(RxWiki News) Type 2 diabetes patients have a high risk of heart disease. Recognizing the effects of diabetes medication on the heart may help change those risks — which might depend on gender.
Medications used to treat type 2 diabetes can keep blood sugar levels under control, and some are known to lower fat in the blood. Despite this, type 2 diabetes patients have a high risk of dying from heart-related causes.
Researchers recently reported on how diabetes medications affected the hearts of men and women.
These researchers found that metformin had a positive effect on heart function in women and a negative effect in men.
"Ask your pharmacist about the side effects of your diabetes treatment."
This research was conducted by senior author Robert J. Gropler, MD, from the Mallinckrodt Institute of Radiology at Washington University School of Medicine in St. Louis, Missouri, and his colleagues.
Death from heart disease is a risk for diabetes patients. According to the American Diabetes Association, “In 2004, heart disease was noted on 68 percent of diabetes-related death certificates among people aged 65 years or older. Adults with diabetes have heart disease death rates about 2 to 4 times higher than adults without diabetes.“
Diabetes medications help to control blood sugar (glucose), but some are also known to affect the fat content of blood. The researchers’ goal was to see how three diabetes medications affected the body and heart’s use of fatty acids and glucose in men and women.
The diabetes medication rosiglitazone (Avandia) is known to decrease fatty acids. Excess fatty acids can increase heart disease risk. Lovaza, another diabetes medication containing omega-3 fish oil, lowers triglycerides. Triglycerides are another type of fat found in blood that can increase heart disease risk. Metformin has little effect on fatty acids or triglycerides.
A total of 78 patients with type 2 diabetes were involved in this study.
These patients were either given metformin alone, metformin plus Avandia or metformin plus Lovaza. Participants had PET scans to assess heart oxygen and blood flow, as well as glucose and fatty acid uptake and use by the heart and whole body. Blood tests measured blood sugar and free fatty acids and EKGs (measures the heart's electrical activity) were done to measure heart function.
Women treated with metformin showed no change in heart or whole body use of fatty acids.
Men showed a decreased use of fatty acid by the whole body, but an increase in fatty acid use by the heart. Men also showed a decrease in glucose use by the heart.
The researchers did not see a difference in the whole body or heart uptake or use of glucose or fatty acids in either men or women who took metformin plus Lovaza.
Women given metformin plus Avandia had a significant decrease in plasma glucose compared to their blood glucose at the start of the study.
These women given metformin plus Avandia also had a decrease in fatty acid in the blood and a decrease in fatty acid use by the heart.
Men in this study did not show these changes, but did have higher triglycerides and higher high-density lipoprotein fat in their blood than when they started the study.
The researchers speculated that their study helps explain why these changes were not seen in other research where data from men and women were not looked at separately. When data was analyzed from groups that combined men and women, these results were not seen.
They concluded that it is very important to look at the effect of glucose medication on the heart and to look at men and women separately.
In a press release, Dr. Gropler said, “Instead of making heart metabolism more normal in men, metformin alone made it worse, looking even more like a diabetic heart. But in women, metformin had the desired effect — lowering fat metabolism and increasing glucose uptake by the heart.”
Two study subjects had reactions during the study and withdrew. One had been taking metformin alone and one had been taking metformin and Avandia.
Because of an increased heart and blood vessel disease warning by the Food and Drug Administration (FDA) on Avandia, the researchers stopped that part of the study early. The Avandia group ended up with fewer study participants in it and the authors noted that this was a limitation of the study. Another limitation of the study was that there were only 23-28 patients in each study group, so variations between people made the data harder to interpret.
This research was published in the December issue of the American Journal of Physiology - Heart and Circulatory Physiology.
Funding for this research came from the National Institutes of Health. The research team did not disclose any conflicts.