GASTRIC BYPASS SURGERY HAS GREATER EFFECT THAN CALORIE RESTRICTION ON INCRETIN RELEASE AND INSULIN SECRETION ALREADY ON POSTOP. DAY 1

Summary, in English

Background: Gastric bypass surgery (GBP) provokes rapid improvement of type 2 diabetes (T2D) prior to significant weight loss. This
has been attributed to altered secretion of the two incretin hormones glucagon-like peptide 1 (GLP-1) and glucose-dependent
insulinotropic polypeptide (GIP). Here we studied the effects of very low calorie diet (VLCD) vs. the immediate effects of GBP on
glycaemia and incretin release.
Methods: Eight T2D obese women and 8 obese controls (C) underwent mixed meal tests (MMT) 4 w before (MMT-4w), 1 day before
(MMT-1d), 1 day after (MMT+1d) and six weeks after (MMT+6w) gastric bypass. MMT-4w was performed before VLCD and MMT+1d
constituted the first postoperative meal. Glucose, insulin and incretins were analyzed. Gastric bypass surgery was standardized to a 50
cm biliary limb and 150 cm alimentary limb and a 5 cm gastric pouch.
OBES SURG (2015) 25 (Suppl 1):S1–S364 S85
Results: Despite similar glucose levels, the insulin response was markedly increased at MMT+1d, compared to MMT-4w and MMT-1d
(2.4- and 2.8-fold). At MMT+6w a more rapid rise was evident. GLP-1 levels were similar in all MMTs except MMT+6w where an
increased response was seen; this was stronger in T2D vs. C. The GIP-response was higher at MMT+1d, compared to MMT-4w and
MMT-1d (1.6- and 1.4-fold). The increased GIP-response was attenuated in C at MMT+6w, but still evident in T2D.
Conclusions: VLCD has minor impact on the parameters analyzed; rather GBP per se elicits an immediate stimulatory effect on insulin
and GIP levels in response to an MMT as first meal on day 1 after surgery.