San Diego, CA—Initiating treatment with a sulfonylurea was associated with a 33% greater likelihood of sustaining a cardiovascular event and a shorter time to sustaining a cardiovascular event compared with metformin in older adults with type 2 diabetes, according to a retrospective analysis presented at the 2011 Scientific Sessions of the American Diabetes Association. Older age and being male were associated with an increase in cardiovascular events.
“Both metformin and sulfonylureas are commonly used to treat type 2 diabetes mellitus. Metformin is associated with favorable cardiovascular outcomes, while sulfonylureas have been associated with an increased risk of cardiovascular events and death compared with metformin in some studies,” said Ying Qiu, PhD, an employee of Merck Sharpe & Dohme, Whitehouse Station, NJ.
The retrospective cohort study was based on a large electronic database of 8656 patients with type 2 diabetes from 2003 to 2008. Patients were aged 65 years on the index date and had been receiving treatment for at least 90 days. Patients with a history of cardiovascular events or preexisting hyperglycemia were excluded. Follow-up was a minimum of 2 years.
Each treatment arm of the study consisted of 4328 patients. At baseline, groups were matched for demographic and disease characteristics. The median age was 75 years; 48% of patients were female; the mean body mass index was 31 kg/m2; 4% were smokers; the mean hemoglobin A1c was 7.2%; the mean low-density lipoprotein cholesterol level was 10 mg/dL, mean high-density lipoprotein cholesterol level was 47 mg/dL, and mean total cholesterol was 184 mg/dL.
Cardiovascular events were observed in 11.6% of the metformin group versus 14.8% of the sulfonylurea group (P <.001). “This was driven largely by an increase in ischemic heart disease and congestive heart failure,” Dr Qiu said.
The time to a cardiovascular event was also significantly shorter with sulfonylureas than with metformin. At 2-year follow-up, patients receiving a sulfonylurea were 22% more likely to have an event than those receiving metformin. Three-year follow-up data confirmed this, Dr Qiu told listeners.
Limitations of this study are that it is a retrospective review, not a prospective clinical trial, and the design did not account for treatment discontinuation and subsequent therapies.