Besides causing weight loss Roux-en-Y gastric bypass (RYGB) has profound effect on glucose metabolism leading to remission of type 2 diabetes early after surgery. However the mechanisms for this improvement remain uncertain. The aim of this study is to investigate the changes in insulin sensitivity and beta-cell function 1 week and 3 months following RYGB using oral and intravenous test.
Investigators plan to study 24 obese patients already enrolled for Roux-en-y gastric bypass surgery (RYGB). 8 with type 2 diabetes (DM2), 8 with impaired glucose tolerance (IGT) and 8 with normal glucose tolerance (NGT) before, within the first week and 3 month after RYGB using a liquid mixed meal test (MMT) and an insulin modified frequently sampled intravenous glucose tolerance test (IM-FSIGT). Furthermore, an oral glucose tolerance test (OGTT) will be performed before and after 3 months. Blood will be sampled in fasting and during the tests measuring plasma glucose, insulin and C-peptid (OGTT, MMT and IM-FSIGT) and GLP-1, glucagon, GIP and GLP-2 (MMT). Beta-cell function will be assessed from the MMT (insulinogenic index - IGI), OGTT (IGI) and the IM-FSIGT (Acute insulin response, AIR) in order to examine whether changes in beta-cell function after RYGB depend on an oral stimulus. Insulin sensitivity will be assessed in fasting (HOMA-IR), during the IM-FSIGT (minimal model: Si) and from MMT/OGTT (Matsuda index). Insulin clearance/hepatic extraction of insulin will be assessed in fasting and during the intravenous and oral test.
Study Type
OBSERVATIONAL
Enrollment
24
Hvidovre University Hospital
Copenhagen, Hvidovre, Denmark
RECRUITINGChange in beta-cell function after RYGB.
Beta-cell function will be assessed with both intravenous tests (acute insulin response to glucose - AIRg) and oral tests (insulinogenic index - IGI).
Time frame: 1 week and 3 months.
Change in insulin sensitivity after RYGB.
Insulin sensitivity will be assessed in fasting and by intravenous tests (sensitivity index - Si) and oral tests (Matsuda index).
Time frame: 1 week and 3 months.
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