This study aimed to compare the efficacy of laparoscopic sleeve gastrectomy (SG) with that of laparoscopic gastric bypass (GBP) and laparoscopic adjustable gastric banding (AGB) for glucose homeostasis in morbidly obese subjects with type 2 diabetes mellitus (T2DM) at a 3-year follow-up assessment and to elucidate the role of weight loss in the T2DM resolution after SG.

For this study, 60 morbidly obese T2DM patients (44 females and 16 males) who underwent AGB (24 patients), GBP (16 patients), or SG (20 patients) between 1996 and 2008 were retrospectively analyzed. Age, sex, body mass index (BMI), estimated weight loss (EWL), fasting glycemia, HbA1c, euglycemic hyperinsulinemic clamp, discontinuation of diabetes treatment, and time until interruption of therapy were evaluated.

In the study, 54 patients received oral hypoglycemic agents for at least 12 months before surgery, and 6 patients received insulin. The mean follow-up period was 36 months. The resolution rate was 60.8% for the AGB patients, 81.2% for the GBP patients, and 80.9% for the SG patients. The postoperative time until interruption of therapy was 12.6 months for the AGB patients, 3.2 months for the GBP patients, and 3.3 months for the SG patients. The hyperinsulinemic euglycemic clamp test was performed 12 months after surgery for the cured patients. Insulin resistance was restored to normal values in all the patients. The greatest improvement from preoperative values occurred in the SG group. For the not-cured GBP and SG patients, an improvement of 120 mg/dl in fasting plasma glucose was observed 3 months after the surgery, suggesting an enhancement in insulin sensitivity, which determines better medical control. The resolution rate remained constant at the 36-month follow-up evaluation in both the GBP and SG groups.

All three bariatric procedures are effective in treating diabetes, with a 3-year follow-up evaluation showing an effect that lasts. The AGB procedure was the least effective. The antidiabetic effect was similarly precocious after GBP and SG compared with AGB. This difference may indicate that a hormonal mechanism may be involved, independent of weight loss.