The purpose of this study is to evaluate whether the reduced incretin effect and the paradoxical glucagon responses during oral glucose ingestion and isoglycaemic iv glucose infusion observed in patients with type 2 diabetes are causes (non-inducible in lean healthy subjects without family history of diabetes) or consequences (inducible) of the diabetic state.

The incretin effect is severely reduced in patients with type 2 diabetes. This pathophysiological trait is accompanied by an almost abolished insulinotropic effect of the incretin hormone glucose-dependent insulinotropic polypeptide (GIP) and a reduced insulinotropic potency of the other incretin hormone glucagon-like peptide-1 (GLP-1). Furthermore, recent studies suggest that hypersecretion of glucagon during oral glucose ingestion, as opposed to a normal suppression of glucagon during isoglycaemic intravenous (iv) administered glucose, further attenuates the incretin effect in patients with type 2 diabetes.

However, it remains unclear whether the severely reduced incretin effect and its accompanying pathophysiological traits characterizing patients with type 2 diabetes can be induced temporarily in healthy subjects by a short period of glucose homeostatic dysregulation.

In this study the incretin effect will be measured using 50-g oral glucose tolerance test and isoglycaemic iv glucose infusion and meal test in 10 healthy Caucasian subjects without family history of diabetes before and after dysregulation of glucose homeostasis using high calorie diet, physical inactivity and administration of adrenocortical steroids

Inclusion Criteria:

• Caucasians without Type 2 or Type 1 Diabetes
• Normal OGTT (75 g of glucose) according to WHO criteria
• Normal hemoglobin
• Normal blood pressure

Exclusion Criteria:

• Liver disease
• Kidney disease
• Relatives (parents/siblings) with type 2 diabetes
• Pregnancy
• Contra-indications to treatment with adrenocortical steroids