Hypoglycemia Not Likely an Issue With Beta-Blockers

Question: There are so many studies touting the importance of beta-blockers in people with diabetes. I am concerned about hypoglycemia unawareness in these patients. How should I address this?

Answer: For many years beta-blockers have been underutilized in patients with diabetes because of several fears.

In patients with insulin-treated diabetes, some clinicians are concerned over the effect of beta-blockers reducing or eliminating the warning symptoms of hypoglycemia. Anthony H. Barnett, MD, and colleagues addressed this concern in a prospective study of 150 insulin-treated patients.¹ Fifty insulin-treated subjects taking beta-blockers were compared with 100 insulin-treated subjects not on beta-blockers.

The patients kept a diary recording all episodes of hypoglycemia and all warning symptoms. The incidence of loss of consciousness from hypoglycemia was the same in both groups and was not related to the dose of beta-blocker used. All symptoms of hypoglycemia were similar in both groups, with the exception of diaphoresis (perspiration), which was more common in the beta-blocker group. Diaphoresis is a dramatic symptom, and it makes patients aware of a sudden change in their blood glucose.

In another study, patients with diabetes on beta-blockers were given insulin infusions to drop their blood glucose and symptoms were recorded.² The patients on beta-blockers did not have hypoglycemic unawareness. They did have adrenergic symptoms at lower blood glucose levels than the control subjects who were not on beta-blockers, but their overall symptom scores were greater because of an increased perception of diaphoresis in the patients treated with beta-blockers.

In a retrospective cohort study, more than 13,000 patients with diabetes who were treated with either oral hypoglycemic drugs or insulin were studied as to whether antihypertensive agents predisposed them to serious hypoglycemic events.³ No class of antihypertensive medication (including beta-blockers) was found to predispose treated patients with diabetes to serious hypoglycemic events.

The theoretical concerns of hypoglycemia unawareness and blunted hypoglycemic response do not appear to be clinically important. Patients with diabetes treated with beta-blockers are no more likely to have serious hypoglycemic events than those not treated with beta-blockers.

The symptom of diaphoresis—which is more common in hypoglycemic patients on beta-blockers—may actually make these patients more aware of their hypoglycemia. Clinicians should feel comfortable prescribing beta-blockers in patients with diabetes. ▪