Repaglinide versus metformin in combination with bedtime NPH insulin in patients with type 2 diabetes established on insulin/metformin combination therapy

Abstract

Objective: To compare the effect on glycemic control and weight gain of repaglinide versus metformin combined with bedtime NPH insulin in patients with type 2 diabetes.

Research design and methods: A total of 80 subjects treated with 850 or 1,000 mg t.i.d. metformin combined with bedtime NPH insulin were randomized to 13 weeks of open-label treatment with 4 mg t.i.d. repaglinide (n = 39) or metformin (dose unchanged) (n = 41). Insulin dose was titrated at the clinician's discretion, aiming for a fasting blood glucose (FBG) < or =6.0 mmol/l.

Results: Baseline age, diabetes duration, insulin requirement, weight, BMI, FBG, and HbA(1c) (Diabetes Control and Complications Trial-aligned assay, normal range 4.6-6.2%) were similar. Glycemic control improved (nonsignificantly) with insulin/metformin by (mean) 0.4%, from 8.4 to 8.1% (P = 0.09) but deteriorated with insulin/repaglinide by (mean) 0.4%, from 8.1 to 8.6% (P = 0.03; P = 0.005 between groups). Weight gain was less with insulin/metformin: 0.9 +/- 0.4 kg (means +/- SE) (P = 0.01) versus 2.7 +/- 0.4 kg (P < 0.0001) (P = 0.002 between groups). The Diabetes Treatment Satisfaction Questionnaire score (potential range 0 [minimum] to 36 [maximum]) increased from 32.4 +/- 0.8 to 34.1 +/- 0.5 (P = 0.01) with insulin/metformin but decreased from 32.5 +/- 0.9 to 29.1 +/- 1.3 (P < 0.002) with insulin/repaglinide.

Conclusions: Combined with bedtime NPH insulin, metformin provides superior glycemic control to repaglinide with less weight gain and improved diabetes treatment satisfaction.