Comparison of tolbutamide and metformin in elderly diabetic patients

In a randomized double-blind cross-over study the efficacy, metabolic effects, and acceptability of metformin were compared with tolbutamide in 20 diabetic patients aged between 65 and 95 years. No significant differences were noted after treatment in blood glucose control (fasting plasma glucose, metformin 9.1 +/- 2.8 mmol l-1, tolbutamide 8.3 +/- 2.8 mmol l-1; mean change, metformin +1.1 mmol l-1, tolbutamide +0.02 mmol l-1, p = 0.215), domiciliary blood glucose control, fasting insulin, lactate, cholesterol or triglyceride levels. There was a significant difference in weight change between the two treatments (on metformin -2.0 kg, from 63.2 +/- 11.8 to 61.2 +/- 12.3; on tolbutamide, +1.6 kg, from 61.4 +/- 11.1 to 63.0 +/- 12.3; p = 0.001). Initial gastro-intestinal side-effects occurred in 30% of patients with metformin. These were transient and responded to temporary reduction in treatment dosage. Metformin could not be distinguished from tolbutamide in elderly diabetic patients, except in that it was associated with weight loss.