobin measurements. Mean HbA1c of thediabetic populations in Bangladesh, Indonesia, Korea, Malaysia and Taiwan were significantly lower (all P = 0.0001, except P = 0.0007 for Malaysia), while that of China, India, Philippines and Vietnam was significantly higher (all P = 0.0001) than the grand mean.

CONCLUSIONS

In our study population of the Asian diabetes patients treated at diabetes centres, more than half were not well controlled. The prevalence of diabetic microvascular complications was higher in the group of patients with higher HbA1c. Further therapeutic actions to improve glycaemic control are required to prevent chronic diabetic complications.

Decreased mortality associated with the use of metformin compared with sulfonylurea monotherapy in type 2 diabetes

OBJECTIVE

The aim of this study was to examine the relationship between use of metformin and sulfonylurea and mortality in new users of these agents.

RESEARCH DESIGN AND METHODS

Saskatchewan Health databases were used to examine population-based mortality rates for new users of oral antidiabetic agents. Individuals with prescriptions for sulfonylurea or metformin in 1991-1996 and no use in the year prior were identified as new users. Prescription records were prospectively followed for 1-9 years; subjects with any insulin use were excluded. Causes of death were identified based on ICD-9 codes in an electronic vital statistics database. Multivariate logistic regression and survival analyses were used to assess the differences in mortality between drug cohorts, after adjusting for potential confounding variables.

RESULTS

The total study sample comprised 12,272 new users of oral antidiabetic agents; the average length of follow-up was 5.1 (SD 2.2) years. In subjects with at least 1 year of drug exposure and no insulin use, mortality rates were 750/3,033 (24.7%) for those receiving sulfonylurea monotherapy, 159/1,150 (13.8%) for those receiving metformin monotherapy, and 635/4,683 (13.6%) for those receiving combination therapy over an average 5.1 (SD 2.2) years of follow-up. The adjusted odds ratio (OR) for all-cause mortality for metformin monotherapy was 0.60 (95% CI 0.49-0.74) compared with sulfonylurea monotherapy. Sulfonylurea plus metformin combination therapy was also associated with reduced all-cause mortality (OR 0.66, 95% CI 0.58-0.75). Reduced cardiovascular-related mortality rates were also observed in metformin users compared with sulfonylurea monotherapy users.

CONCLUSIONS

Metformin therapy, alone or in combination with sulfonylurea, was associated with reduced all-cause and cardiovascular mortality compared with sulfonylurea monotherapy among new users of these agents.

Troglitazone: the discovery and development of a novel therapy for the treatment of Type 2 diabetes mellitus

Prior to the introduction of troglitazone, it had been more than 30 years since the last significant improvement in antidiabetic therapy. In view of the pressing need for more effective oral agents for the treatment of Type 2 diabetes mellitus, troglitazone was granted priority review by the FDA and was launched in the USA in 1997. The first of the thiazolidinedione insulin sensitizing agents, troglitazone was quickly followed by rosiglitazone and pioglitazone. The glitazones proved to be effective not only in lowering blood glucose, but also to have beneficial effects on cardiovascular risk. Troglitazone was subsequently withdrawn because of concerns about hepatotoxicity, which appears to be less of a problem with rosiglitazone and pioglitazone. Recent insights into the molecular mechanism of action of the glitazones, which are ligands for the peroxisome proliferator-activated receptors, open the prospect of designing more effective, selective and safer antidiabetic agents. This document will review the history of troglitazone from discovery through clinical development.

Oral combination therapy for type 2 diabetes

For patients with type 2 diabetes, oral monotherapy may be initially effective for controlling blood glucose, but it is associated with a high secondary failure rate. (Primary failure is frequent only in patients with high baseline blood glucose at the time of beginning monotherapy, whereas secondary failure is to be expected in the course of the disease.) The different classes of oral agents used to treat type 2 diabetes have complementary mechanisms of action, and their use in combination often results in blood glucose reductions that are significantly greater than those that can be obtained with maximal doses of any single drug. A wide range of combinations (e.g. sulfonylurea plus metformin, a thiazolidinedione, or acarbose; metformin plus a thiazolidinedione or acarbose) have been used effectively to achieve glycemic control in patients in whom oral monotherapy has failed. The high secondary failure rates for oral monotherapy - and, moreover, the high primary failure rate in patients with very high blood glucose at diagnosis - coupled with the effectiveness of combination treatment, support the suggestion that multiple-drug regimens be considered for initial pharmacologic treatment in patients with symptomatic type 2 diabetes whose blood glucose is not controlled by diet alone.

[Treatment of diabetes mellitus: general goals, and clinical practice management]

Diabetes mellitus is associated with a marked increased of cardiovascular events. The treatment strategy of diabetes has to be based on the knowledge of its pathophysiology. Thus, insulin is essential for treatment of type 1 diabetic patients because there is a defect in insulin secretion. However, treatment of type 2 diabetic patients is more complex because a defect in both insulin secretion and insulin action exists. Therefore, the treatment selection will depend on the stage of the disease and the individual characteristics of the patient. This article examines the general goals of the treatment and reviews the management of type 2 diabetes.

Improved glycaemic control with metformin-glibenclamide combined tablet therapy (Glucovance) in Type 2 diabetic patients inadequately controlled on metformin

AIMS

To evaluate the efficacy and safety of two dosage strengths of a single-tablet metformin-glibenclamide (glyburide) combination, compared with the respective monotherapies, in patients with Type 2 diabetes mellitus (DM) inadequately controlled by metformin monotherapy.

METHODS

In this 16-week, double-blind, multicentre, parallel-group trial, 411 patients were randomized to receive metformin 500 mg, glibenclamide 5 mg, metformin-glibenclamide 500 mg/2.5 mg or metformin-glibenclamide 500 mg/5 mg, titrated with the intention to achieve fasting plasma glucose (FPG) < or = 7 mmol/l.

RESULTS

Decreases in glycated haemoglobin (HbA1c) and FPG were greater (P < 0.05) for metformin-glibenclamide 500 mg/2.5 mg (-1.20% and -2.62 mmol/l) and 500 mg/5 mg (-0.91% and -2.34 mmol/l), compared with metformin (-0.19% and -0.57 mmol/l) or glibenclamide (-0.33% and -0.73 mmol/l). HbA1c < 7% was achieved by 75% and 64% of patients receiving metformin-glibenclamide 500 mg/2.5 mg and 500 mg/5 mg, respectively, compared with 42% for glibenclamide and 38% for metformin (P = 0.001). These benefits were achieved at lower mean doses of metformin or glibenclamide with metformin-glibenclamide 500 mg/2.5 mg and 500 mg/5 mg (1225 mg/6.1 mg and 1170 mg/11.7 mg) than with glibenclamide (13.4 mg) or metformin (1660 mg). Treatment-related serious adverse events occurred in two patients receiving glibenclamide. Plasma lipid profiles were unaffected and mean changes in body weight were < or = 1.0 kg.

CONCLUSIONS

Intensive management of Type 2 DM with a new metformin-glibenclamide combination tablet improved glycaemic control and facilitated the attainment of glycaemic targets at lower doses of metformin or glibenclamide compared with the respective monotherapies, without compromising tolerability.

Options for pharmacological management of obesity in patients treated with atypical antipsychotics

Obesity is associated with considerable morbidity and decreased life expectancy. Weight gain is a commonly encountered problem associated with antipsychotic treatment. We reviewed the literature regarding the mechanisms of weight gain in response to these agents and eight substances implicated as potential obesity prevention or treatment: orlistat, sibutramine, fluoxetine, topiramate, amantadine, nizatidine and cimetidine, and metformin. Weight gain in response to antipsychotic treatment may be mediated through serotonergic, dopaminergic, adrenergic, cholinergic, histaminergic and glutaminergic receptors. Sex hormone dysregulation and altered insulin sensitivity have also been implicated. Two compounds, orlistat and sibutramine, have been shown to help prevent weight gain following a hypocaloric diet, but orlistat requires compliance with a fat-reduced diet, and sibutramine is unsuitable for patients taking serotonergic agents. The weight reducing effect of fluoxetine, even in conjunction with a hypocaloric diet, is only transient. Topiramate, amantadine and metformin may have adverse side-effects potentially outweighing the weight reducing potential. The effectiveness of cimetidine and nizatedine remains unclear. The hazards of these agents in a psychiatric population are discussed. It is concluded that the current evidence does not support the general use of pharmacological interventions for overweight patients treated with antipsychotic medication, although individually selected patients may benefit.

Adherence to oral antidiabetic therapy in a managed care organization: a comparison of monotherapy, combination therapy, and fixed-dose combination therapy

BACKGROUND

Although medication adherence is one of the most important aspects of the management of diabetes mellitus, low rates of adherence have been documented.

OBJECTIVE

This study sought to examine medication adherence among patients with diabetes mellitus in a managed care organization who were receiving antidiabetic monotherapy (metformin or glyburide), combination therapy (metformin and glyburide), or fixed-dose combination therapy (glyburide/metformin).

METHODS

Medication adherence was evaluated through a retrospective database analysis of pharmacy claims. The adherence rate was defined as the sum of the days' supply of oral antidiabetic medication obtained by the patient during the follow-up period divided by the total number of days in the designated follow-up period (180 days). Health plan members were included in the analysis if they had an index pharmacy claim for an oral antidiabetic medication between August 1 and December 31, 2000, were continuously enrolled in the health plan, and were aged > or =18 years. A 6-month pre-index period was used to classify patients as newly treated or previously treated. Patients were grouped according to their medication-use patterns.

RESULTS

After adjustment for potential confounding factors, including overall medication burden at index, there were no significant differences in adherence rates among 6502 newly treated patients receiving monotherapy, combination therapy, or fixed-dose combination therapy. Among the 1815 previously treated patients receiving glyburide or metformin monotherapy who required the addition of the alternative agent, resulting in combination therapy, adherence rates were significantly lower (54.0%; 95% CI, 0.52-0.55) than in the 105 patients receiving monotherapy who were switched to fixed-dose combination therapy (77.0%; 95% CI, 0.72-0.82). The 59 previously treated patients receiving combination therapy who were switched to fixed-dose combination therapy had a significant improvement in adherence after the switch (71.0% vs 87.0%; P < 0.001).

CONCLUSIONS

In a managed care organization, previously treated patients receiving monotherapy with an oral antidiabetic medication who required additional therapy exhibited significantly greater adherence when they were switched to fixed-dose combination therapy compared with combination therapy. Patients receiving combination therapy who were switched to fixed-dose combination therapy exhibited significantly greater adherence after the switch.

The relationship between metformin therapy and the fasting plasma lactate in type 2 diabetes: The Fremantle Diabetes Study

AIMS

To determine (i) which factors, including metformin, are associated with the fasting plasma lactate concentration in type 2 diabetes, and (ii) whether plasma lactate is associated with haemodynamic and metabolic effects.

METHODS

We measured fasting plasma lactate in 272 well-characterized diabetic patients from a community-based sample, 181 (67%) of whom were taking metformin with or without other therapies. Linear regression analysis was used to identify predictors, including metformin therapy, of the plasma lactate, and to investigate associations between plasma lactate and resting pulse rate and serum bicarbonate. Factor analysis assessed independent relationships between groups of cosegregating variables.

RESULTS

Metformin-treated patients had higher plasma lactate concentrations than nonmetformin-treated subjects (geometric mean [s.d. range] 1.86 [1.34-2.59] vs 1.58 [1.09-2.30] mmol x l(-1), respectively; P < 0.001). In a linear regression model, plasma glucose, BMI and metformin use (but not dose) were independently associated with plasma lactate (P < or = 0.028); after adjustment for the former two variables, metformin-treated patients had a mean plasma lactate 0.16 mmol l-1 greater than in subjects not taking the drug. Factor analysis revealed that plasma lactate, plasma glucose, BMI and pulse rate cosegregated but serum bicarbonate was not in this grouping.

CONCLUSIONS

The present results show that metformin therapy increases the fasting plasma lactate in ambulant patients with type 2 diabetes from a community-based cohort. From associations in the data we hypothesize that this increase reflects (i) increased sympathetic activity in patients with the metabolic syndrome (ii) increased substrate (glucose) availability and (iii) a direct metformin effect.

Management of type 2 diabetes mellitus in the elderly: special considerations

The principles of managing type 2 diabetes mellitus in the elderly are no different from those in younger patients, but the priorities and therapeutic strategies need to be cautiously individualised. The objectives of treatment are to improve glycaemic control in a stepwise approach that involves nonpharmacological methods including diet and exercise, and pharmacological therapy including mixtures of oral antihyperglycaemic agents alone or in combination with insulin. Although the goals of treatment may be the same for elderly and younger patients, certain aspects of type 2 diabetes in the elderly require special consideration. Treatment decisions are influenced by age and life expectancy, comorbid conditions and severity of the vascular complications. Adherence to dietary therapy, physical activity, and medication regimens may be compromised by comorbid conditions and psychosocial limitations. Drug-induced hypoglycaemia has been the main consideration and the most serious potential complication. In addition, the long term macrovascular and microvascular complications of type 2 diabetes are a source of significant morbidity and mortality. Indeed, vascular and neuropathic complications are already present at the time of diagnosis in a significant number of patients, and the impact of improved diabetes control depends on the age and life expectancy of the patient. Age-related changes in pharmacokinetics and the potential for adverse effects and drug interactions should also be considered when choosing appropriate pharmacological therapy. In general, a conservative and stepwise approach to the treatment of the elderly patient with type 2 diabetes is suggested; treatment may be initiated with monotherapy, followed by early intervention with a combination of oral agents including a sulphonylurea as a foundation insulin secretagogue in addition to a supplemental insulin sensitiser. Insulin therapy is eventually required if significant hyperglycaemia [glycosylated haemoglobin (HbA1c) >8%] persists despite oral combination therapy. Combination therapy with evening insulin and a long-acting sulphonylurea such as glimepiride is an effective strategy to improve hyperglycaemia in the elderly patient with type 2 diabetes in whom polypharmacy with oral agents is unsuccessful. In addition, such a regimen is simple to follow for the patient who may not be able to adhere to a more complicated insulin regimen. Hyperglycaemia in the elderly can be managed well with practical intervention and a straightforward treatment plan to enhance compliance. Optimal glycaemic control should be possible for every patient if treatment is individualised; however, strict glycaemic control may not be achievable in all patients or even desirable in many elderly patients.

Oral antidiabetic treatment in patients with coronary disease: time-related increased mortality on combined glyburide/metformin therapy over a 7.7-year follow-up

BACKGROUND

A sulfonylurea--usually glyburide--plus metformin constitute the most widely used oral antihyperglycemic combination in clinical practice. Both medications present undesirable cardiovascular effects. The issue whether the adverse effects of each of these pharmacologic agents may be additive and detrimental to the prognosis for coronary patients has not yet been specifically addressed.

HYPOTHESIS

This study was designed to examine the survival in type 2 diabetics with proven coronary artery disease (CAD) receiving a combined glyburide/metformin antihyperglycemic treatment over a long-term follow-up period.

METHODS

The study sample comprised 2,275 diabetic patients, aged 45-74 years, with proven CAD, who were screened but not included in the bezafibrate infarction prevention study. In addition, 9,047 nondiabetic patients with CAD represented a reference group. Diabetics were divided into four groups on the basis of their therapeutic regimen: diet alone (n = 990), glyburide (n = 953), metformin (n = 79), and a combination of the latter two (n = 253).

RESULTS

The diabetic groups presented similar clinical characteristics upon recruitment. Crude mortality rate after a 7.7-year follow-up was lower in nondiabetics (14 vs. 31.6%, p<0.001). Among diabetics, 720 patients died: 260 on diet (mortality 26.3%), 324 on glyburide (34%), 25 on metformin alone (31.6%), and 111 patients (43.9%) on combined treatment (p<0.000001). Time-related mortality was almost equal for patients on metformin and on combined therapy over an intermediate follow-up period of 4 years (survival rates 0.80 and 0.79, respectively). The group on combined treatment presented the worst prognosis over the long-term follow-up, with a time-related survival rate of 0.59 after 7 years, versus 0.68 and 0.70 for glyburide and metformin, respectively. After adjustment to variables for prognosis, the use of the combined treatment was associated with an increased hazard ratio (HR) for all-cause mortality of 1.53 (95% confidence interval [CI] 1.20-1.96), whereas glyburide and metformin alone yielded HR 1.22 (95% CI 1.02-1.45) and HR 1.26 (95% CI 0.81-1.96), respectively.

CONCLUSIONS

We conclude that after a 7.7-year follow-up, monotherapy with either glyburide or metformin in diabetic patients with CAD yielded a similar outcome and was associated with a modest increase in mortality. However, time-related mortality was markedly increased when a combined glyburide/metformin treatment was used.

Non insulin-dependent diabetes mellitus (type 2) secondary failure. Metformin-glibenclamide treatment

The goal of sulphonylurea (S) treatment in Non-Insulin-Dependent Diabetes Mellitus (NIDDM - type 2 diabetes) subjects should be to obtain a satisfactory glycemic control (fasting glycemic levels &#x003C; 140 mg&#x0025;). The loss of an adequate blood glucose control after an initial variable period of S is known as secondary failure (SF). The number of SF are extremely variable among different trials for many reasons, some of which are patient-related: increased food intake, weight gain, non-compliance, poor physical activity, stress, diseases and&#x00F7;or impaired pancreatic beta cell function, desensitization after S chronic therapy, reduced absorption, concomitant therapies. Many therapeutic strategies have been proposed to achieve an adequate metabolic control in type 2 diabetes patients: switch to intensive insulin therapy and subsequent return to S therapy; association with insulin; association with sulphonylureas plus biguanides. The association biguanides and S, in particular glibenclamide plus metformin, is now widely used by diabetologists in SF since glibenclamide improves insulin secretion while metformin exerts its antidiabetic.

Management of type 2 diabetes mellitus and cardiovascular risk: lessons from intervention trials

Although the diagnosis of type 2 (noninsulin-dependent) diabetes mellitus is made when blood glucose levels exceed values which increase the risk of microvascular complications, macrovascular disease is the major complication of type 2 diabetes mellitus. Both epidemiological and prospective data have demonstrated that treatment of hyperglycaemia is markedly effective in reducing the risk of microvascular disease but is less potent in reducing that of myocardial infarction, stroke and peripheral vascular disease. Treatment of other cardiovascular risk factors, although by definition less prevalent than hyperglycaemia, appears to be more effective in preventing macrovascular disease than treatment of hyperglycaemia. In recent years, data from intervention trials have suggested that greater benefits with respect to the prevention of macrovascular disease can be achieved by effective treatment of hypertension and hypercholesterolaemia, and by the use of small doses of aspirin (acetylsalicylic acid) than by treating hyperglycaemia alone. On the other hand, the UK Prospective Diabetes Study (UKPDS), which examined the impact of intensive glucose and blood pressure (BP) control on micro- and macrovascular complications, is the only intervention trial to include only patients with type 2 diabetes mellitus. The UKPDS data, the epidemic increase in the number of patients with type 2 diabetes mellitus and their high cardiovascular risk have, however, initiated several new trials addressing, in particular, the possible benefits of treatment of the most common form of dyslipidaemia (high serum triglyceride and low high density lipoprotein cholesterol levels) in these patients. Type 2 diabetes mellitus is thus a disease associated with a high vascular risk, where the majority of patients need, and are likely to benefit from, pharmacological treatment of several cardiovascular risk factors provided treatment targets have not been achieved by life-style modification.

Energy metabolism and substrates oxidative patterns in type 2 diabetic patients treated with sulphonylurea alone or in combination with metformin

OBJECTIVE

To compare substrates oxidative patterns in type 2 diabetic patients treated with sulphonylurea alone or in combination with metformin.

METHODS

Plasma glucose (PG), plasma insulin (PI) and substrates oxidation rates measured by indirect calorimetry were compared during a test day at 8.00 a.m. (before breakfast), 11.00 a.m. (before the lunch), 2.00 p.m. (2 h after the lunch) and at 5.00 p.m. in 56 diabetic patients treated with diet (group C, n = 14), sulphonylurea (group S, n = 14) or with a sulphonylurea-metformin combination (group SM, n = 28).

RESULTS

The three groups were comparable for age, body mass index (b.m.i.), body composition and PG levels. Mean glucose oxidation (Gox) was increased since mean lipid oxidation (Lox) was decreased in group S in comparison both with group C (3.02+/-0.08 vs. 2.62+/-0.08 g/min/kg/10(3), p < 0.05; 0.53+/-0.04 vs. 0.88+/-0.09 g/min/kg/10(3), p < 0.01). Mean Lox was also decreased in group S in comparison with group SM (0.88+/-0.06 vs. 0.53+/-0.04 g/min1/kg1/10(3), p < 0.0001) whereas the difference in Gox between these latter two groups was only significant in the basal state (1.94+/-0.17 vs. 2.47+/-0.17 g/min1/kg1/10(3), p < 0.05). Mean respiratory quotient (RQ) was increased in group S (0.90+/-0.01) in comparison both with group C (0.86+/-0.01, p < 0.001) and with group SM (0.86+/-0.01, p < 0.001). Mean energy expenditure was lower in group S than in group SM (21.4+/-0.6 vs. 23.6+/-0.6 kcal/min/kg/10(3), p < 0.05). Substrates oxidative patterns, RQ values and energy expenditure were similar in group C and in group SM.

CONCLUSIONS

When compared to patients treated with a sulphonylurea-metformin bitherapy, patients treated with a sulphonylurea monotherapy have a shift in their ratio of fat to carbohydrate oxidation that could make body weight loss more difficult in this latter group.

How long can insulin therapy be avoided in the patient with type 2 diabetes mellitus by use of a combination of metformin and a sulfonylurea?

OBJECTIVE

To assess the effective longevity of combination double oral therapy before insulin or triple oral therapy is needed in patients with type 2 diabetes mellitus.

METHODS

We retrospectively reviewed the outcomes of our first 100 patients with type 2 diabetes who were successfully transferred from twice-daily mixed NPH and regular insulin to a combination of metformin and a sulfonylurea.

RESULTS

Of the 100 study patients, 40 had well-controlled plasma glucose (glycosylated hemoglobin levels <8.0%) with use of metformin and a sulfonylurea. Good glycemic control was achieved with triple oral therapy (a sulfonylurea, metformin, and a thiazolidinedione) in 14 patients and with a sulfonylurea, metformin, and evening-administered mixed NPH and regular insulin in 7. In addition, plasma glucose was effectively controlled with twice-daily mixed NPH and regular insulin in conjunction with metformin or a thiazolidinedione (or both) in 22 patients and with twice-daily mixed NPH and regular insulin alone in 17. The mean time (+/- standard error) from primary failure of sulfonylurea monotherapy to the time when a third hypoglycemic agent was needed was 7.9 +/- 1.1 years (95% confidence interval, 5.7 to 10.1).

CONCLUSION

When oral monotherapy fails (that is, glycosylated hemoglobin values exceed 8.0%) in patients with type 2 diabetes, combination therapy with a sulfonylurea and metformin is potentially effective in maintaining glycemic control and avoiding the addition of insulin or a thiazolidinedione for a mean duration of 7.9 years.

Combining sulfonylureas and other oral agents

Type 2 diabetes mellitus is a progressive disorder, and although oral monotherapy is often initially successful, it is associated with a high secondary failure rate, which contributes to the development of long-term diabetes complications resulting from persistent hyperglycemia. For patients not taking insulin, accumulating evidence suggests that combination therapy using oral antidiabetic agents with different mechanisms of action may be highly effective in achieving and maintaining target blood glucose levels. Low-dose combination therapy may be associated with fewer side effects than higher-dose monotherapy and may achieve similar or better glycemic control. The best-studied combination is that of sulfonylurea compounds plus metformin, a therapeutic approach that addresses both underlying defects in the disorder: insulin deficiency and insulin resistance. Other multidrug regimens under investigation are sulfonylurea compounds plus either alpha-glucosidase inhibitors or thiazolidinediones, and combinations of various insulin-sensitizing agents. For many patients, combination oral therapy may be used appropriately as primary management early in the course of type 2 diabetes, along with diet modification and exercise. Later in the course of the disease, the use of combinations of oral agents may delay the need for insulin while maintaining glycemic control, thus making aggressive oral treatment more acceptable for many patients.

Dimethylbiguanide inhibits cell respiration via an indirect effect targeted on the respiratory chain complex I

We report here a new mitochondrial regulation occurring only in intact cells. We have investigated the effects of dimethylbiguanide on isolated rat hepatocytes, permeabilized hepatocytes, and isolated liver mitochondria. Addition of dimethylbiguanide decreased oxygen consumption and mitochondrial membrane potential only in intact cells but not in permeabilized hepatocytes or isolated mitochondria. Permeabilized hepatocytes after dimethylbiguanide exposure and mitochondria isolated from dimethylbiguanide pretreated livers or animals were characterized by a significant inhibition of oxygen consumption with complex I substrates (glutamate and malate) but not with complex II (succinate) or complex IV (N,N,N',N'-tetramethyl-1, 4-phenylenediamine dihydrochloride (TMPD)/ascorbate) substrates. Studies using functionally isolated complex I obtained from mitochondria isolated from dimethylbiguanide-pretreated livers or rats further confirmed that dimethylbiguanide action was located on the respiratory chain complex I. The dimethylbiguanide effect was temperature-dependent, oxygen consumption decreasing by 50, 20, and 0% at 37, 25, and 15 degrees C, respectively. This effect was not affected by insulin-signaling pathway inhibitors, nitric oxide precursor or inhibitors, oxygen radical scavengers, ceramide synthesis inhibitors, or chelation of intra- or extracellular Ca(2+). Because it is established that dimethylbiguanide is not metabolized, these results suggest the existence of a new cell-signaling pathway targeted to the respiratory chain complex I with a persistent effect after cessation of the signaling process.

Poorly controlled elderly Type 2 diabetic patients: the effects of increasing sulphonylurea dosages or adding metformin

AIMS

To assess the effects and safety of increasing sulphonylurea dosages or adding metformin in poorly controlled elderly Type 2 diabetic patients.

METHODS

A 18-month multicentre clinical study was performed on sulphonylurea-treated diabetic patients over 70 years of age with well-preserved renal function, steady fasting blood glucose > or = 200 mg/dl and HbA1c > or = 9%. Patients were randomly assigned to sulphonylurea increased up to its maximum dosage (1st group) or to addition of metformin (2nd group). Glycaemic control, lipid pattern, haemostatic status and safety were monitored during run-in, at baseline and at scheduled intervals for 18 months. Results refer to 85 patients in the 1st group and 89 patients in the 2nd with complete data.

RESULTS

Similar improvements in glycaemic levels were observed with both treatments within the first month and a similar decrease in HbA1c within the third month. No further changes occurred in glycaemic control. In the 1st group, fasting glucose (mmol/l, mean +/- SE) decreased from 14.21 +/- 0.49 to 9.88 +/- 0.21, average day-long glucose from 14.87 +/- 0.27 to 10.69 +/- 0.19 and HbAt1c(%) from 10.32 +/- 0.13 to 8.66 +/- 0.13. In the 2nd treatment group fasting glucose decreased from 14.59 +/- 0.61 to 9.05 +/- 37.28, average day-long glucose from 15.09 +/- 0.29 to 10.32 +/- 0.21 and HbA1c from 10.33 +/- 0.13 to 8.77+/-0.12 (for all P<0.0005). In this 2nd group, a decrease in LDL-cholesterol (P < 0.05) and an increase in HDL-cholesterol levels (P < 0.02) were also observed. In the 1st group, anthrombin III activity increased significantly (P<0.01). In the 2nd group, significant reductions in markers of platelet function (FP4 and betaTG, P < 0.01), thrombin generation (FPA, F1 + 2 and D-D, P<0.01), and fibrinolysis inhibition (PAI-1 activity, PAI-1 antigen, P< 0.001) were observed. Increases in some fibrinolytic activation markers (t-PA activity, and AT-III activity, P<0.01) occurred. Fasting lactate concentrations were unchanged in the metformin-treated group. No serious adverse effects were observed in either group.

CONCLUSIONS

These results suggest that either high sulphonylurea dosages or a therapy combining lower sulphonylurea dosages with metformin are effective and safe in an aged but healthy population. Metformin provides additional benefits counteracting several cardiovascular risk factors but must be administered with caution, bearing in mind the general contra-indications for the drug but not age alone.

Pharmacologic therapy for type 2 diabetes mellitus

Type 2 diabetes mellitus is a chronic metabolic disorder that results from defects in both insulin secretion and insulin action. An elevated rate of basal hepatic glucose production in the presence of hyperinsulinemia is the primary cause of fasting hyperglycemia; after a meal, impaired suppression of hepatic glucose production by insulin and decreased insulin-mediated glucose uptake by muscle contribute almost equally to postprandial hyperglycemia. In the United States, five classes of oral agents, each of which works through a different mechanism of action, are currently available to improve glycemic control in patients with type 2 diabetes. The recently completed United Kingdom Prospective Diabetes Study (UKPDS) has shown that type 2 diabetes mellitus is a progressive disorder that can be treated initially with oral agent monotherapy but will eventually require the addition of other oral agents, and that in many patients, insulin therapy will be needed to achieve targeted glycemic levels. In the UKPDS, improved glycemic control, irrespective of the agent used (sulfonylureas, metformin, or insulin), decreased the incidence of microvascular complications (retinopathy, neuropathy, and nephropathy). This review examines the goals of antihyperglycemic therapy and reviews the mechanism of action, efficacy, nonglycemic benefits, cost, and safety profile of each of the five approved classes of oral agents. A rationale for the use of these oral agents as monotherapy, in combination with each other, and in combination with insulin is provided.

A risk-benefit assessment of metformin in type 2 diabetes mellitus

Metformin has been used for over 40 years as an effective glucose-lowering agent in type 2 (noninsulin-dependent) diabetes mellitus. Typically it reduces basal and postprandial hyperglycaemia by about 25% in more than 90% of patients when either given alone or coadministered with other therapies including insulin during a programme of managed care. Metformin counters insulin resistance and offers benefits against many features of the insulin resistance syndrome (Syndrome X) by preventing bodyweight gain, reducing hyperinsulinaemia and improving the lipid profile. In contrast to sulphonylureas, metformin does not increase insulin secretion or cause serious hypoglycaemia. Treatment of type 2 diabetes mellitus with metformin from diagnosis also offers greater protection against the chronic vascular complications of type 2 diabetes mellitus. The most serious complication associated with metformin is lactic acidosis which has an incidence of about 0.03 cases per 1000 patients years of treatment and a mortality risk of about 0.015 per 1000 patient-years. Most cases occur in patients who are wrongly prescribed the drug, particularly patients with impaired renal function (e.g. serum creatinine level > 130 micromol/L or > 1.5 g/L). Other major contraindications include congestive heart failure, hypoxic states and advanced liver disease. Serious adverse events with metformin are predictable rather than spontaneous and are potentially preventable if the prescribing guidelines are respected. Gastrointestinal adverse effects, notably diarrhoea, occur in less than 20% of patients and remit when the dosage is reduced. The life-threatening risks associated with metformin are rare and could mostly be avoided by strict adherence to the prescribing guidelines. Given the 4 decades of clinical experience with metformin, its antihyperglycaemic efficacy and benefits against Syndrome X, metformin offers a very favourable risk-benefit assessment when compared with the chronic morbidity and premature mortality among patients with type 2 diabetes mellitus.

Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes (UKPDS 34). UK Prospective Diabetes Study (UKPDS) Group

BACKGROUND

In patients with type 2 diabetes, intensive blood-glucose control with insulin or sulphonylurea therapy decreases progression of microvascular disease and may also reduce the risk of heart attacks. This study investigated whether intensive glucose control with metformin has any specific advantage or disadvantage.

METHODS

Of 4075 patients recruited to UKPDS in 15 centres, 1704 overweight (>120% ideal bodyweight) patients with newly diagnosed type 2 diabetes, mean age 53 years, had raised fasting plasma glucose (FPG; 6.1-15.0 mmol/L) without hyperglycaemic symptoms after 3 months' initial diet. 753 were included in a randomised controlled trial, median duration 10.7 years, of conventional policy, primarily with diet alone (n=411) versus intensive blood-glucose control policy with metformin, aiming for FPG below 6 mmol/L (n=342). A secondary analysis compared the 342 patients allocated metformin with 951 overweight patients allocated intensive blood-glucose control with chlorpropamide (n=265), glibenclamide (n=277), or insulin (n=409). The primary outcome measures were aggregates of any diabetes-related clinical endpoint, diabetes-related death, and all-cause mortality. In a supplementary randomised controlled trial, 537 non-overweight and overweight patients, mean age 59 years, who were already on maximum sulphonylurea therapy but had raised FPG (6.1-15.0 mmol/L) were allocated continuing sulphonylurea therapy alone (n=269) or addition of metformin (n=268).

FINDINGS

Median glycated haemoglobin (HbA1c) was 7.4% in the metformin group compared with 8.0% in the conventional group. Patients allocated metformin, compared with the conventional group, had risk reductions of 32% (95% CI 13-47, p=0.002) for any diabetes-related endpoint, 42% for diabetes-related death (9-63, p=0.017), and 36% for all-cause mortality (9-55, p=0.011). Among patients allocated intensive blood-glucose control, metformin showed a greater effect than chlorpropamide, glibenclamide, or insulin for any diabetes-related endpoint (p=0.0034), all-cause mortality (p=0.021), and stroke (p=0.032). Early addition of metformin in sulphonylurea-treated patients was associated with an increased risk of diabetes-related death (96% increased risk [95% CI 2-275], p=0.039) compared with continued sulphonylurea alone. A combined analysis of the main and supplementary studies showed fewer metformin-allocated patients having diabetes-related endpoints (risk reduction 19% [2-33], p=0.033). Epidemiological assessment of the possible association of death from diabetes-related causes with the concurrent therapy of diabetes in 4416 patients did not show an increased risk in diabetes-related death in patients treated with a combination of sulphonylurea and metformin (risk reduction 5% [-33 to 32], p=0.78).

INTERPRETATION

Since intensive glucose control with metformin appears to decrease the risk of diabetes-related endpoints in overweight diabetic patients, and is associated with less weight gain and fewer hypoglycaemic attacks than are insulin and sulphonylureas, it may be the first-line pharmacological therapy of choice in these patients.

Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). UK Prospective Diabetes Study (UKPDS) Group

BACKGROUND

Improved blood-glucose control decreases the progression of diabetic microvascular disease, but the effect on macrovascular complications is unknown. There is concern that sulphonylureas may increase cardiovascular mortality in patients with type 2 diabetes and that high insulin concentrations may enhance atheroma formation. We compared the effects of intensive blood-glucose control with either sulphonylurea or insulin and conventional treatment on the risk of microvascular and macrovascular complications in patients with type 2 diabetes in a randomised controlled trial.

METHODS

3867 newly diagnosed patients with type 2 diabetes, median age 54 years (IQR 48-60 years), who after 3 months' diet treatment had a mean of two fasting plasma glucose (FPG) concentrations of 6.1-15.0 mmol/L were randomly assigned intensive policy with a sulphonylurea (chlorpropamide, glibenclamide, or glipizide) or with insulin, or conventional policy with diet. The aim in the intensive group was FPG less than 6 mmol/L. In the conventional group, the aim was the best achievable FPG with diet alone; drugs were added only if there were hyperglycaemic symptoms or FPG greater than 15 mmol/L. Three aggregate endpoints were used to assess differences between conventional and intensive treatment: any diabetes-related endpoint (sudden death, death from hyperglycaemia or hypoglycaemia, fatal or non-fatal myocardial infarction, angina, heart failure, stroke, renal failure, amputation [of at least one digit], vitreous haemorrhage, retinopathy requiring photocoagulation, blindness in one eye, or cataract extraction); diabetes-related death (death from myocardial infarction, stroke, peripheral vascular disease, renal disease, hyperglycaemia or hypoglycaemia, and sudden death); all-cause mortality. Single clinical endpoints and surrogate subclinical endpoints were also assessed. All analyses were by intention to treat and frequency of hypoglycaemia was also analysed by actual therapy.

FINDINGS

Over 10 years, haemoglobin A1c (HbA1c) was 7.0% (6.2-8.2) in the intensive group compared with 7.9% (6.9-8.8) in the conventional group--an 11% reduction. There was no difference in HbA1c among agents in the intensive group. Compared with the conventional group, the risk in the intensive group was 12% lower (95% CI 1-21, p=0.029) for any diabetes-related endpoint; 10% lower (-11 to 27, p=0.34) for any diabetes-related death; and 6% lower (-10 to 20, p=0.44) for all-cause mortality. Most of the risk reduction in the any diabetes-related aggregate endpoint was due to a 25% risk reduction (7-40, p=0.0099) in microvascular endpoints, including the need for retinal photocoagulation. There was no difference for any of the three aggregate endpoints between the three intensive agents (chlorpropamide, glibenclamide, or insulin). Patients in the intensive group had more hypoglycaemic episodes than those in the conventional group on both types of analysis (both p<0.0001). The rates of major hypoglycaemic episodes per year were 0.7% with conventional treatment, 1.0% with chlorpropamide, 1.4% with glibenclamide, and 1.8% with insulin. Weight gain was significantly higher in the intensive group (mean 2.9 kg) than in the conventional group (p<0.001), and patients assigned insulin had a greater gain in weight (4.0 kg) than those assigned chlorpropamide (2.6 kg) or glibenclamide (1.7 kg).

INTERPRETATION

Intensive blood-glucose control by either sulphonylureas or insulin substantially decreases the risk of microvascular complications, but not macrovascular disease, in patients with type 2 diabetes.(ABSTRACT TRUNCATED)