Weight Change–Adjusted Effects of Gastric Bypass Surgery on Glucose Metabolism: 2- and 10-Year Results From the Swedish Obese Subjects (SOS) Study

Abstract

OBJECTIVEIt has been suggested that weight change-independent effects on fasting insulin and glucose levels are present after gastric bypass (GBP) but not after banding and vertical banded gastroplasty (VBG). We therefore evaluated weight change-adjusted effects of GBP, compared with restrictive surgical procedures, on long-term changes in fasting levels of glucose, insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) in the Swedish Obese Subjects (SOS) study. RESEARCH DESIGN AND METHODSParticipants who completed the 2-year (n = 1,762) and/or the 10-year (n = 1,216) follow-up were divided into three weight change classes (weight loss >30%, 20-30%, or £20%), and by surgical method (banding, VBG, or GBP). Glucose, insulin, and HOMA-IR changes were analyzed in relation to weight change over 2 and 10 years. Analyses were performed in the full cohort and also in subgroups based on baseline glucose status. RESULTSWithin weight change classes, reductions in glucose, insulin, and HOMA-IR were similar in the three surgery groups both at 2 and at 10 years. Reductions in glucose, insulin, and HOMA-IR increased with increasing weight loss, and changes were typically related to weight change within each surgery group. Moreover, the association between weight change and change in glucose, insulin, or HOMA-IR did not differ between the surgery groups at 2 and 10 years. When patients were subdivided also by baseline glucose status, similar relationships between weight changes and changes in glucose, insulin, and HOMA-IR were observed. CONCLUSIONSEven though weight loss-independent effects are important for short-term diabetes remission, our results suggest that degree of weight loss is more important for long-term reductions in fasting insulin and glucose than choice of bariatric surgery procedure.

Glucose Metabolism After Gastric Banding and Gastric Bypass in Individuals With Type 2 Diabetes: Weight Loss Effect

“…Larger (16.6% or 20%) weight loss after LAGB results in a decrease in fasting glucose levels and glucose AUC similar to that observed after 20% or 30% weight loss after RYGB, showing the importance of achieving a certain amount of weight loss over that of surgery type. This is in agreement with the study by Bradley et al (26) in individuals without diabetes and with recent data from the Swedish Obese Subjects study (39), which also suggest that weight change, rather than surgery type, is the best predictor of glucose control 2 and 10 years after bariatric surgery.…”

Risk of type 2 diabetes in patients with non-alcoholic fatty liver disease: Causal association or epiphenomenon?

“…Many more data are available on diabetes risk in relation to bariatric surgery-induced weight loss. In the Swedish Obese Subjects intervention study, surgery produced a systematic reduction of incident diabetes vs. obese matched controls [67]; the effect was directly associated with the amount of weight loss [68], not with baseline BMI [69]. In the same cohort of morbidly obese subjects undergoing surgery, weight loss was accompanied by a systematic reduction of serum liver enzymes at 2-year and 10-year follow-up, considered surrogate markers of steatosis, also proportional to the degree of weight loss [70].…”

Diabetes remission off medications is not a suitable endpoint for comparing bariatric/metabolic surgery with pharmacotherapy

“…Moreover, in larger studies involving patients with higher baseline BMI, such as the Swedish Obese Subjects (SOS) study, the degree of weight loss was significantly associated with glycaemic improvement; when stratified by weight, there were no differences between restrictive and malabsorptive (i.e. 'metabolic') surgical procedures [5,6]. Insofar as the present study was not powered to evaluate that question, as the authors correctly state, no conclusions different from what we already know from much bigger datasets can be reached.…”