Diabetes Express Report^TM

Based on Data Presented at the American Heart Association Scientific Sessions 2004, November 7–10, 2004/New Orleans, Louisiana

Publication date: 2004-12-07

Achieving Hypertension Goals in Patients with Diabetes

This report was reviewed for medical and scientific accuracy by Barry H. Greenberg, MD, Professor of Medicine and Director, Heart Failure/Cardiac Transplantation Program, University of California in San Diego, San Diego, California

Expert Commentary

George L. Bakris, MD, FACP, FAHA, FCP, Professor, Departments of Preventive and Internal Medicine and Director, Hypertension Research Center, Rush University Medical Center, Chicago, Illinois

According to the results of the Glycemic Effects in Diabetes Mellitus: Carvedilol-Metoprolol Comparison in Hypertensives (GEMINI) trial presented at the American Heart Association Scientific Sessions 2004, the use of carvedilol (Coreg) in the presence of renin-angiotensin system blockade did not affect glycemic control and resulted in improvements in components of the metabolic syndrome when compared with metoprolol tartrate (Lopressor) in patients with type 2 diabetes and hypertension.^1,2 More specifically, carvedilol stabilized glycosylated hemoglobin A_1c (HbA_1c), improved insulin resistance, and slowed development of microalbuminuria compared with metoprolol. The results of GEMINI indicate that carvedilol offers a promising addition to currently utilized antihypertensive agents to safely and effectively reduce cardiovascular risk factors in hypertensive diabetic patients.

Hypertension substantially contributes to cardiovascular morbidity and mortality in patients with diabetes.³ Currently, over 11 million Americans have both diabetes and hypertension,³ a number that will likely continue to grow with the increasing prevalence of obesity. Aggressive management of cardiovascular risk factors such as blood pressure, HbA_1c, and microalbuminuria are critical to reducing the risk of myocardial infarction, stroke, and death.⁴ Unfortunately, target levels of risk parameters are reached by only a minority of diabetic patients. According to data from the National Health and Nutrition Examination Survey 1999-2000 (NHANES), "good control" of cardiovascular risk factors (defined as HbA_1c <7%, blood pressure <130/80, and total cholesterol <200 mg/dL) is only achieved by approximately 7% of adults.⁵

An average of 2 or more antihypertensive agents is required to reach the target blood pressure goal in patients with type 2 diabetes.³ Antihypertensive agents most commonly used in the diabetic population are those that inhibit the renin-angiotensin-aldosterone system, such as angiotensin-converting-enzyme (ACE) inhibitors and angiotensin II receptor blockers, which have proven beneficial effects on the micro- and macrovascular complications of diabetes as well as reducing cardiovascular morbidity and mortality.^6-8 Although beta-blockers have historically been avoided in patients with diabetes due to the worsening of glycemic control,^9,10 newer beta-blockers have demonstrated no effect on glycemic control and may actually reduce insulin resistance.¹¹ Moreover, beta-blockers have demonstrated clear benefit in cardiovascular risk reduction in patients with diabetes^12-14 and are included in treatment guidelines for the management of hypertension in patients with diabetes.¹⁵

This Diabetes Express Report^TMdescribes the use of beta-blockers in the treatment of hypertension among patients with diabetes with a focus on the results of the GEMINI trial.

Carvedilol Demonstrates Advantages in Patients with Diabetes: The GEMINI Trial

The GEMINI trial was a randomized, double-blind trial that compared 2 beta-blockers with different pharmacological profiles for their effects on glycemic and metabolic control in patients with diabetes and hypertension who were receiving concomitant ACE inhibitors or angiotensin receptor blockers. GEMINI tested the hypothesis that carvedilol, known to improve insulin sensitivity, was superior to metoprolol in maintaining glycemic control in the presence of renin-