The carbohydrate metabolism was analyzed in 70 patients with the complicated chronic pancreatitis before and after pylorus-preserving pancreatoduodenal resection (PPDR). Patients were aged 42±1,15 years, of them 64 were men and 6 - women. Bodymass index was 2,2±0,54kg/m2. Patients were divided in groups according to pre- and postoperative glucose metabolism disorders to define the diabetes morbidity by chronic pancreatitis and the influence of surgery on the first. According to the preoperative data, diabetes mellitus of mild severity had 9 of 70 operated patients, 18 patients had medium diabetes. After the operation only one patient demonstrated the aggravation of diabetes. However, the onset of diabetes mellitus was registered in 8 patients postoperatively. The increased glucose blood level in early postoperative period proved to have a high prognostic significance. Therefore, all patients of that category must be strongly recommended to be under the endocrinologist's observation after hospital discharge. That measure would provide a timely diagnose and treatment of the diabetes mellitus. All patients with chronic pancreatitis should be thoroughly investigated concerning glucose metabolism disorders before the operation.