Diabetes drugs affect hearts of men, women differently

WIDELY used treatments for type 2 diabetes have different effects on the hearts of men and women, even as the drugs control blood sugar equally well in both sexes.

In particular, , according to researchers at Washington University School of Medicine in St. Louis, the commonly prescribed diabetes drug metformin had positive effects on heart function in women but not in men, who experienced a shift in metabolism thought to increase the risk of heart failure.

“We saw dramatic sex differences in how the heart responds to the different therapies,” said senior author Robert J. Gropler, MD, professor of radiology. “Our study suggests that we need to better define which therapies are optimal for women with diabetes and which ones are optimal for men.”

The study* appears in the December issue of the American Journal of Physiology - Heart and Circulatory Physiology.

To the researchers’ knowledge, this is the first study to investigate sex differences in the heart’s response to diabetes treatments. In type 2 diabetes, the pancreas continues to make insulin, but the body can’t use it effectively to move glucose out of the blood and into the tissues. And for reasons that are not entirely clear, patients with diabetes are at higher risk for heart failure.

“It is imperative that we gain understanding of diabetes medications and their impact on the heart in order to design optimal treatment regimens for patients,” said Janet B. McGill, MD, professor of medicine and a study co-author who sees patients at Barnes-Jewish Hospital. “This study is a step in that direction.”

The investigators evaluated commonly prescribed diabetes drugs in 78 patients, who were assigned to one of three groups. Under McGill’s supervision, the first group received metformin alone; the second received metformin plus rosiglitazone (Avandia); and the third received metformin plus Lovaza, which is a kind of fish oil.

Janet B. McGill, MD, and Robert J. Gropler, MD, look through the PET scanner they and their colleagues used to study the heart’s response to common diabetes therapies. They found large differences in heart metabolism between men and women taking widely used diabetes drugs.

Metformin reduces glucose production by the liver and helps the body become more sensitive to insulin. Rosiglitazone also improves insulin sensitivity and is known to move free fatty acids out of the blood. Lovaza is prescribed to lower blood levels of triglycerides, another type of fat.

Importantly, Gropler noted that when they compared the three groups without separating men and women, no differences in heart metabolism were seen. But when the patients were separated by sex, the drugs had very different and sometimes opposite effects on heart metabolism, even as blood sugar remained well-controlled in all patients.

“The most dramatic difference between men and women is with metformin alone,” said Gropler, who also sees patients at Barnes-Jewish Hospital. “Our data show it to have a favorable effect on cardiac metabolism in women and an unfavorable one in men.”

The research suggests that these divergent responses in men and women may provide at least a partial explanation for the conflicting data surrounding some diabetes drugs. SpeNike