Laparoscopic sleeve gastrectomy for diabetes treatment in nonmorbidly obese patients: efficacy and change of insulin secretion

Abstract

Background: Sleeve gastrectomy is a new bariatric surgery, and many reports have showed that patients who have undergone sleeve gastrectomy have experienced rapid resolution of type 2 diabetes. The mechanisms accounting for the beneficial effects of sleeve gastrectomy on glucose homeostasis are not well understood and remain speculative. This trial assessed prospectively the effect of sleeve gastrectomy on type 2 diabetes and the serial changes of insulin secretion to oral glucose loads.

Methods: Prospective study on the response of insulin secretion to oral glucose loads in 20 severe diabetic patients (body mass index [BMI] >25 and <35, HbA1C >7.5%) before and at 1, 4, 12, 26, and 52 weeks after sleeve gastrectomy. The 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 <126 mg/dL and HbA1C <6.5% without any glycemic therapy.

Results: Of the 20 patients enrolled, the mean age was 46.3 + or - 8.0 years, mean BMI was 31.0 + or - 2.9 kg/m(2), and mean HbA1C was 10.1 + or - 2.2. The mean BMI and excess body weight loss at 1, 4, 12, 26, and 52 weeks after operation were 28.9 (22.1%), 27.4 (43.0%), 25.7 (55.1%), 24.9 (71.9%), and 24.6 (69.1%), respectively. The mean HbA1C at 1, 4, 12, 26, and 52 weeks after operation were 9.2, 8.4, 7.7, 7.3, and 7.1, respectively. Resolution of type 2 diabetes was achieved in 2 (20%) patients at 4 weeks, 6 (30%) at 12 weeks, 8 (40%) at 26 weeks, and 10 (50%) at 52 weeks after sleeve gastrectomy. Before operation, the mean fasting plasma glucose and insulin levels were 240.1 + 80.9 mg/dL and 16.8 + or - 15.4 uIU/mL, respectively. The OGTT test showed a blunted insulin secretion pattern with an AUC of 3,135 uIU x min/mL. At 1 week after operation, the fasting plasma glucose and insulin levels significantly decreased to 158 + or - 52 mg/dL and 5.6 + or - 3.2 uIU/mL, respectively. The AUC decreased to 2,988.7 uIU x min/mL. The AUC at 4, 12, 26, and 52 weeks after operation was 2,211, 1,584, 3,621, and 3,351 uIU x min/mL, respectively. The diabetes resolution rates for those with pre-operative C-peptide <3, 3-6, and >6 ng/mL were 1/7 (14.3%), 7/11 (63.6%), and 2/2 (100%), respectively (P < .05).

Conclusion: Laparosopic gastric sleeve gastrectomy resulted in remission of poorly controlled nonmorbidly obese T2DM patients up to 50% at 1 year after operation. The effect is related more to the decreasing of insulin resistance because of calorie restriction and weight loss rather than to the increasing of insulin secretion. C-peptide >3 ng/mL is the most important predictor for a successful treatment.