Beta-blockers have established value in treating heart failure. However, many physicians are hesitant to use beta-blockers in heart failure patients who have diabetes. This is mainly because they fear beta-blockers may exacerbate glucose intolerance.

About one-third of heart failure patients have diabetes mellitus. Dr. Fowler and colleagues wanted to know if there is evidence to justify concerns over using beta-blockers in these patients. They examined the effect of carvedilol versus placebo in patients who participated in the COPERNICUS trial.

Investigators in this trial randomized 2,289 patients with heart failure symptoms at rest or on minimal exertion to carvedilol or placebo. They stopped the trial early because carvedilol markedly improved survival.

That patient population included 589 diabetic and 1,700 non-diabetic patients. Dr. Fowler reported that both diabetic and non-diabetic patient groups had a similar improvement in clinical status, rate of hospitalization and survival.

Hazard ratios (treatment/placebo) for all-cause mortality were 0.65 for both diabetics and non-diabetics. Hazard ratios were also similar for composites of all-cause mortality and hospitalization.

Diabetics tolerated carvedilol well, according to Dr. Fowler. They had no excess risk of hyperglycemia or renal dysfunction. There was a low incidence of hypotension and presyncope in these patients.

Dr. Fowler said physicians should not fear that carvedilol treatment would harm diabetics. In fact, this treatment effectively reduces death and hospitalization in these patients.