THURSDAY, April 7 (HealthDay News) -- The commonly used oral diabetes drug metformin not only helps stabilize blood sugar levels, it also may offer protection against heart disease, researchers say.
In a study that included more than 100,000 residents of Denmark taking metformin or another group of oral diabetes medications called insulin secretagogues (ISs), researchers found that metformin and the IS drugs gliclazide and repaglinide had the lowest risk of cardiovascular disease and death.
"Some medications, such as metformin, gliclazide and repaglinide, are more effective in reducing cardiovascular risk than the other medications," said Dr. Tina Ken Schramm, a senior resident at Copenhagen University Hospital in Denmark.
Dr. Darren McGuire, co-author of an editorial accompanying the study, agreed and said the study's findings are likely an indication that metformin, gliclazide and repaglinide are protective.
In previous research, metformin has been shown to reduce the risk of major adverse cardiac events and death by about 40 percent compared to placebo, he said. That means other drugs would have to offer a great deal of protection to compare favorably, he noted.
"If you compare a good drug against a great drug, the good drug doesn't necessarily look so good. But, if you compared the good drug to a placebo, the cardiovascular risk would probably be neutral," said McGuire, an associate professor in the division of cardiology at the University of Texas Southwestern Medical Center at Dallas.
Both experts said metformin is the recommended first line of treatment for someone with type 2 diabetes, and this study's findings support that recommendation.
Results of the study were published online April 6 in the European Heart Journal.
Although insulin secretagogues are widely prescribed for type 2 diabetes -- either alone or in combination with metformin -- information on their long-term cardiovascular effects is lacking, according to background information in the study.
To get a better idea of what impact, if any, these medications have on heart health, the researchers reviewed data on 107,806 people over 20 years old who lived in Denmark. All were taking an oral diabetes medication, such as metformin, glimepiride, gliclazide, glibenclamide (known as glyburide in the United States and Canada), glipizide, tolbutamide and repaglinide. Of this group, 9,607 people had experienced a previous cardiovascular event, such as a heart attack or stroke.
Compared to metformin, four of the drugs were more likely to be associated with an increased risk of all-cause mortality in people who hadn't had a previous cardiovascular event. The risk for glimepiride was 32 percent higher, while the risk was increased by 19 percent for glibenclamide. For glipizide the risk was 27 percent higher, and the risk of death was 28 percent higher for people taking tolbutamide versus metformin, according to the study. The risks were even higher in people taking these drugs who'd had a previous cardiovascular event.
The researchers also found that the risk of heart attack, stroke and cardiovascular death was higher in the people taking these medications.
The IS drugs gliclazide and repaglinide had risk profiles similar to metformin and didn't appear to be associated with an increased risk of death, heart attack or stroke.
"We demonstrated that for all outcomes, the ISs glimepiride, glibenclamide, glipizide and tolbutamide exhibited increased risk when compared to metformin, whereas there was no statistical difference in risk for gliclazide and repaglinide when compared to metformin," said Schramm.
McGuire cautioned that people shouldn't stop taking any type of diabetes medication on their own. If you're concerned, "have a discussion with your care provider," he said.
Learn more about oral diabetes medications from the American Diabetes Association.