What Is the Benefit of Increasing the Sulfonylurea Dose?

1 February 1993 | Volume 118 Issue 3 | Pages 169-172

Objective: To study the clinical benefit of increasing the dose of the sulfonylurea, glipizide, from 10 to 40 mg per day.

Design: A placebo-controlled, double-blind, cross-over study.

Setting: An outpatient clinic at the Helsinki University Hospital, Finland.

Patients: Twenty-three patients with noninsulin-dependent diabetes mellitus.

Methods: Patients were given glipizide in three different dose schedules for 3 months each: 10 mg in the morning or 10 mg or 20 mg in the morning and the evening. Glycemic control was followed by HbA_1c measurements and blood glucose monitoring at home. Beta cell function was assessed by measuring insulin responses to a test meal.

Results: Mean home-monitored blood glucose was 12.4 mmol/L during placebo treatment, and it was 9.6, 9.2, and 8.9 mmol/L after treatment with glipizide, 10, 20, or 40 mg, respectively. The levels of blood glucose and HbA_1c differed after all treatment groups from placebo (P < 0.001) but not among themselves. The insulin response to a test meal was greatest after 10 mg of glipizide and weakest after 40 mg/d (P = 0.02 compared with the 10-mg dose). All treatments stimulated insulin secretion more than placebo (P < 0.001).

Conclusions: Increasing the glipizide dose to more than 10 mg once daily produces little or no benefit and may reduce ß-cell function.

Author and Article Information

From Helsinki University Central Hospital, Helsinki, Finland; the University of Lund, Malmo, Sweden.
Requests for Reprints: Svante Stenman, MD, IV Department of Medicine, Helsinki University Central Hospital, 00170 Helsinki, Finland.
Acknowledgments: The authors thank Ms. Kirsi Laakkonen and Mr. Esa Laurila for technical and nursing work in the study.
Grant Support: By Pfizer Roerig New York, New York, and by the Sigrid Juselius Foundation and Finska Lakaresallskapet, Helsinki, Finland.