GLP-1 and Adiponectin: Effect of Weight Loss After Dietary Restriction and Gastric Bypass in Morbidly Obese Patients with Normal and Abnormal Glucose Metabolism

Background  It has been proposed that there is improvement in glucose and insulin metabolism after weight loss in patients who underwent diet restriction and bariatric surgery. Methods  Eleven normal glucose tolerant (NGT) morbidly obese patients [body mass index (BMI), 46.1 ± 2.27 g/m²] and eight abnormal glucose metabolism (AGM) obese patients (BMI, 51.20 kg/m²) were submitted to diet-restriction and bariatric surgery. Prospective study on weight loss changes, over the glucose, insulin metabolism, glucagon-like peptide-1 (GLP-1), and adiponectin levels were evaluated by oral glucose tolerance test during three periods: T1 (first evaluation), T2 (pre-surgery), and T3 (9 months after surgery). Results  Insulin levels improved after surgery. T1 was 131.1 ± 17.60 pmol/l in the NGT group and 197.57 ± 57.94 pmol/l in the AGM group, and T3 was 72.48 ± 3.67 pmol/l in the NGT group and 61.2 ± 9.33 pmol/l in the AGM group. The major reduction was at the first hour of the glucose load as well as fasting levels. At 9 months after surgery (T3), GLP-1 levels at 30 and 60 min had significantly increased in both groups. It was observed that the AGM group had higher levels of GLP-1 at 30 min (34.06 ± 6.18 pmol/l) when compared to the NGT group (22.69 ± 4.04 pmol/l). Homeostasis model assessment of insulin resistance from the NGT and AGM groups had a significant reduction at periods T3 in relation to T1 and T2. Adiponectin levels had increased concentration in both groups before and after surgical weight loss. However, it did not have any statistical difference between periods T1 vs. T2. Conclusions  Weight loss by surgery leads to improvement in the metabolism of carbohydrates in relation to sensitivity to the insulin, contributing to the reduction of type 2 diabetes incidence. This improvement also was expressed by the improvement of the levels of adiponectin and GLP-1.