Effects of insulin vs. glibenclamide in recently diagnosed patients with type 2 diabetes: a 4-year follow-up

Aim: To compare effects of early insulin vs. glibenclamide treatment on beta-cell function, metabolic control and quality of life (QL) in recently diagnosed patients with type 2 diabetes. Methods: Forty-nine patients with type 2 diabetes diagnosed 0-2 years before inclusion were randomized to two daily injections of premixed 30% soluble and 70% NPH insulin or glibenclamide at six diabetic clinics in Sweden. C-peptide-glucagon tests were performed yearly after 3 days of withdrawal of treatment. Results: Thirty-four patients completed 4 years of study. Daily dose of insulin was increased from 20.4 +/- 1.8 U at year 1 to 26.1 +/- 2.9 U at year 4 (p = 0.005). Glibenclamide dosage increased from 2.7 +/- 0.4 mg at year 1 to 4.5 +/- 0.8 mg at year 4 (p = 0.02). Weight increased more in insulin than in glibenclamide treated (+4.4 +/- 0.8 vs. +0.3 +/- 1.0 kg, p < 0.005). Following short-term withdrawal of treatment, the C-peptide responses to glucagon were significantly higher in the insulin vs. glibenclamide group at years 1 (p < 0.01) and 2 (p < 0.02). HbA1c improved identical during the first year but thereafter deteriorated in the glibenclamide group (p < 0.005 for difference at year 4). Ratios of proinsulin to insulin were higher during treatment in glibenclamide- vs. insulin-treated patients after year 2. QL after 4 years as measured by the MOS 36-item Short-Form Health Survey (SF-36) form was not significantly altered. Conclusions: In a 4-year perspective, beta-cell function deteriorated in both groups. However, deterioration occurred faster in the glibenclamide group, indicating that alleviating demands on secretion by insulin treatment is beneficial.