CHICAGO, Dec. 22 (Xinhua) -- Two drugs commonly prescribed to treat Type 2 diabetes carry a high risk of cardiovascular events such as heart attack, stroke, heart failure or amputation, according to a Northwestern Medicine (NU) study.

The two drugs, sulfonylureas and basal insulin, are commonly prescribed to patients after they have taken metformin, a widely accepted initial Type 2 diabetes treatment.

The observational study used data from 132,737 patients with Type 2 diabetes who were starting second-line treatment.

Some 60 percent of the patients nationwide who need a second-line drug are prescribed one of these two drugs, the study found. Yet, patients who take one of these two drugs, 36 percent more for sulfonylureas and twice as likely for basal insulin, are more likely to experience cardiovascular harm than those taking a newer class of diabetes drugs known as DPP-4 inhibitors.

"According to our findings, we only have to prescribe basal insulin to 37 people over two years to observe one cardiovascular event, such as a heart attack, stroke, heart failure or amputation," said lead author Matthew O'Brien, assistant professor of general internal medicine and geriatrics at NU Feinberg School of Medicine and a Northwestern Medicine physician. "For sulfonylureas, that number was a bit higher, 103 people. But when you apply these numbers to 30 million Americans with diabetes, this has staggering implications for how we may be harming many patients."

Physicians should consider prescribing newer classes of antidiabetic medications, such as GLP-1 agonists or liraglutide, SGLT-2 inhibitors or empagliflozin, and DPP-4 inhibitors or sitagliptin, more routinely after metformin, rather than sulfonylureas or basal insulin, the researchers suggest.

These drugs, however, are more expensive than the sulfonylureas.

This is the first study to compare how each of the six major second-line drugs impact cardiovascular outcomes in Type 2 diabetes patients taking a second diabetes medication.

The study was published Dec. 21 in JAMA Network Open.