Background: Diabetic patients are considered less suitable than nondiabetic patients for beta-blocker therapy because of the risk for worsened glucose and lipid metabolism and more severe hypoglycemic attacks.
Objective: To compare the metabolic and cardiovascular effects of carvedilol with those of atenolol in diabetic patients with hypertension.
Design: Randomized, double-blind, 24-week trial.
Setting: University hospital clinic.
Patients: 45 patients with non-insulin-dependent diabetes mellitus and hypertension.
Intervention: After a 4- to 6-week run-in period during which placebo was given in a single-blind manner, patients were randomly assigned to carvedilol or atenolol.
Measurements: An oral glucose tolerance test; assessment of insulin sensitivity and hormonal responses to insulin hypoglycemia; and assessment of lipid levels, blood pressure, left ventricular mass, and lipid peroxidation.
Results: Changes in systolic and diastolic blood pressure and left ventricular mass index were similar with carvedilol and atenolol (P > 0.2). Fasting plasma glucose and insulin levels decreased with carvedilol and increased with atenolol. Responses to carvedilol were greater than those to atenolol, as follows: increase in total glucose disposal, 9.54 mumol/kg of body weight per minute (95% CI, 7 to 11.9 mumol/kg per minute); decrease in plasma glucose response to oral glucose, 61 mmol/L x 180 minutes (CI, -101 to -21 mmol/L x 180 minutes); decrease in insulin response to oral glucose, 6.2 nmol/L x 180 minutes (CI, -9.8 to -2.6 nmol/L x 180 minutes); decrease in triglyceride level, 0.56 mmol/L (CI, -0.75 to -0.37 mmol/L; P < 0.001); increase in high-density lipoprotein cholesterol level, 0.13 mmol/L (CI, 0.09 to 0.17 mmol/L; P < 0.001); and decrease in lipid peroxidation, 0.25 mumol/L (CI, -0.34 to -0.16 mumol/L).
Conclusions: By improving glucose and lipid metabolism and reducing lipid peroxidation, carvedilol may offer advantages in patients with diabetes and hypertension.