In order to evaluate the difference in beta cell mass in patients with and without complete resolution of type 2 diabetes mellitus (T2DM) after Roux en Y gastric bypass (RYGB) investigators aim to compare quantitative PET imaging of the pancreas between these patient groups. These highly relevant data will provide investigators with more information on the possible role of beta cell mass in the mechanisms behind resolution of T2DM after bariatric surgery. This would be of great interest for the assessment of RYGB as an alternative therapy in patients with T2DM with a BMI \<35, who currently do not meet the international guidelines for bariatric surgery.