Improved glucose metabolism after gastric bypass: evolution of the paradigm

• Background: Glucose metabolism is improved in patients with type 2 diabetes after Roux-en-Y gastric bypass (RYGB). Objectives: To quantify the relative contribution of calorie restriction, rerouting of nutrients, and adipose tissue reduction. Methods: Fifteen diabetic patients, (47 +/- 9 yr, body mass index 41.3 +/- 4.2 kg/m(2)) were randomized to a 2-week very low-calorie diet (VLCD) regimen or normal diet before RYGB. A euglycemic-hyperinsulinemic clamp, indirect calorimetry, and a standard meal test were performed prediet, postdiet (preoperatively), and 2 weeks and 12 months postoperatively. The primary outcome was whole-body insulin sensitivity (M) measured with the clamp 2 weeks postoperatively. Results: In the VLCD group, after 2 weeks of calorie restriction, M improved (2.9 +/- 1.3 to 4.2 +/- 1.1 mg/kg/min, P = .005) with no further change at 2 weeks postoperatively. In the normal diet group 2 weeks postoperatively, M was similar to the VLCD group (4.7 +/- 1.7 versus 4.2 +/- 1.1, P = .61). One year postoperatively, M improved further in both groups. The improvement in insulin-stimulated glucose uptake after VLCD and RYGB was entirely accounted for by nonoxidative glucose disposal (NOGD), whereas weight loss at 1 year postoperatively was associated with an increase in NOGD and glucose oxidation. Postprandial glucose improved after VLCD (P < .05) and even more 2 weeks after RYGB (P < .05) with no further change after 1 year. Conclusion: Improved whole-body insulin sensitivity and postprandial glucose response occur early after RYGB. Low calorie intake and rerouting of nutrients contribute through distinct mechanisms. Weight loss contributes by increasing whole-body insulin sensitivity, including glucose oxidation and NOGD. These data suggest that the combination of different mechanisms is what makes RYGB an effective intervention for type 2 diabetes. (C) 2016 American Society for Metabolic and Bariatric Surgery. All rights reserved.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Gastroenterologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Gastroenterology and Hepatology (hsv//eng)

Nyckelord

Diabetes mellitus type 2

Obesity

Insulin resistance

Glucose clamp technique

Bariatric surgery

Gastric bypass

Randomized controlled trial

beta-cell function

substrate oxidation rates

low-calorie diet

weight-loss

insulin sensitivity

bariatric surgery

medical therapy

obese-patients

resistance

management

Surgery

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