Effect of metformin and rosiglitazone combination therapy in patients with type 2 diabetes mellitus: a randomized controlled trial

Effects of a medication assistance program on health outcomes in patients with type 2 diabetes mellitus

PURPOSE

The effects of a clinic-based medication assistance program (MAP) on the health outcomes and medication use of patients with type 2 diabetes mellitus were studied.

METHODS

In this retrospective analysis, data from the University of Arkansas for Medical Sciences pharmacy-managed MAP and outpatient pharmacy databases were collected for adult patients with type 2 diabetes mellitus who were monitored in the university's internal medicine clinic one year before and after enrollment in the MAP. Data on patient demographics, medication use, and disease indicators (glycosylated hemoglobin [HbA(1c)], high-density-lipoprotein [HDL] cholesterol, low-density-lipoprotein [LDL] cholesterol, total cholesterol, triglyceride, and blood pressure levels) were collected for the year before enrollment and for one year after enrollment. Statistical analyses were conducted using descriptive analyses, paired t tests, and the Wilcoxon signed rank test.

RESULTS

Of the 401 patients enrolled in the internal medicine clinic who were enrolled in the MAP, sufficient data were available for 52 patients, of whom 73% were women, 50% were African American, and 48% were white. Their mean age was 59 years. All were self-paying customers, with 67.3% receiving Medicare benefits. Patients received more prescription medications (p < 0.001) and antihyperglycemic medications (p = 0.001) after enrollment in the program. Mean HbA(1c) and LDL cholesterol levels decreased significantly after enrollment (p < 0.001 for both). Mean HDL cholesterol levels and systolic and diastolic blood pressure measurements did not change significantly.

CONCLUSION

A clinic-based MAP managing the use of pharmaceutical manufacturers' drug assistance programs increased indigent patients' access to antihyperglycemic medications and improved patients' clinical outcomes.

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.

The effect of metformin and rosiglitazone on postprandial lipid metabolism in obese insulin-resistant subjects

INTRODUCTION

Obese insulin-resistant individuals exhibit a dyslipidaemia due to raised levels of both hepatically and intestinally derived lipoproteins. However, little is known about the related dysregulation of intestinally derived lipoproteins. We examined whether the insulin-sensitizing agents, metformin and rosiglitazone, improve intestinal lipoprotein metabolism in obese insulin-resistant individuals.

METHODS

Thirty male obese (body mass index > 26; waist circumference > 100 cm) insulin-resistant [homeostasis model assessment (HOMA) score > 2.0] subjects were randomized to either a metformin (1 g bd), rosiglitazone (4 mg bd) or control treatment group for a period of 8 weeks. Fasting and postprandial lipid metabolism was studied before and after the intervention period.

RESULTS

Metformin and rosiglitazone both significantly improved insulin sensitivity, but this was not paralleled by improvement in dyslipidaemia. With rosiglitazone relative to control there was a significant (p < 0.05) increase in the area under the apolipoprotein (apo) B48 curve following the oral fat load and a decrease in the ratio of triglyceride to apo B48 levels postprandially following rosiglitazone treatment.

CONCLUSION

In obese insulin-resistant subjects metformin and rosiglitazone both improve insulin sensitivity, as measured by HOMA, without improvement in lipid metabolism. Rosiglitazone may have a detrimental effect on chylomicron metabolism by an increase in postprandial apo B48 levels, and this requires further investigation.

Insulin-sensitizing antihyperglycemic drugs and mortality after acute myocardial infarction: insights from the National Heart Care Project

OBJECTIVE

Thiazolidinediones (TZDs) and metformin are insulin-sensitizing antihyperglycemic agents with reported benefits on atherosclerosis. Despite extensive use in patients with diabetes and cardiovascular disease, there is a paucity of outcomes data with metformin and none yet with TZDs. We sought to determine the impact of these insulin sensitizers on outcomes in diabetic patients after hospitalization with acute myocardial infarction (AMI).

RESEARCH DESIGN AND METHODS

We conducted a retrospective cohort study of 24,953 Medicare beneficiaries with diabetes discharged after hospitalization with AMI between April 1998 and March 1999 or July 2000 and June 2001. The independent association between discharge prescription for metformin, TZD, or both agents and outcomes at 1 year was assessed in multivariable Cox proportional hazards models, adjusting for patient, physician, and hospital variables. The primary outcome was time to death within 1 year of discharge; secondary outcomes were time to first rehospitalization within 1 year of discharge for AMI, heart failure, and all causes.

RESULTS

There were 8,872 patients discharged on an antihyperglycemic agent, of which 819 were prescribed a TZD, 1,273 metformin, and 139 both drugs. After multivariable analysis, compared with patients prescribed an antihyperglycemic regimen that included no insulin sensitizer, mortality rates were not significantly different in patients treated with either metformin (hazard ratio [HR] 0.92 [95% CI 0.81-1.06]) or a TZD (0.92 [0.80-1.05]) but were lower in those prescribed both drugs (0.52 [0.34-0.82]). The results were similar among patients with heart failure. The prescription of a TZD was associated with a borderline higher risk of all-cause readmission (1.09[1.00-1.20]), predominately due to a higher risk for heart failure readmission (1.17 [1.05-1.30]).

CONCLUSIONS

Individually, prescription of insulin-sensitizing drugs is not associated with a significantly different risk of death in older diabetic patients within 1 year following AMI compared with other antihyperglycemic agents. Combined, however, metformin and TZDs may exert benefit. TZD prescription is associated with a higher risk of readmission for heart failure after myocardial infarction.

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.

Addressing the Global Cardiovascular Risk of Hypertension, Dyslipidemia, Diabetes Mellitus, and the Metabolic Syndrome in the Southeastern United States, Part II: Treatment Recommendations for Management of the Global Cardiovascular Risk of Hypertension, Dyslipidemia, Diabetes Mellitus, and the Metabolic Syndrome

An aggressive global approach to screening and to the management of the metabolic syndrome is recommended to slow the growth of the syndrome throughout the United States. Prevention should begin in childhood with healthy nutrition, daily physical activity, and annual measurement of weight, height, and blood pressure beginning at 3 years of age. Such screenings will identify cardiovascular risk factors early, allow the health care provider to define global cardiovascular risk with the COSEHC Cardiovascular Risk Assessment Tool, and allow treatment of each risk factor. Lifelong lifestyle modifications and pharmacologic therapy will be required in most patients. Antihypertensive therapy for these patients should begin with an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker unless a compelling indication for another drug is present. Metformin should be considered the first drug for glucose control in the patient with type 2 diabetes. A statin should be used initially for hyperlipidemia unless contraindicated. Combinations of antihypertensive, antiglycemic, and lipid-lowering agents will often be required.

Spotlight on rosiglitazone in the management of type 2 diabetes mellitus

Rosiglitazone, a thiazolidinedione with a different side chain from those of troglitazone and pioglitazone, reduces plasma glucose levels and glucose production and increases glucose clearance in patients with type 2 diabetes mellitus. Insulin sensitivity, pancreatic beta-cell function and surrogate markers of cardiovascular risk factors are significantly improved by rosiglitazone. Double-blind trials of 8 to 26 weeks of rosiglitazone 4 or 8 mg/day monotherapy indicate significant decreases in fasting plasma glucose (-2 to -3 mmol/L with 8 mg/day) and glycosylated hemoglobin levels [HbA(1c); -0.6 to -0.7% (-0.8 to -1.1% in drug-naive patients) with 8 mg/day]. Significant decreases in hyperglycemic markers occurred when rosiglitazone was combined with metformin (HbA(1c) -0.8 to -1.0%), a sulfonylurea (-1.4%) or insulin (-1.2%) for 26 weeks versus little change with active comparator monotherapy. Efficacy was maintained in trials of < or =2 years, and was also apparent in various ethnic subgroups, elderly patients and both obese and nonobese patients. Rosiglitazone is currently not indicated in combination with injected insulin. It should be administered in conjunction with diet and exercise regimens. Rosiglitazone is generally well tolerated. Despite rare individual reports of liver function abnormalities in rosiglitazone recipients, the incidence of these in clinical trials (< or =2 years' duration) was similar to that in placebo and active comparator groups. Fluid retention associated with rosiglitazone may be the cause of the increased incidence of anemia in clinical trials, and also means that patients should be monitored for signs of heart failure during therapy. Although bodyweight is increased overall with rosiglitazone therapy, increases are in subcutaneous, not visceral, fat; hepatic fat is decreased. The pharmacokinetic profile of rosiglitazone is not substantially altered by age or renal impairment, nor are there important drug interactions. Rosiglitazone is not indicated in patients with active liver disease or increased liver enzymes.

CONCLUSIONS

Oral rosiglitazone 4 or 8 mg/day provides significant antihyperglycemic efficacy and is generally well tolerated, both as monotherapy and in combination with other antihyperglycemic agents, in patients with type 2 diabetes mellitus who do not have active liver disease. Long-term data are required before conclusions can be drawn about the clinical significance of positive changes to surrogate markers of cardiovascular disease risk and improvements to pancreatic beta-cell function. Rosiglitazone significantly improves insulin sensitivity and, as such, is a welcome addition to the treatment options for patients with type 2 diabetes mellitus.

Thiazolidinediones-benefits on microvascular complications of type 2 diabetes

Type 2 diabetes is associated with serious microvascular complications, such as nephropathy, retinopathy, and neuropathy, which have a significant impact on patients' quality of life, morbidity, and mortality. Type 2 diabetes management strategies to reduce the risk of microvascular complications include treatment of hyperglycaemia, hypertension, and other vascular risk factors. The importance of glycaemic control in reducing the risk of microvascular complications of diabetes is well established. However, many antihyperglycaemic therapies fail to provide adequate glycaemic control and do not prevent complications in the long term. The thiazolidinediones (TZDs) are a class of agents that provide sustained glycaemic control, mediated primarily by reductions in insulin resistance. Evidence reviewed suggests that the TZDs may have the potential to reduce microvascular complications through benefits that go beyond glycaemic control. Insulin resistance underlies a range of metabolic abnormalities, collectively known as the metabolic syndrome (MS), which are cardiovascular (CV) risk factors. Components include visceral obesity, hyperglycaemia, hypertension, dyslipidaemia, low-grade inflammation and microalbuminuria (an early manifestation of target organ damage). Reducing insulin resistance, therefore, has the potential to reduce both microvascular and macrovascular complications.

Effects of metformin and rosiglitazone treatment on insulin signaling and glucose uptake in patients with newly diagnosed type 2 diabetes: a randomized controlled study

The effect of metformin or rosiglitazone monotherapy versus placebo on insulin signaling and gene expression in skeletal muscle of patients with newly diagnosed type 2 diabetes was determined. A euglycemic-hyperinsulinemic clamp, combined with skeletal muscle biopsies and glucose uptake measurements over rested and exercised muscle, was performed before and after 26 weeks of metformin (n = 9), rosiglitazone (n = 10), or placebo (n = 11) treatment. Insulin-mediated whole-body and leg muscle glucose uptake was enhanced 36 and 32%, respectively, after rosiglitazone (P < 0.01) but not after metformin or placebo treatment. Insulin increased insulin receptor substrate 1 (IRS-1) tyrosine phosphorylation, IRS-1-associated phosphatidylinositol (PI) 3-kinase activity, and phosphorylation of Akt Ser473 and AS160, a newly described Akt substrate that plays a role in GLUT4 exocytosis, approximately 2.3 fold before treatment. These insulin signaling parameters were unaltered after metformin, rosiglitazone, or placebo treatment. Expression of selected genes involved in glucose and fatty acid metabolism in skeletal muscle was unchanged between the treatment groups. Low-intensity acute exercise increased insulin-mediated glucose uptake but was without effect on insulin signaling. In conclusion, the insulin-sensitizing effects of rosiglitazone are independent of enhanced signaling of IRS-1/PI 3-kinase/Akt/AS160 in patients with newly diagnosed type 2 diabetes.

Effects of exenatide (exendin-4) on glycemic control and weight over 30 weeks in metformin-treated patients with type 2 diabetes

OBJECTIVE

This study evaluates the ability of the incretin mimetic exenatide (exendin-4) to improve glycemic control in patients with type 2 diabetes failing to achieve glycemic control with maximally effective metformin doses.

RESEARCH DESIGN AND METHODS

A triple-blind, placebo-controlled, 30-week study at 82 U.S. sites was performed with 336 randomized patients. In all, 272 patients completed the study. The intent-to-treat population baseline was 53 +/- 10 years with BMI of 34.2 +/- 5.9 kg/m(2) and HbA(1c) of 8.2 +/- 1.1%. After 4 weeks of placebo, subjects self-administered 5 microg exenatide or placebo subcutaneously twice daily for 4 weeks followed by 5 or 10 microg exenatide, or placebo subcutaneously twice daily for 26 weeks. All subjects continued metformin therapy.

RESULTS

At week 30, HbA(1c) changes from baseline +/- SE for each group were -0.78 +/- 0.10% (10 microg), -0.40 +/- 0.11% (5 microg), and +0.08 +/- 0.10% (placebo; intent to treat; adjusted P < 0.002). Of evaluable subjects, 46% (10 microg), 32% (5 microg), and 13% (placebo) achieved HbA(1c) < or =7% (P < 0.01 vs. placebo). Exenatide-treated subjects displayed progressive dose-dependent weight loss (-2.8 +/- 0.5 kg [10 microg], -1.6 +/- 0.4 kg [5 microg]; P < 0.001 vs. placebo). The most frequent adverse events were gastrointestinal in nature and generally mild to moderate. Incidence of mild to moderate hypoglycemia was low and similar across treatment arms, with no severe hypoglycemia.

CONCLUSIONS

Exenatide was generally well tolerated and reduced HbA(1c) with no weight gain and no increased incidence of hypoglycemia in patients with type 2 diabetes failing to achieve glycemic control with metformin.

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

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

Effect on glycemic control of the addition of 2.5 mg glipizide GITS to metformin in patients with T2DM

AIMS

This study evaluated the effects on glycemic control of the addition of 2.5 mg glipizide GITS to metformin in patients with mild-to-moderate, but suboptimally controlled type 2 diabetes.

METHODS

In this multicenter, double-blind, placebo-controlled study, 122 patients with type 2 diabetes inadequately controlled (A1c 7-8.5%) on metformin (> or =1000 mg/day for > or =3 months) were randomized to 16 weeks treatment with 2.5 mg/day glipizide GITS (n=61) or placebo (n=61), in addition to their current metformin dose. The primary efficacy variable was the change in A1c from baseline to endpoint. Changes in fasting plasma glucose (FPG), insulin concentrations, lipid profile and safety variables were also measured.

RESULTS

The addition of glipizide GITS to metformin gave significantly greater improvements in mean A1c and FPG from baseline to endpoint than placebo addition (p<0.0002). Significantly more patients in the glipizide GITS group than in the placebo group achieved the target A1c level of A1c<7.0% (p<0.0001) and an A1c<6.5% (p<0.0033). Fasting insulin concentrations were similar in both groups and unchanged by treatment. Addition of glipizide GITS to metformin did not produce any significant or clinically relevant weight gain or changes in BMI. Both treatment regimens were well tolerated.

CONCLUSIONS

This study showed that the addition of 2.5 mg glipizide GITS to metformin significantly improved glucose control in patients with type 2 diabetes inadequately controlled by metformin monotherapy.

The role of thiazolidinediones in the treatment of patients with type 2 diabetes mellitus

Diabetes mellitus is a significant and growing health concern worldwide. Unfortunately, type 2 diabetes mellitus is generally under-managed, and this may explain the increasing prevalence of diabetic complications throughout the world. The introduction of newer classes of antihyperglycemic agents should enhance the ability of clinicians to achieve optimal blood glucose control. One recent addition to the pharmacologic armamentarium is the thiazolidinedione class. The main effect of thiazolidinediones is amelioration of insulin resistance. These agents may also preserve beta-cell function, although evidence in favor of this effect is still inconclusive. The mechanism of action of thiazolidinediones is not completely understood. Similarly, the current state of knowledge cannot explain the differences in the lipid effects of pioglitazone and rosiglitazone. Thiazolidinediones are commonly used as add-on therapy for those requiring large daily doses of insulin therapy, or in addition to sulfonylurea agents and metformin for those reluctant to start insulin therapy. The potential role of thiazolidinediones as first-line therapy is now emerging. It is possible that in certain subgroups, particularly patients with renal failure, elderly individuals or those with corticosteroid-induced diabetes mellitus, the use of thiazolidinediones as a first-line therapy is justifiable. However, the lack of a long-term safety record, and the cost, would limit the widespread acceptance of this class of agents as first-line therapy.

Multidimensional Pharmacologic Strategies for Diabetes

Diabetes is a chronic disease associated with multisystem complications. In particular, cardiovascular and renal demise are almost certain in individuals who have diabetes, with cardiovascular complications account-ing for over 50% of mortality among patients who have type 2 diabetes mellitus. Documented benefits of lowering cholesterol, blood pressure, and glucose levels in these patients have led to the current emphasis on multidimensional pharmacologic management. Table 2 provides a summary of recommendations for managing patients who have type 2 diabetes.

Potential cardiovascular benefits of insulin sensitizers

A multiple risk factor approach is needed in patients who have type 2 diabetes. Because many risk factors are linked with IR, treatment with insulin sensitizers has the potential to modulate these risk factors favorably. TZDs 'have many important effects beyond lowering blood glucose. By targeting IR, they improve many cardiovascular risk factors that are associated with the IR syndrome. In particular, they increase HDL-C, have anti-inflammatory effects, improve endothelial function and fibrinolysis, and decrease carotid intimal thickness; however, no evidence-based studies on cardiovascular outcomes are available to substantiate the potential cardioprotective effects of TZDs. Several clinical trials that were designed to investigate the effect that these agents have on reducing cardiovascular events are well under way.

Glycemic management of type 2 diabetes: an emerging strategy with oral agents, insulins, and combinations

The many antihyperglycemic preparations are best used for type 2 diabetes in a logical sequence, using combinations of agents, with clear targets for glycemic control. On the basis of long familiarity, proven benefit and known side effects, and low cost, the sulfonylureas, metformin, and insulin still deserve to be the standard treatments. As shown in the central shaded area of Fig. 4, standard treatment begins with monotherapy and progresses to oral combination therapy and then to two oral agents plus basal insulin. Several triggers for deviation from the standard methods are identified (see Fig. 4). The incidence of each of the conditions that require early individualized treatment has not been studied, but it seems reasonable to estimate no more than 10% each for a strongly symptomatic presentation, inability to use a sulfonylurea or metformin, inability to use insulin, or an early need for prandial therapy. If this estimate is correct, approximately two thirds of patients who are diagnosed with type 2 diabetes should do well with standard therapy for up to 10 years using the standard methods shown. Eventually, many more will need individualized treatment to maintain glycemic control. This scheme is certain to evolve as further information on the nonglycemic benefits (or hazards) of the various therapies appears and as new treatments are released. Notably, agents that mimic or potentiate the effects of gastrointestinal peptides, such as amylin and GLP- 1 analogues and dipeptidyl peptidase IV inhibitors, are likely to alter the current algorithm. For now, systematic application of the scheme (see Fig. 4) should improve the success of treatment greatly from its currently disappointing level.

Ambulatory blood pressure reduction after rosiglitazone treatment in patients with type 2 diabetes and hypertension correlates with insulin sensitivity increase

BACKGROUND

Within the metabolic syndrome, insulin resistance and compensatory hyperinsulinemia are associated with blood pressure (BP) elevation through various potential mechanisms. Thiazolidinediones are antihyperglycemic agents that decrease insulin resistance.

OBJECTIVE

To determine the effect of the thiazolidinedione rosiglitazone on BP and insulin resistance in patients with type 2 diabetes and hypertension.

METHODS

In 20 subjects (nine men and 11 women) with type 2 diabetes but with a poor glycemic control, and with poorly controlled or newly diagnosed hypertension, rosiglitazone 4 mg daily was added-on therapy for 26 weeks. At baseline and at the end of the treatment period patients underwent ambulatory blood pressure monitoring, a hyperinsulinemic euglycemic clamp, and blood tests for glucose, insulin, HbA1c, lipids, and routine laboratory parameters.

RESULTS

Insulin sensitivity estimated with the clamp significantly increased (Mbw/I index changed from 33.9 +/- 2.6 to 41.9 +/- 3.2 micromol/min per kg per nmol/l, P < 0.001) and the HOMA-IR index significantly decreased (6.34 +/- 0.39 versus 4.40 +/- 0.33, P < 0.001) during rosiglitazone treatment. Ambulatory BP presented small but significant reductions for the total 24-h period (135.3 +/- 1.8 versus 129.9 +/- 1.7 mmHg, P < 0.001 for systolic BP and 76.0 +/- 1.6 versus 71.9 +/- 1.6 mmHg, P < 0.001 for diastolic BP), daytime and night-time. The changes in systolic and diastolic BP correlated with the change in insulin sensitivity (r = -0.78, P < 0.01 and r = -0.68, P < 0.01, respectively). There were also significant reductions in fasting plasma glucose (9.39 +/- 0.41 versus 7.55 +/- 0.31 mmol/l, P < 0.001), insulin (94.0 +/- 0.41 versus 79.5 +/- 5.6 pmol/l, P < 0.01) and HbA1c (8.15 +/- 0.24 versus 7.24 +/- 0.19%, P < 0.001).

CONCLUSIONS

Treatment of type 2 diabetic hypertensive patients with rosiglitazone significantly increased insulin sensitivity and lowered ambulatory BP. These changes were strongly correlated. Thiazolidinediones may thus possess a BP-lowering effect beyond their antihyperglycemic properties.

Case-based study: from prediabetes to complications--opportunities for prevention

A 31-year-old man presents with central obesity, hypertension, and abnormal lipids. How would you manage this patient?

Multiplicity adjustment for multiple endpoints in clinical trials with multiple doses of an active treatment

Frequently, multiple doses of an active treatment and multiple endpoints are simultaneously considered in the designs of clinical trials. For these trials, traditional multiplicity adjustment procedures such as Bonferroni, Hochberg and Hommel procedures can be applied when treating the comparisons of different doses to the control on all endpoints at the same level. However, these approaches will not take into account the possible dose-response relationship on each endpoint, and therefore are less specific and may have lower power. To gain power, in this paper, we consider the problem as a two-dimensional multiplicity problem: one dimension concerns the multiple doses and the other dimension concerns the multiple endpoints. We propose procedures which consider the dose order to form the closure of the procedures and control the family-wise type I error rate in a strong sense. For this two-dimensional problem, numerical examples show that procedures proposed in this paper in general have higher power than the commonly used procedures (e.g. the regular Hochberg procedure) especially for comparing the higher dose to the control.

Development and validation for high selective quantitative determination of metformin in human plasma by cation exchanging with normal-phase LC/MS/MS

An assay based on cation exchange solid-phase extraction and liquid chromatography-tandem mass spectrometry (LC/MS/MS) has been developed for the quantitative determination of metformin in human plasma. The analytical method consists of cation exchange solid-phase extraction (VersaPlate CBA) without any further evaporation/dissolution steps and cation exchange-based HPLC separation (Capcell Pak SCX column) with a normal-phase gradient system followed by semi-micro LC/MS/MS in positive ion selected reaction monitoring mode using electrospray ionization. The method exhibited excellent performance in terms of selectivity, robustness, short run time (7 min/sample) and simplicity of sample preparation. The calibration range was 10-1000 ng/ml with 0.2 ml of plasma. Intra- and inter-day mean accuracies were within the ranges of 100.3-105.0% and 101.2-105.3%, respectively. Intra- and inter-day precisions were within the ranges of 0.8-1.9% and 1.5-8.6%, respectively. Mean absolute recovery was 67.0% for metformin. No apparent loss of metformin after extraction was observed in an autosampler at 10 degrees C for 24 h. Dilution of metformin by blank human plasma up to 20-fold was tested and revealed no impact on the results of determination. Furthermore, the method exhibited high selectivity, since no effect on metformin analysis was observed on comparison of samples with or without nateglinide and other agents in plasma. Results obtained with the method were also comparable to a published LC-UV method on cross-validation. This method can be applied to various clinical pharmacokinetic studies of metformin.

Thiazolidinediones and Insulin

The range of therapeutic modalities to treat type 2 diabetes mellitus has broadened in recent years. Biguanides and thiazolidinediones are the two currently available classes of anti-hyperglycemic agents with insulin-sensitizing properties. Thiazolidinediones, in particular, have received much attention, not only for the well documented hepatotoxicity of troglitazone that led to its removal from the market in 2000, but also for the emerging data that support the beneficial effects of the thiazolidinedione class of drugs on beta-cell rejuvenation and cardiovascular risk reduction. In the US, thiazolidinediones are indicated either as monotherapy or in combination with a sulfonylurea, metformin, or insulin in cases where diet, exercise, and a single drug fail. In contrast, the UK National Institute for Clinical Excellence included in its re-appraisal of 'glitazones' in August 2003 the continued exclusion from licensed use in the UK of combination therapy with thiazolidinediones and insulin. When added to insulin therapy, thiazolidinediones appear to effectively lower glucose levels and reduce insulin dosage in clinical trials involving individuals with poorly controlled type 2 diabetes. However, weight gain, hypoglycemia, and fluid retention pose problems in certain patients. The fluid retention may exacerbate or even precipitate congestive heart failure, which usually necessitates discontinuation of the drug. Risk stratification and careful management of patients at risk for heart failure, including those taking insulin concomitantly, allow healthcare providers to safely administer combination therapy with thiazolidinediones in patients with type 2 diabetes. Hepatic toxicity with currently available thiazolidinediones has been found to be minimal overall.

Diabetic dyslipidaemia: insights for optimizing patient management

BACKGROUND

Lipid abnormalities in people with diabetes are likely to play an important role in the development of atherogenesis. These lipid disorders include potentially atherogenic quantitative (increased triglyceride levels and decreased high-density lipoprotein-cholesterol [HDL-C] levels) and qualitative abnormalities of lipoproteins (changes in lipoprotein size, increase in triglyceride content of low-density lipoprotein (LDL) and HDL, glycation of apoproteins and increased susceptibility of LDL to oxidation). Guidelines from the two main diabetes organizations, the International Diabetes Federation and the American Diabetes Association, recommend the aggressive management of diabetic dyslipidaemia to reduce the risk of cardiovascular disease (CVD). Statins are the first choice pharmacological therapy to address diabetic dyslipidaemia due to their effectiveness at lowering LDL-C levels in patients with diabetes. Fibrates (peroxisome proliferator-activated receptor [PPAR]alpha ligands) target another aspect of dyslipidaemia by lower ing triglycerides (to a greater extent than statins) and raising HDL-C levels, especially when baseline levels are low. The PPARgamma agonist, pioglitazone appears to affect lipid metabolism by decreasing plasma triglycerides, increasing HDL-C and decreasing the number of small, dense atherogenic LDL particles.

SCOPE

This paper provides a review of the current literature (based on searches of MEDLINE and EMBASE from 1985 to 2005, inclusive) supporting the recommendations for the management of dyslipidaemia among patients with type 2 diabetes, including new strategies involving drug combinations that achieve good glycaemic and lipidaemic control that could potentially reduce the morbidity and mortality associated with type 2 diabetes.

Rosiglitazone improves insulin sensitivity and glucose tolerance in subjects with impaired glucose tolerance

OBJECTIVE

This study was designed to evaluate the effects of rosiglitazone (ROS) on insulin sensitivity, beta-cell function, and glycaemic response to glucose challenge and meal in subjects with impaired glucose tolerance (IGT).

METHODS

Thirty patients with IGT (ages between 30 and 75 years and BMI (body mass index) < or = 27 kg/m2) were randomly assigned to receive either placebo (n = 15) or ROS (4 mg/day) (n = 15). All participants underwent a 75-g oral glucose tolerance test (OGTT), meal test, and frequently sampled intravenous glucose tolerance test (FSIGT) before and after the 12-week treatment.

RESULTS

After 12 weeks of ROS treatment, there were significant increases in total cholesterol (TC) (4.25 +/- 0.22 vs 4.80 +/- 0.17 mmol/l, P < 0.001), high-density lipoprotein cholesterol (HDL-C) (1.25 +/- 0.07 vs 1.43 +/- 0.06 mmol/l, P < 0.05), and low-density lipoprotein cholesterol (LDL-C) (2.70 +/- 0.15 vs 3.37 +/- 0.17 mmol/l, P < 0.05) without changes in triglyceride concentration, TC/HDL-C and LDL-C/HDL-C ratio. Although the acute insulin response (AIR) to intravenous glucose and disposition index (measured as the ability of pancreatic beta-cell compensation in the presence of insulin resistance) remained unchanged, the insulin sensitivity (SI) and glucose effectiveness (SG) were remarkably elevated (0.38 +/- 0.06 vs 0.54 +/- 0.09 x 10(-5) min(-1)/pmol, P < 0.05; 0.017 +/- 0.002 vs 0.021 +/- 0.001 min(-1), P < 0.05, respectively) in the ROS group. The glucose, insulin, and c-peptide areas under curve (AUC) in response to OGTT and the glucose and insulin AUC during meal were significantly ameliorated in the ROS group. Five out of 15 (33%) and two out of 15 (13%) subjects treated with ROS and placebo, respectively, reversed to normal response during OGTT (P < 0.05).

CONCLUSION

Rosiglitazone treatment significantly improved insulin resistance and reduced postchallenge glucose and insulin concentrations in patients with impaired glucose tolerance without remarkable effects on beta-cell secretory function.

Predictive clinical parameters for therapeutic efficacy of rosiglitazone in Korean type 2 diabetes mellitus

This study evaluated the efficacy of rosiglitazone in non-obese and obese Korean type 2 diabetic patients of long duration. A total of 125 patients (M:F=44:81, mean age: 58.4+/-9.1 years, BMI: 24.2+/-2.7 kg/m2, duration of diabetes: 11.0+/-6.4 years) were randomly allocated to 12 weeks of rosiglitazone treatment (4 mg per day) or a control group. Responders were defined as patients who experienced fasting plasma glucose (FPG) reduction of >20% or HbA1c reduction of >1 (%). Rosiglitazone significantly improved glycemic control by reducing FPG and HbA1c (-3.4 mmol/l and -1.1%, P<0.001, respectively). It also significantly increased HOMA(beta-cell function) (+9.7, P<0.01) and QUICKI (+0.029, P<0.001), and decreased HOMA(IR) (-1.73, P<0.001). Females and those with higher waist-hip ratio made up a greater portion of rosiglitazone-responders. Responders (45 patients, 75%) also showed significantly higher FPG, HbA1c, systolic blood pressures, fasting insulin levels and HOMA(IR), and lower QUICKI than nonresponders. Among these parameters of responders, waist-hip ratio of non-obese subgroup, initial glycemic control of obese subgroup, and systolic blood pressure of both subgroups lost their significance after subdivision analysis. However, the baseline HOMA(IR) and QUICKI were significantly correlated with the response rate to rosiglitazone. Moreover, in multiple logistic regression analysis, HOMA(IR) and QUICKI retained their significance as the independent predictors. Even in Korean type 2 diabetic patients of long duration but with relatively preserved beta-cell function, rosiglitazone improved glycemic control, insulin sensitivity, and beta-cell function. In this ethnic group, female gender, central obesity, and especially severe insulin resistance were identified as predictive clinical parameters of rosiglitazone-responders.

The effects of rosiglitazone on fatty acid and triglyceride metabolism in type 2 diabetes

AIMS/HYPOTHESIS

We investigated the effects of rosiglitazone on NEFA and triglyceride metabolism in type 2 diabetes.

METHODS

In a double-blind, placebo-controlled, cross-over study of rosiglitazone in diet-treated type 2 diabetic subjects, we measured arteriovenous differences and tissue blood flow in forearm muscle and subcutaneous abdominal adipose tissue, used stable isotope techniques, and analysed gene expression. Responses to a mixed meal containing [1,1,1-(13)C]tripalmitin were assessed.

RESULTS

Rosiglitazone induced insulin sensitisation without altering fasting NEFA concentrations (-6.6%, p=0.16). Postprandial NEFA concentrations were lowered by rosiglitazone compared with placebo (-21%, p=0.04). Adipose tissue NEFA release was not decreased in the fasting state by rosiglitazone treatment (+24%, p=0.17) and was associated with an increased fasting hormone-sensitive lipase rate of action (+118%, p=0.01). Postprandial triglyceride concentrations were decreased by rosiglitazone treatment (-26%, p<0.01) despite unchanged fasting concentrations. Rosiglitazone did not change concentrations of triglyceride-rich lipoprotein remnants. Adipose tissue blood flow increased with rosiglitazone (+32%, p=0.03). Postprandial triglyceride [(13)C]palmitic acid concentrations were unchanged, whilst NEFA [(13)C]palmitic acid concentrations were decreased (p=0.04). In muscle, hexokinase II mRNA expression was increased by rosiglitazone (+166%, p=0.001) whilst the expression of genes involved in insulin signalling was unchanged. Adipose tissue expression of FABP4, LPL and FAT/CD36 was increased.

CONCLUSIONS/INTERPRETATION

Rosiglitazone decreases postprandial NEFA and triglyceride concentrations. This may represent decreased spillover of NEFAs from adipose tissue depots. Decreased delivery of NEFAs to the liver may lead to lowered postprandial triglyceride concentrations. Upregulation of hexokinase II expression in muscle may contribute to insulin sensitisation by rosiglitazone.

Addition of rosiglitazone to glimepirid and metformin combination therapy in type 2 diabetes

The study was planned to determine the efficacy and safety of adding rosiglitazone to a combination of glimepiride and metformin therapy with insufficiently controlled type 2 diabetes. This was an open-label study with a follow-up period of 26 weeks. Thirty patients were taking 3 mg glimepiride two times and 850 mg metformin two times per day. Patients were told to take one rosiglitazone 4 mg tablet before breakfast additionally. The primary efficacy measure was the mean change in HbA1c from baseline to the end of the study. Secondary efficacy parameters included the mean changes from baseline to the end of the study in fasting plasma glucose (FPG) and insulin levels, as well as total cholesterol, HDL-C, LDL-C, triglycerides, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Mean HbA1c levels decreased significantly from 7.54 +/- 0.9% to 6.57 +/- 0.7% (p < 0.001) at 26th week. FPG levels fell from 169.39 +/- 37.8 mg/dl to 135.69 +/- 28.0 mg/dl (p < 0.001), respectively. Insulin levels decreased from 19.60 +/- 9.8 U/L to 14.66 +/- 11.6 U/L (p = 0.026) at 26th week. No one experienced elevations of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels greater than 2.5 times the upper limit of the reference range. This study confirms that the addition of rosiglitazone (4 mg/day) to sulphonylurea and metformin treatment for patients with type 2 diabetes improves glycemic control, is safe, and generally well tolerated.

Thiazolidinediones: a review of their mechanisms of insulin sensitization, therapeutic potential, clinical efficacy, and tolerability

The thiazolidinediones (TZDs) rosiglitazone and pioglitazone are newer additions to the antidiabetic armamentarium and are indicated for the treatment of type 2 diabetes mellitus (T2DM) in the United States. The TZDs are peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists that provide clinically effective glycemic control and unique pharmacologic effects on multiple risk factors for T2DM-related morbidity, including improvement of insulin sensitivity and endothelial dysfunction, reduction of blood pressure, and amelioration of dyslipidemia. Weight gain and fluid retention occur with TZD therapy, especially when they are administered in higher doses and in combination with insulin. Although fluid retention associated with the use of TZDs is generally mild and reversible, these agents should not be used in patients with New York Heart Association Class III or IV heart failure symptoms. The findings of ongoing, long-term, prospective studies will clarify the role of the TZDs in the treatment of T2DM, particularly in terms of the durability of improvements in glycemic control, insulin sensitivity, pancreatic beta- cell function, and cardiovascular health.

Rosiglitazone, but not glyburide, reduces circulating proinsulin and the proinsulin:insulin ratio in type 2 diabetes

An elevation in the ratio of proinsulin (PI) to immunoreactive insulin (IRI) is inversely related to beta-cell function in type 2 diabetes, and increased PI is an independent risk factor for coronary heart disease. An objective of the present studies was to assess the effects of the thiazolidinedione insulin sensitizer, rosiglitazone, on indirect markers of beta-cell function and cardiovascular risk in people with type 2 diabetes by measuring plasma PI and the PI:IRI ratio. Parameters of insulin processing, including plasma PI and PI:IRI ratios, were determined in type 2 diabetes patients enrolled in two randomized double-blind studies comparing the effects of rosiglitazone (4 or 8 mg/d) with placebo (study 1, 26-wk treatment) or the sulfonylurea glyburide (study 2, 52-wk treatment). Treatment with rosiglitazone for 26 wk (study 1) produced significant dose-dependent decreases in both plasma PI concentrations (18-29%) and the PI:IRI ratio compared with baseline (7-14%) and placebo (19-29%) (P < 0.001). A significant increase in the PI:IRI ratio in placebo-treated patients occurred (P < 0.001). In study 2, rosiglitazone also significantly reduced both plasma PI and the PI:IRI ratio compared with baseline (P < 0.001). In contrast, glyburide significantly increased both plasma PI (45%; P < 0.001) and the PI:IRI ratio (10%) (P < 0.05 vs. baseline). These results show that rosiglitazone and glyburide have differential effects on absolute PI levels and the PI:IRI ratio in people with type 2 diabetes.

[The place of thiazolidinediones in the treatment of type 2 diabetes]

SUPPLEMENTARY ORAL ANTIDIABETICS: Thiazolidinediones or glitazones are a new class of oral antidiabetics, the effects on blood sugar control of which are mediated by the sensitivity of the peripheral tissue to the effect of insulin. Hence, their effect is complementary to that of the insulin secreting agents and that of metformin, which acts by blocking the hepatic production of glucose. OTHER BENEFICIAL EFFECTS: Other than their effect on blood glucose, thiazolidinediones have a favorable influence upon the cardiovascular risk factors or markers such as blood pressure, C-reactive protein and metalloproteinase-9. They also appear to induce long term preservation of the beta-cell capital. Principle side effects are salt-water retention with a risk of decompensation of a pre-existing heart failure and weight gain with regard to the subcutaneous adipose tissue, without deleterious effects on blood glucose control.

Treatment of insulin resistance in diabetes mellitus

Insulin resistance is a condition in which the glycemic response to insulin is less than normal. The change in insulin sensitivity leads to several sets of responses. One set effects the beta cell and leads to its accelerated destruction and the development of diabetes mellitus. The other set generates a series of nontraditional cardiovascular risk factors that result in accelerated atherosclerosis. Both of these sets of responses may have impacts on other tissues such as the nervous system. Insulin resistance is probably the result of increased visceral adiposity with increased release of free fatty acids and cytokines and a decreased release of adiponectin. Treatment of insulin resistance and its associated abnormalities can be achieved by lifestyle modification which results in weight loss, by drugs that reverse the abnormal adipocyte effects, by drugs that improve insulin sensitivity at the level of the liver and by anti-inflammatory agents that block activation of the nuclear factor kappa B cascade.

Severe hypo-alpha-lipoproteinemia during treatment with rosiglitazone

Thiazolidinedione drugs are in widespread use for the treatment of type 2 diabetes. In addition to improving insulin sensitivity, they generally result in a modest elevation of plasma HDL cholesterol. We report three patients, all of whom had preexisting diabetic dyslipidemia, who showed a profound reduction in plasma HDL cholesterol and apolipoprotein AI levels soon after the initiation of rosiglitazone therapy. In all three patients, HDL cholesterol levels returned to normal following drug withdrawal. The fact that this phenomenon was not seen in >1,400 patients studied in clinical trials indicates that it is likely to be rare and idiosyncratic. Until the frequency of this adverse reaction is clearer, it would seem advisable to ensure that plasma HDL cholesterol is documented before and rechecked after commencement of thiazolidinedione therapy.

Effect of rosiglitazone versus insulin on the pancreatic beta-cell function of subjects with type 2 diabetes

OBJECTIVE

In a previous study, we found observational evidence of improvement in beta-cell function when rosiglitazone was added to a failing oral antihyperglycemic regimen consisting of sulfonylureas and metformin. To confirm our previous observations, we designed and performed a prospective, randomized, and controlled study.

RESEARCH DESIGN AND METHODS

A total of 17 subjects with type 2 diabetes, inadequately controlled on a maximized oral antihyperglycemic double regimen of glimepiride and metformin, were randomized to the addition of rosiglitazone or insulin to their treatment regimens for a period of 6 months. At baseline and at 6 months, the following were performed: measurement of fasting plasma glucose, fasting proinsulin, and insulin levels; frequently sampled intravenous glucose tolerance test; and glucagon stimulation test for C-peptide.

RESULTS

Nine subjects were randomized to the addition of 8 mg rosiglitazone, and eight subjects were randomized to the addition of one injection of insulin (premixed 70/30) before their evening meal. The treatment groups were well matched for age, duration of diabetes, and BMI. Most important, the HbA(1c) was well matched between groups before treatment (8.7 +/- 0.3 and 9.0 +/- 0.3%; NS) and at the end of the 6 months (7.8 +/- 0.5 and 7.8 +/- 0.3%; NS). After 6 months, at the end of the study, there was a significant improvement in acute insulin response to glucose in the rosiglitazone group (+15.3 microIU x ml(-1) x 10 min(-1); P < 0.001) that led to an increase in the disposition index from 0.18 at baseline to 4.18 at 6 months (P = 0.02). Furthermore, at the end of the study, the proinsulin-to-insulin ratio had decreased in the rosiglitazone group by 36% (P = 0.03) but did not change significantly in the insulin treatment group.

CONCLUSIONS

Rosiglitazone, but not insulin, induced a recovery of pancreatic beta-cell function, as evidenced by the restoration of the first-phase insulin response to glucose, improvement in the disposition index, and a decrease in the proinsulin-to-insulin ratio in subjects with type 2 diabetes in whom oral antihyperglycemic therapy failed. This improvement was independent of the correction of glucotoxicity.

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

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

The combination oral and nutritional treatment of late-onset diabetes mellitus (CONTROL DM) trial results

OBJECTIVE

To examine the effect of short-term improvements in glycaemic control on brachial artery endothelial function as a marker of cardiovascular health.

METHODS

Persons with Type 2 diabetes who were poorly controlled on oral therapy were randomly assigned to monotherapy with repaglinide or combination therapy with repaglinide plus metformin. Brachial artery flow-mediated vasodilation was assessed by ultrasonography at randomization and following 16 weeks of therapy. The primary outcome was change in brachial artery endothelial function from baseline. Comparison of randomized groups was a secondary aim.

RESULTS

Eighty-six participants were randomized, and 83 were followed to study completion. Post occlusion brachial artery vasodilation was 3.74% at baseline and 3.82% following 16 weeks of therapy (P = 0.77). The treatment effect was 0.08% (95% CI: -0.48%, 0.64%). No difference was seen between treatment groups (P = 0.69). Overall, A1C was reduced from 8.3% to 7.0%, with a greater reduction in the combination therapy group (from 8.4% to 6.7%) than in the monotherapy group (from 8.3% to 7.3%, p for difference between groups = 0.01). Statistically significant reductions were observed in fasting glucose, and plasminogen activator inhibitor-1. Statistically significant increases were observed for fasting insulin, uric acid, weight and BMI.

CONCLUSIONS

Brachial artery endothelial function was not influenced by short-term improvements in glycaemic control. The CONTROL DM group was successful in lowering A1C. Future research should explore more intensive and longer-lasting improvements in glycaemic control on endothelial function. Some data previously published in abstract form (Diabetes 2001; 50 (Suppl. 2): A217).

Approach to the management of diabetic patients with heart failure: role of thiazolidinediones

Diabetes mellitus is a chronic, progressive disease that results in microvascular and macrovascular complications. Patients with diabetes are at high risk for developing heart failure, and the prevalence of diabetes in patients with heart failure ranges from 24% to 44%, with an estimated 1 to 2 million individuals in the United States having both diabetes and heart failure. Patients with diabetes and heart failure are at increased risk for mortality. Primary treatment goals in diabetes include restoration and maintenance of normoglycemia, avoidance of diabetic complications, and prevention of cardiovascular events. The range of therapeutic options for glycemic control has been extended with the introduction of thiazolidinediones (TZDs) used as monotherapy or in combination with other oral antidiabetic medications or insulin. TZDs decrease plasma insulin levels, improve endothelial function, decrease vascular inflammation, and decrease C-reactive protein levels, effects that are potentially beneficial in patients with heart failure. Weight gain and peripheral edema are recognized side effects of these drugs, particularly when used in combination with insulin. Although health care providers should be aware of the potential risk of worsened heart failure when TZDs are used in patients with diabetes and heart failure, these agents may be considered for use in patients with New York Heart Association class I and II heart failure when appropriate monitoring can be provided. Prospective clinical trials are currently under way to further define the cardiovascular safety and efficacy of TZDs in diabetic patients with heart failure.

Targeting insulin resistance and beta-cell dysfunction: the role of thiazolidinediones

Insulin resistance and beta-cell dysfunction are fundamental defects that contribute to the development of type 2 diabetes, and as such are targets for primary prevention of disease progression. The two parameters are linked by several factors, including glucotoxicity and lipotoxicity, and recent research has enlightened understanding of the molecular mechanisms underlying the development and progression of the disease. Historically, type 2 diabetes has been managed by controlling hyperglycemia, using agents that increase insulin levels or reduce hepatic glucose production, as exemplified by the United Kingdom Prospective Diabetes Study. The thiazolidinediones control hyperglycemia by targeting the fundamental defects of the disease, and have shown well-documented improvements in insulin sensitivity and beta-cell function, both in monotherapy and in combination with other oral antidiabetic agents. TRoglitazone In the Prevention Of Diabetes (TRIPOD) has demonstrated the potential for thiazolidinediones to delay progression to type 2 diabetes. Prospective studies such as Diabetes REduction Approaches with ramipril and rosiglitazone Medications (DREAM) are currently evaluating the long-term effects of thiazolidinediones on metabolic status and disease progression.

Avandamet: combined metformin-rosiglitazone treatment for insulin resistance in type 2 diabetes

Insulin resistance is a major endocrinopathy underlying the development of hyperglycaemia and cardiovascular disease in type 2 diabetes. Metformin (a biguanide) and rosiglitazone (a thiazolidinedione) counter insulin resistance, acting by different cellular mechanisms. The two agents can be used in combination to achieve additive glucose-lowering efficacy in the treatment of type 2 diabetes, without stimulating insulin secretion and without causing hypoglycaemia. Both agents also reduce a range of atherothrombotic factors and markers, indicating a lower cardiovascular risk. Early intervention with metformin is already known to reduce myocardial infarction and increase survival in overweight type 2 patients. Recently, a single-tablet combination of metformin and rosiglitazone, Avandamet, has become available. Avandamet is suitable for type 2 diabetic patients who are inadequately controlled by monotherapy with metformin or rosiglitazone. Patients already receiving separate tablets of metformin and rosiglitazone may switch to the single-tablet combination for convenience. Also, early introduction of the combination before maximal titration of one agent can reduce side effects. Use of Avandamet requires attention to the precautions for both metformin and rosiglitazone, especially renal, cardiac and hepatic competence. In summary, Avandamet is a single-tablet metformin-rosiglitazone combination that doubly targets insulin resistance as therapy for hyperglycaemia and vascular risk in type 2 diabetes.

Outcomes of initiation of therapy with once-daily combination of a thiazolidinedione and a biguanide at an early stage of type 2 diabetes

CONTEXT

Utilization of the biguanide metformin and a thiazolidinedione (TZD) with new onset diabetes has the benefit of lowering A1cs into the normal range without the problem of severe hypoglycaemia.

OBJECTIVE

To assess the effectiveness of once-daily combined metformin and TZD therapy compared with other therapeutic regimens typically utilized at later stages of type 2 diabetes.

METHODS

A random chart review of 300 type 2 diabetic patients and extraction of data for body mass index (BMI), duration of diabetes and C-peptide and A1c was performed. In the 210 type 2 diabetic subjects in whom this information was currently available, the data were analysed.

RESULTS

Eighty-six patients on once-daily metformin and rosiglitazone had an average A1c of 6.2% (group A), and 58 subjects on triple therapy (metformin, rosiglitazone and glimepiride) (group B) had an average haemoglobin A1c (HbA1c) of 6.9%. The 22 subjects on one injection of insulin per day in addition to triple therapy (group C) had an average HbA1c of 7.6%, and the 44 subjects on more than one insulin injection per day plus metformin and/or rosiglitazone (group D) had an average HbA1c of 8.3%. HbA1cs below 7.0% were found in 91.9% of group A, 21.7% of group B, 36.4% of group C and 56.8% of group D. HbA1cs below 6.5% were found in 78.2% in group A, 15.5% in group B, 22.7% in group C and 31.8% in group D. HbA1cs below 6.0% were found in 41.9% in group A, 6.9% in group B, 9.1% in group C and 13.6% in group D. On univariate analyses, the HbA1c was positively associated with the duration of diabetes and the BMI and negatively associated with random C-peptide levels. Alternatively, on multiple regression analysis, there was no statistical correlation between the duration of diabetes or BMI with the HbA1c. However, there was a strong statistical correlation between the random C-peptide level and the HbA1c (p = 0.002).

CONCLUSION

Early initiation of therapy for type 2 diabetes with a once-daily combination of metformin and rosiglitazone provides the greatest opportunity to achieve A1cs within the normal range. The level of achieved glycaemic control is not dependent on the number or potency of the therapies utilized but is dependent on the level of endogenous insulin production. The use of a TZD as part of initial therapy of type 2 diabetes with its documented ability to preserve or improve beta-cell function has the potential to achieve prolonged normoglycaemia in the type 2 diabetic patient.

The stepwise approach to the management of type 2 diabetes

As the prevalence of type 2 diabetes continues to increase worldwide, there is an enhanced need for effective disease management. Type 2 diabetes is managed through a stepwise program of intensive therapy that consists of lifestyle modifications and sequential addition of oral antihyperglycemic agents and insulin as necessary. Successful implementation of this approach lessens the microvascular complications of the disease and promotes a lifestyle that may reduce macrovascular complications and comorbidities. Because of the progressive pancreatic beta-cell failure that causes hyperglycemia in type 2 diabetes, many people with type 2 diabetes will ultimately require insulin for disease management. Insulin may be used alone or in combination with oral agents to achieve glycemic control with a minimum of side effects. Although disease management regimens must be tailored to the needs of the individual with type 2 diabetes, the health care provider should always employ an aggressive, treat-to-target strategy to lower hyperglycemia and lessen diabetes-related risk factors.

Hormone therapy impairs endothelial function in postmenopausal women with type 2 diabetes mellitus treated with rosiglitazone

Diabetes and ovarian senescence are associated with impaired endothelial function and altered arterial mechanical properties. Alterations in normal vascular structure and functioning are the primary cause of mortality and morbidity with type 2 diabetes. Similarly, after menopause, women experience an increase in the rate of cardiovascular disease. Thiazolidinediones have exhibited a number of antiatherogenic actions in populations with type 2 diabetes. The effect of thiazolidinediones in combination with hormone therapy (HT) in postmenopausal women is, however, unknown. To assess whether HT (transdermal estradiol 50 microg and micronized progesterone (100 mg/d) affects vascular function, 21 women receiving rosiglitazone were randomly assigned to receive HT or placebo for 12 wk in a double-blind crossover design. Measures of glycemic control, lipids, blood pressure, flow-mediated dilation, and distensibility index were undertaken at baseline and after each treatment. As a result, flow-mediated dilation was significantly reduced (15.3 +/- 3.8 to 6.6 +/- 1.6%, P = 0.02) with HT, whereas lipids, blood pressure, and distensibility index were unchanged. Placebo had no significant affect on any variables. Thus, the addition of HT to rosiglitazone treatment attenuates endothelial function without altering other cardiovascular risk factors. Caution should, therefore, be exercised when considering combined treatment with thiazolidinedione and HT.

Clinical interest of PPARs ligands

Cardiovascular disease is significantly increased in patients with metabolic syndrome and type 2 diabetes. Several factors such as chronic hyperglycemia, lipId abnormalities, endothelium dysfunction, inflammation, oxIdative stress, increased thrombosis and decreased fibrinolysis are likely to promote cardiovascular events in these patients. Because of positive effects on glucose homeostasis, lipId metabolism, proteins involved in all stages of atherogenesis, endothelium function, inflammation, thrombosis and fibrinolysis, PPARS alpha (fibrates) and PPARs gamma (glitazones) agonists are good candIdates to reduce cardiovascular disease, more precisely in subjects with metabolic syndrome or type 2 diabetes. PPARS alpha agonists (fibrates) are potent hypolipIdemic agents increasing plasma HDL-cholesterol and reducing free fatty acIds, triglycerIdes, LDL-cholesterol and the number of small dense LDL pArticles. Moreover, they reduce vascular inflammation and thrombosis, promote fibrinolysis and inhibit the production of the vasoconstrictor factor, endothelin-1, by the endothelium. They have been shown, in clinical trials, to reduce cardiovascular disease, more particularly in patients displaying lipId abnormalities typical of metabolic syndrome and type 2 diabetes (high triglycerIdes, low HDL-cholesterol). PPARS gamma agonists (glitazones) have not only beneficial effects on glucose homeostasis, by increasing insulin sensitivity and reducing blood glucose level but also on lipId metabolism by elevating plasma HDL-cholesterol, decreasing free fatty acIds and the number of small dense LDL pArticles, and for pioglitazone by reducing plasma triglycerIdes. Furthermore, they diminish vascular inflammation and vasoconstriction, inhibit monocyte chemotaxis, proliferation and migration of smooth muscle cells, in the vascular wall and decrease the production of adhesion molecules and metalloproteinases. PPARs gamma agonists (glitazones) have been shown to reduce the development of atherosclerotic lesions in rats. The potential clinical benefit of PPARs gamma agonists on the reduction of cardiovascular disease, in type 2 diabetic patients, will be specified by the ongoing intervention studies.