Influence of rosiglitazone treatment on β-cell function in type 2 diabetes: Evidence of an increased ability of glucose to entrain high-frequency insulin pulsatility

Thiazolidinediones have well-established insulin-sensitizing effects. Their impact on insulin secretion is less clarified. Consequently, we sought to determine potential effects of a thiazolidinedione (rosiglitazone) on the β-cell function. Twenty type 2 diabetic individuals were randomized to receive rosiglitazone (rosi) 4 mg twice daily or placebo (pla) for 13 wk. Before treatment and at the end of the treatment period, the patients underwent an iv glucose tolerance test (0.3 g/kg), a hyperglycemic (15 mmol/liter) clamp with arginine (5 g) stimulation, assessment of baseline high-frequency insulin pulsatility, and glucose-entrained insulin pulsatility (6 mg/kg·min every 10 min), and a hyperinsulinemic euglycemic clamp. Fasting plasma glucose was reduced (pla, 8.2 ± 2.1 vs. 8.8 ± 2.6 mmol/liter; rosi, 8.6 ± 7.1 vs. 7.1 ± 1.2 mmol/liter; P < 0.01), and insulin sensitivity was increased by rosiglitazone treatment (M value: pla, 5.3 ± 1.8 vs. 5.4 ± 1.6 mg/kg·min; rosi, 5.9 ± 2.2 vs. 7.4 ± 1.3 mg/kg·min; P =...