Does Gastric Bypass Improve Glycemic Control Beyond the Effect of Weight Loss?

Some evidence suggests that in obese patients with type 2 diabetes, interruption of intestinal continuity after gastric bypass surgery might confer favorable effects on glucose metabolism — independent of weight loss. To examine this premise, researchers in St. Louis compared 11 patients who had undergone Roux-en-Y gastric bypass surgery and 11 patients who lost comparable weight through strict low-calorie dieting; all patients had long-standing type 2 diabetes.

Comprehensive testing of insulin sensitivity and β-cell function was conducted in a university clinical research unit prior to surgery or dieting (when mean body-mass index [BMI] was 43 kg/m² in both groups) and again after surgery or dieting (when mean BMI was 35 kg/m² in both group…