Among patients with type 2 diabetes taking oral antidiabetes drugs, hypoglycemia is nearly 3 times more common with sulfonylurea treatment than with metformin use
Lactic acidosis, a concern raised in connection with metformin use, is rare with any treatment, the researchers report.
Dr. Christoph R. Meier, stated that “Metformin is a rather safe drug with a low absolute risk of lactic acidosis. “The risk of developing severe hypoglycemia is much higher in absolute terms for other drugs, particularly insulin and sulfonylureas, and this is much more relevant in clinical practice than the risk of lactic acidosis, which is a very rare outcome.”
Dr. Meier from University Hospital Basel, Switzerland and colleagues compared the risk of lactic acidosis and hypoglycemia associated with metformin, sulfonylureas, and other oral antidiabetes drugs in a study population of more than 50,000 type 2 diabetics.
The crude incidence of lactic acidosis was 3.3 per 100,000 person-years in metformin users, the authors report, compared with 4.8 per 100,000 person-years in sulfonylurea users. The actual numbers of cases were too small for formal statistical comparisons.
Hypoglycemia occurred at a substantially higher frequency among sulfonylurea users (110 cases per 100,000 person-years) than among metformin users (60 cases per 100,000 person-years), the researchers found.
Among patients not using insulin, sulfonylurea use was associated with a 2.79-fold greater risk of hypoglycemia than was metformin use.
The adjusted odds ratios were similar for men and women and for patients older and younger than 70 years.
“Our data seem to confirm that metformin does not increase the risk of lactic acidosis per se if patients are otherwise rather ‘healthy,'” Dr. Meier explained. “However, patients with an acute deterioration of their health status (e.g., due to a severe infection, a decrease in renal function, etc.) are at an increased risk, but the same holds true for users of other oral antidiabetics.”
“We are currently analyzing whether the relative risk of developing cancer differs in association with oral antidiabetic use,” Dr. Meier added. “There is evidence from animal models and research on human cell lines that metformin might inhibit growth of certain tumors, and we are currently investigating whether we find evidence for an altered risk among type 2 diabetics using various antidiabetic drugs.”
Diabetes Care 2008;31:2086-2091