To evaluate the effect of DPP-4 inhibition on glucagon counter-regulatory mechanisms at moderate hypoglycemia in metformin-treated subjects with T2DM

The glucagon response to mild (3.0 mmol/l) hypoglycemia with and without DPP-4 inhibition by sitagliptin will be evaluated in elderly subjects with metformin treated type 2 diabetes to explore whether DPP-4 inhibition affects glucagon counter-regulation.

Inclusion Criteria:

1. Written consent has been given.
2. Patients with metformin treated T2DM (metformin dose >0,5 g/day and stable during the preceding 3 months)
3. Age >65 years.
4. HbA1c 6.0-8.5% (43-67 mmol/mol; inclusive) at visit 1.
5. Ability to complete the study

Exclusion Criteria:

1. A history of any secondary forms of diabetes, e.g., Cushing's syndrome and acromegaly.
2. Type 2 diabetes, positive GAD antibodies
3. eGFR <60 ml/min
4. Acute infections which may affect blood glucose control within 4 weeks prior to visit 1
5. Any history of recent (<2 weeks) recurrent or severe hypoglycemic episodes.
6. Liver disease such as cirrhosis or chronic active hepatitis
7. History of coronary heart disease or heart failure class III or IV
8. Donation of one unit (500 ml) or more of blood, significant blood loss equaling to at least one unit of blood within the past 2 weeks or a blood transfusion within the past 8 weeks.
9. Treatment with growth hormone of chronic oral or parenteral corticosteroid treatment (> 7 consecutive days of treatment) within 8 weeks prior to visit 1.
10. Use of other investigational drugs at visit 1 or within 30 days of visit 1, unsuitable for the study

4 weeks