Comparison of efficacy, secondary failure rate, and complications of sulfonylureas.

The data from three clinical trials are presented, comparing the efficacy of different sulfonylureas in the treatment of type II diabetes. In a multicenter study, gliclazide improved control in 49% of patients who had failed on other drugs. When five groups of type II diabetic patients were treated concurrently with five randomly allocated different sulfonylureas over 1 year, the percentage of patients achieving normal HbA1 levels was best with gliclazide (80%) and glibenclamide (74%), when compared with chlorpropamide (17%), glipizide (40%), and gliquidone (40%). Secondary failure rate over 5 years was assessed in 248 type II diabetic patients randomly allocated to three different sulfonylureas and found to be lowest with gliclazide (7%) compared with glibenclamide (17.9%): p < 0.1) and glipizide (25.6%: p < 0.005). The incidence of hypoglycemia was significantly higher with glibenclamide than with gliclazide (p < 0.05). The differences in efficacy and secondary failure rate between sulfonylureas may be related to the mechanism of insulin release from the beta-cell and the more physiological action of gliclazide could partly explain this. These trials suggest that gliclazide is a potent sulfonylurea with a low rate of secondary failure and a low incidence of side effects and may be a better choice in long-term sulfonylurea therapy.