Diabetes Remission and Insulin Secretion after Gastric Bypass in Patients with Body Mass Index < 35 Kg/M2

Most morbidly obese patients who undergo gastric bypass experience rapid remission of type 2 diabetes mellitus T2DM but the response in non- morbidly obese patients is not clear . This trial prospectively assessed the effect of diabetes remission, glucose metabolism, and the serial changes of insulin secretion after gastric bypass in inadequately controlled T2DM patients with a BMI of 23-35 kg/m2. A total of 62 consecutive patients with T2DM and a BMI of 23-35 kg/m 2 underwent gastric bypass. Data were prospectively collected before surgery and 1, 4, 12, 26 , and 52 weeks and 2 years after surgery. Insulin secretion was measured by insulinogenic index and area under the curve AUC during a standard oral glucose tolerance test OGTT. Remission of type 2 diabetes was defined as fasting glucose level < 110 mg/dl and HbA1c < 6.0% without any glycemic therapy. Of the 62 patients, 24 were men and 38 were women age 43.1 +/- 10 .8 years. Their preoperative characteristics were as follows: BMI 30.1 +/- 3.3 kg/m2, waist circumference 99.6 +/- 9.6 cm, C-peptide 3.1 +/- 1.4 ng/ ml, and duration of T2DM 5.4 +/- 5 .1 years. The mean BMI decreased postoperatively to 22.6 +/- 2.3 kg/m2 in 1 year and 23.0 +/- 2.7 kg/m2 in 2 years. The mean HbA1c decreased from 9.7 +/- 1.9% to 5.8 +/- 0.5% in 1 year and 5.9 +/- 0.5% in 2 years. Complete remission of T2DM was achieved in 57% in 1 year and 55% in 2 years after surgery. Before surgery, the OGTT test showed a blunted insulin secretion pattern with an insulinogenic index of 0.1 +/- 0.2 and AUC of 2,324 +/- 1,015 mu IU min/ml. In 1 week after surgery, the insulinogenic index increased to 0.16 and AUC decreased to 1,366 mu IU min/ml along with a rapid drop of insulin resistance. The insulinogenic index and AUC gradually increased to 0.27 and 3,220, respectively, 1 year after surgery and remained stable up to 2 years with a very low insulin resistance. Laparoscopic gastric bypass facilitates immediate improvement in the glucose metabolism of inadequately controlled non-severe obese T2DM patients, and the benefit is sustained up to 2 years after surgery. The benefit is regulated by the decrease in insulin resistance, increase in early insulin response, and total insulin secretion to glucose load