study hypothesis to examine the acute effects on glycaemia and islet hormone secretion of increased levels of endogenous GLP-1 and GIP on islet cell function in men with type 2 diabetes. To this purpose, a standardized mixed meal test will be ingested with or without concomitant administration of sitagliptin (100mg).

In men subjects with type 2 diabetes treated with diet and exercise with or without metformin treatment as an antidiabetic agent, a standardized mixed meal test will be served with or without administration of sitagliptin (100mg).

Inclusion Criteria:

• Caucasian men with type 2 diabetes diagnosed according to ICD10
• Ongoing treatment with life style adjustment or life style adjustment together with metformin as oral antidiabetic. Metformin therapy should not exceed 2 grams daily
• Age 20-75 years
• HbA1c ≤80 mmol/mol
• BMI: 20-40 kg/m2

Exclusion Criteria:

• Liver disease or ALAT three times above upper reference range
• Diabetic nephropathy (GFR < 50 mL/min/1.73 m2 or albuminuria)
• Proliferative diabetic retinopathy
• Treatment with any glucose-lowering medication except metformin
• Previous myocardial infarction, coronary heart disease or insatiable angina pectoris in the last 6 months.
• Previous surgery on the gastrointestinal tract
• Larger surgical intervention during the last 12 weeks
• Treatment with oral steroids or thiazide diuretics
• Treatment with digoxin
• Smokers
• Participation in another study the last 4 weeks
• Paracetamol intolerance