Heart problems are a serious and common issue for patients with type 2 diabetes. Controlling diabetes might reduce their heart risks, but that protection might depend on the specific diabetes treatment.
Diet-only treatments and the diabetes medication metformin were linked to a lower chance of cardiovascular problems, such as heart attacks and strokes, among type 2 diabetes patients compared to insulin treatment, a new study found.
The study also showed that no other medication taken by itself or in combination with other therapies decreased the odds of having heart events or dying from these events compared to taking insulin alone.
Adam Ali Ghotbi, MD, from the Department of Clinical Physiology at Copenhagen University Hospital in Denmark, led a team of researchers that looked at how treatments used to lower blood sugar affected heart health and death rates in type 2 diabetes patients.
In patients with type 2 diabetes, the body contains too much blood sugar, or glucose, to be processed properly.
Though there are often no symptoms at first, type 2 diabetes can lead to more frequent infections that can heal slowly, fatigue and increased thirst and urination.
This study included 8,192 patients who were overweight and at an increased cardiovascular risk.
These patients were part of the Sibutramine Cardiovascular Outcomes Trial (SCOUT), which randomly assigned patients to take or not take the appetite suppressant sibutramine. Though the appetite suppressant is no longer available in the US, it can reduce adverse heart effects in high risk patients, according to the researchers.
For the current study, patients were categorized into one of several groups based on the treatment they took.
The treatments consisted of diet alone, metformin therapy, insulin therapy, sulfonylurea therapy, metformin with sulfonylurea and metformin with insulin.
The researchers tracked the time between patients starting the study and when they had a heart event, including heart attacks, nonfatal strokes, cardiac arrest or death.
Patients who controlled their diet alone decreased their chances of having a heart event by 35 percent compared to the other groups, the researchers found.
Taking metformin by itself decreased patients' chances of having a heart event by 26 percent. The medicine was also tied to a 27 percent decreased chance of dying.
Other medications taken alone or in combination were not significantly associated to adverse heart events or deaths, according to the researchers.
During the follow-up period, 905 patients experienced some heart event, and 708 participants died.
Age, chronic heart failure and hypertension (high blood pressure) were all linked with an increased chance of having a heart event.
"In conclusion, we demonstrated that compared with insulin [alone], treatment with metformin...was associated with decreased risk of cardiovascular events in obese type 2 patients with diabetes with known or increased risk of cardiovascular disease," the researchers wrote in their report.
The authors noted a few limitations of their study, including that they did know whether patients had any hypoglycemic events, or when blood sugar was too low. They also could not determine whether other ongoing body processes affected their results.
"A potential caveat to this study is the tendency of physicians to treat less severe type 2 diabetes with diet control or metformin alone," said David Edwards, MD, a cardiologist on the medical staff at The Heart Hospital Baylor Plano, part of Baylor Health Care System.
"Nonetheless, the other medications or insulin itself all increase circulating insulin, and increased insulin in this study had no clear benefit in the measured outcomes," said Dr. Edwards, who was not involved in this study.
The study, funded by Abbott Laboratories, was published online October 2 in the journal Diabetes Care.
Two of the authors served on the SCOUT steering committee and gave presentations sponsored by Abbott. No other conflicts of interest were reported.