Influence of Glucagon Inhibition in Relation to the Anti-Diabetic Effect of GLP-1 in Patients With Type 2 Diabetes Mellitus.

Incretinbased treatment of patients with type 2 diabetes mellitus (T2DM) has increasing interest. The incretin glucagon-like peptide-1 (GLP-1) stimulates beta-cells to increased secretion and production of insulin. Glucose sensitivity is enhanced, apoptosis inhibited - progression in disease is potentially stopped. The alpha-cell is also influenced by GLP-1 as infusion lowers plasmaglucose (PG) levels in patients with type 1 diabetes mellitus (T1DM) (C-peptide negative) by inhibition of glucagon and thereby decreased hepatic glucoseproduction (HGP). Further Vilsboll et al has proved normalization of the glacgonostatic effect of glucose in patients with T2DM. As an attempt to elucidate glucose-intolerance in patients with T2DM further Knop et al investigated the glucagonresponse to both oral glucose tolerance test (OGTT) and a following iso-glycemic clamp. He saw a sufficient suppression of glucagon when glucose was introduced intravenously but the suppression of glucagon was attenuated and delayed when glucose was given orally.

The aim of this study is to elucidate the glucose intolerance further. Due to the complex interactions and mutual feed-back regulation between the pancreatic hormones and the PG level this protocol includes five days. All days include a euglycemic-clamp, patients with T2DM (n=10) are clamped at their fasting PG as are healthy control subjects (n=10). During the clamp either GLP-1 alone; GLP-1 in combination with somatostatin, insulin and glucagon; or somatostatin, insulin and glucagon are infused and blood samples are drawn.

The design of the study makes it possible to isolate the effect of each hormone. Further the investigators will be able to enlighten the effect of GLP-1 on the increase in glucose turn-over it induces.

The essential part in this design will be hormone concentrations and the response parameter the amount of glucose (AUC) it takes to create the euglycemic-clamp.