GLP-1 Suppression of Alpha Cell Secretion in T2DM

The incretin hormone glucagon-like peptide-1 (GLP-1) has known insulinotrophic and glucagonostatic properties. However, inpatients with type 2 diabetes mellitus (T2DM)it is shown, that the beta cell sensitivity towards GLP-1 is decreased, when comparing to healthy controls. Further, these patients have decreased GLP-1 response to a meal.

The aim of this study is to elucidate if the diabetic hyperglucagonemia, seen in these patients both during fasting and in a postprandial condition, is coursed by a decreased sensitivity to GLP-1 in the diabetic alpha cell.

Ten T2DM patients and ten matched healthy control subjects will be examined on two separate days. Day 1: increasing GLP-1 infusions and Day 2: saline. During both days plasma glucose (PG) will be clamped at fasting level (FPG).

Patients with T2DM will be submitted til a Day 3, here PG will be normalized over-night by an adjustable insulin infusion, on the following day the GLP-1 infusion of Day 1 will be repeated.

The hypothesis is that these patients have decreased alpha cell sensitivity to GLP-1 as is the case with the beta cell sensitivity. This decreased sensitivity, the investigators speculate, contributes the defect suppression og glucagon and thereby to the increased PG levels seen in T2DM. Further the investigators will elucidate if this sensitivity can be increased by normalizing the diabetic PG to a normal FPG level.