Effects of Marked Weight Loss Induced by Gastric Bypass Surgery or Low-Calorie Diet Alone on Postprandial Glucose Disposal in Type 2 Diabetes

We used a dual (intravenous and oral) glucose tracer pro-tocol to evaluate rates of glucose appearance in the circu-lation, insulin-mediated glucose disposal (IMGD), and noninsulin-mediated glucose disposal (NIMGD) for 4 h after consumption of a mixed meal in people with obesity and type 2 diabetes before and after marked (20%) weight loss, induced by behavioral diet therapy (BDT, n = 11) or Roux-en-Y gastric bypass (RYGB) surgery (n = 9). Total postprandial glucose appearance rate was lower after compared with before weight loss in both the BDT and RYGB groups because of a decrease in endogenous glucose production, without a difference between groups. However, the decreases in total and incremental post-prandial plasma glucose concentration areas under the curve were greater in the BDT group than the RYGB group because IMGD doubled in the BDT group but did not change in the RYGB group. These results demonstrate that the improvement in postprandial glycemia is greater after marked, matched weight loss induced by BDT compared with RYGB in people with obesity and type 2 diabe-tes, because of increased IMGD after BDT but not RYGB. Nonetheless, these findings do not diminish the potent therapeutic effect of RYGB surgery on glycemic control and even achieving remission of type 2 diabetes.