Hepatic and peripheral insulin sensitivity do not improve 2 weeks after bariatric surgery

Abstract

Objective: Bariatric surgery has rapid metabolic effects on glucose metabolism before the occurrence of clinically significant weight loss. This suggests an acute effect of the surgery itself, e.g., resulting from bypassing the nutrient flow from the proximal gastrointestinal tract. Rapid effects of Roux-en-Y gastric bypass surgery (RYGB) on glucose metabolism were defined. Design and Methods: Glucose metabolism and total triglyceride hydrolysis in the basal state and during a hyperinsulinemic euglycemic clamp using stable isotopes 2 weeks were studied before and after RYGB. Results: Eighteen pre-menopausal women scheduled for RYGB were included. 2 weeks after RYGB median weight loss was 7.8 kg. Basal insulin and glucose levels decreased after surgery. Endogenous glucose production (EGP) was lower after surgery. In addition, insulin levels were lower during the clamp after surgery, suggesting enhanced clearance. Hepatic and peripheral insulin sensitivity did not change. Free fatty acid (FFA) levels increased after surgery both in the basal state and during the first step of the clamp. Total triglyceride hydrolysis did not change in the basal state and tended to be higher during hyperinsulinemia. Conclusions: Within 2 weeks, RYGB reduces basal EGP as well as insulin and glucose levels without an acute beneficial effect on hepatic or peripheral insulin sensitivity. The latter may be explained by higher rates of lipolysis and exposure to FFA induced by the hypocaloric state.

Insulin resistance in obesity can be reliably identified from fasting plasma insulin

“…[10][11][12][13][14][15][16][17] Consecutive adults who underwent a two-step EHC (insulin infusion 20 and 60 mU m − 2 min −1 ) were included in the analysis when the following data could be retrieved: sex, age, body mass index (BMI), diabetes status, and either basal EGP, suppression of EGP or glucose rate of disappearance (R d ). Additionally, we obtained data on body composition using bioimpedance analysis, 12 resting energy expenditure (REE) using indirect calorimetry, 12 fasting plasma glucose (FPG), insulin (FPI) and lipids as well as plasma glucoregulatory hormones during the clamp for most, but not all subjects. Self-reported body weight was stable (that is, o5% weight change) for at least 3 months before examinations.…”

“…[10][11][12][13] After an overnight fast, catheters were inserted into peripheral veins of both arms for infusion of the glucose tracer, glucose and insulin, and sampling of arterialized blood using a heated-hand box (60°C), respectively. We used [6,6-2 H 2 ]glucose (499% enriched; Cambridge Isotopes, Andover, MA, USA) as tracer.…”

“…Insulin, cortisol and glucagon were determined as previously described. 12 Plasma lipids were determined by automated enzymatic colometric methods as previously described. 15 Plasma enrichment of [6,6-2 H 2 ]glucose (tracer-to-tracee ratio) was determined by gas chromatography-mass spectrometry as previously described.…”

The vitamin D metabolites 25(OH)D and 1,25(OH)2D are not related to either glucose metabolism or insulin action in obese women

“…All had participated in different metabolic studies, the results of which have been partially described elsewhere [18]. Subjects were eligible to participate in the present study if they were aged > 18 years, met the criteria for bariatric surgery according to national guidelines [19], were scheduled to undergo Roux-en-Y gastric bypass surgery and had stable weight (< 5% weight change) for at least 3 months prior to examination.…”

“…Levels of glucoregulatory hormones and FFA were determined as previously described [18]. Plasma enrichment of [6,6-2 H 2 ]glucose (tracer-to-tracee ratio) was determined by gas chromatography-mass spectroscopy as previously described [22].…”