Experts at Joslin Diabetes Center say that while the study results need to be confirmed with further research, the study could lead physicians to ask patients whether they have a history of type 2 diabetes in their family or are members of certain ethnic groups that are at high risk for diabetes. Physicians might one day make judgments about which blood pressuring lowering medication they prescribe based on the answers to those questions.

For years research has suggested that thiazide diuretics and beta-blockers commonly prescribed for high blood pressure and heart disease may promote development of type 2 (adult-onset) diabetes, but findings have been inconsistent. High blood pressure medications are used by more than 20 million adults in the US. Thiazide diuretics and beta-blockers are generally considered first-line agents for treating high blood pressure. An estimated 16 million Americans have diabetes, and many take these medications because they have, or are at risk for, cardiovascular complications such as heart attack, strokes, nerve damage, kidney disease, and more.

In the six-year Johns Hopkins' study, 12,550 adults ages 45-64 who did not have diabetes were studied. Those with high blood pressure who took beta-blockers had a 28 percent higher risk of eventually developing type 2 diabetes than did those who took no medication. In contrast, those who took one of the other types of drugs used to treat high blood pressure — thiazide diuretic, angiotensin-converting-enzyme (ACE) inhibitors or calcium-channel antagonists — were found to have no increased risk of developing diabetes.

Om Ganda, M.D., Senior Physician and lipids specialist at Joslin Diabetes Center in Boston, generally agrees with the authors' conclusion that concern about the risk of diabetes should not discourage doctors from prescribing beta-blockers for adults who do not have diabetes but who have hypertension. "Beta-blockers may not be the ideal treatment for all patients who have hypertension, however, particularly if they have an increased risk for diabetes," Dr. Ganda says. "On the other hand, beta-blockers have proven beneficial effects in reducing heart attacks and strokes in people with and without diabetes." Also, he adds, it is unclear what role the ethnic makeup of the study had on the outcome and exactly what type of beta-blockers were studied. "It's a 'Catch 22' situation for doctors," Dr. Ganda says. "But beta-blockers have saved many lives," he says.

Source: Joslin Diabetes Center.

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