The NEPI antidiabetes study (NANSY). 1: short-term dose-effect relations of glimepiride in subjects with impaired fasting glucose

Abstract

Aim: NANSY is a randomised, placebo-controlled Swedish-Norwegian study which aims to include 2 x 1112 male and female subjects with impaired fasting glucose (IFG), to assess whether conversion to type 2 diabetes can be delayed by addition of sulphonylurea to dietary regulation and increased exercise. This pilot study was conducted to find the optimum dose of glimepiride in NANSY.

Methods: In a double blind trial in primary care 25 IFG subjects were in random order exposed to single doses and one-week treatments with 0 (placebo), 0.5, 1.0 and 2.0 mg glimepiride once daily. The optimum dose was assessed by measuring blood glucose during oral 75 g glucose tolerance test (OGTT), comparing fasting blood glucose, and the area under the blood glucose curve (AUC), and by monitoring hypoglycaemic events.

Results: With single doses, there was a clear dose-response relationship for the reduction in AUC, with a statistically significant difference only between placebo (mean 1981, 95% confidence intervals (CI) 1883-2078) and 2 mg glimepiride (mean 1763, 95% CI 1665-1861). However, following 1-week treatments, the only significant difference was between placebo (mean 1934, 95% CI 1856-2012) and 1 mg glimepiride (mean 1714, 95% CI 1637-1792). Correspondingly, the only statistically significant difference in fasting blood glucose day 7 was between placebo (5.87 mmol/l, 95% CI 5.68-6.05 mmol/l) and 1 mg glimepiride (5.42 mmol/l, 95% CI 5.21-5.62 mmol/l). Chemical hypoglycaemia was common but hypoglycaemic symptoms were rare and similar between the active doses, and easily countered by the subjects.

Conclusions: The sulphonylurea dose-effect curve may be bell-shaped, perhaps due to down regulation of sulphonylurea receptors during chronic exposure. Alternatively, the finding could be a rebound phenomenon, secondary to preceding hypoglycaemia. The optimum dose for NANSY was found to be 1 mg glimepiride.