Inclusion Criteria:  Sleeve gastrectomy-operated > 12 months prior to inclusion Weight stable (+/- 3 kg during the last 3 months) Fasting glucose < 7,0 mmol/l / HbA1c < 48 mmol/mol pre- and postoperativ Signed written informed consent  Exclusion Criteria:  Pregnancy or breastfeeding. Haemoglobin < 6,5 mM.