NEW YORK (Reuters Health) – New research shows that antidiabetes agents are not equal when it comes to cardiovascular risks and mortality.

According to a report in the December 4th Online First issue of BMJ, first and second generation sulfonylureas have a 24% to 61% excess risk for all cause mortality, and second generation sulfonylureas have an 18% to 30% excess risk of congestive heart failure, compared to metformin.

Pioglitazone, on the other hand, has 31% to 39% lower risk of all cause mortality relative to metformin, senior researcher Dr. Paul Elliott, from Imperial College London, and colleagues report.

Dr. Elliott’s group analyzed data from 91,521 adults with diabetes who were logged in the UK general practice research database from 1990 to 2005. During a mean follow-up of 7.1 years, 3588 first myocardial infarctions, 6900 incident cases of congestive heart failure, and 18,548 deaths occurred.

Still, the absolute risk of mortality or a cardiovascular event with any of these drugs is fairly small. For instance, during 2,842,504 drug treatment intervals, 1341 deaths of any cause were seen with first generation sulfonylureas, which equates to 1 death for every 2120 intervals. (An interval was defined as the period from the onset of a drug treatment until the onset of the next drug treatment, occurrence of “an event of interest,” or censorship.)

In addition to the differences uncovered between drug classes, the researchers also found some in-class differences. In particular, among thiazolidinediones, rosiglitazone had a 34% to 41% higher risk of all cause mortality relative to pioglitazone, although the risk was not significant in the adjusted model, and the thiazolidinediones were not associated with risk of myocardial infarction.

“The sulfonylureas, along with metformin, have long been considered the mainstay of drug treatment for type 2 diabetes,” the authors conclude. “Our findings suggest a relatively unfavorable risk profile of sulfonylureas compared with metformin.”

Their results also support recommendations of the American Diabetes Association and the International Diabetes Federation that support metformin as the initial treatment for type 2 diabetes.

Reference:
BMJ 2009;339:b4731.