Introduction: a significant improvement was shown in metabolic control at the early stages after BPD, which was associated with GLP-1 and was regardless of weight loss. Aim: to study the secretion of GLP-1, GIP, insulin and glucagon and their relationship to the parameters of the carbohydrate metabolism among patients with obesity and type 2 diabetes before and 3 months after BPD. Materials and Methods: the check-up involved 22 patients with obesity (BMI 50.1 [41.3; 53.8] kg/m²) and type 2 diabetes. Determined: glucose, HbA1c, insulin, glucagon, GLP-1, GIP. Results: after the surgery for weight loss of 15.8% was showed a reduction of fasting and postprandial glycemia, a reduction of AUCglucose, HbA1c, НОМА-IR and hyperinsulinemia. The secretion of GLP-1 with a peak at 30' (test with a standard breakfast) increased, AUCGLP-1 – to 1.8-fold, the basal secretion of GIP – almost 2-fold and AUCGIP – to 1.7-fold; decreased of a secretion of glucagon with a minimum at 60' and AUCglucagon. A negative correlation was revealed between GIP and glucagon, AUCglucose and AUCglucagon; a positive correlation was revealed between GLP-1 and insulin. The weight loss was accompanied by an inversely proportional increase of GLP-1. Conclusion: More than 90% of the surveyed patients achieved a satisfactory glycemic control as early as 3 months after BPD. The significant improvement of the parameters of the carbohydrate metabolism was associated with elevated levels of GLP-1 and this improvement does not depend of weight loss.