Patients suffering from schizophrenia have a high risk to become obese and develop diabetes. Risk of obesity is particularly high with some newer schizophrenia drugs, such as clozapine or olanzapine. These drugs are called atypical drugs and exert their action in part by occupying receptors for serotonin, particularly the 5HT2A receptor subtype. This receptor may also interfere with glucose metabolism and insulin action. The purpose of this study is to compare an atypical antipsychotic drugs, olanzapine, which acts by occupying the 5HT2A receptor, to another antipsychotic drug, amisulpride, which mainly acts through the dopamine pathway. Healthy volunteers are recruited and asked to take a single dose of each drug and of placebo on separate days. Then, a combined glucose clamp study will be performed in order to test the effects of these drugs on insulin sensitivity and insulin secretion.

10 male healthy volunteers are recruited. After informed consent, they are admitted to the study ward at 10:00 p.m. prior to the study day and kept fasting until the next morning. At 8:00 a.m. they receive their study medication (olanzapine, amisulpride or placebo). Subsequently, measurements of insulin sensitivity and insulin secretion are performed by euglycemic hyperinsulinemic clamp technique followed by hyperglycemic clamp.

Inclusion Criteria:

• healthy male volunteers
• written informed consent

Exclusion Criteria:

• BMI > 30 kg/m²
• Diabetes mellitus
• Hypertension
• Treatment with drugs interfering with lipid or glucose metabolism (e.g. statins, oral antidiabetic drugs, glucocorticoids)
• History of seizures