Insulin action in subjects with type 2 diabetes following biliopancreatic diversion

Introduction: In obese subjects with type 2 diabetes (T2DM), bariatric surgery is followed in most cases by a stable metabolic improvement, with complete T2DM remission or a satisfactory T2DM control. On the contrary, just after bariatric surgery, a marked increase in insulin secretion develops, which persists for years after the operation. This study aimed to indirectly assess the insulin resistance and the insulin secretion before biliopancreatic diversion (BPD) and at five and ten years after the operation in a clinical sample of T2DM overweight and class 1 obesity patients. Methods: The study was carried out in a cohort of 100 class 1 obese or overweight T2DM patients seeking BPD for diabetes resolution. Before BPD, the patients underwent an accurate clinical assessment of the diabetic status, including fasting serum concentration of glucose (FBG), glycated haemoglobin (Hb1AC) and C-peptide. Following the operation, T2DM was considered as remitted when FBG was lower than 125 mg% at free diet and without antidiabetic drugs. Results: The follow-up rate was 78% at five years and 80% at ten years after BPD. At five years following BPD, the body weight (BW) and body mass index (BMI) mean values were markedly lower than that of the preoperative ones; at ten years, the findings remained substantially unchanged. At five years after the operation, T2DM was considered as remitted in 45 cases (p < 0.01 vs. preoperatively), whilst at ten years post BPD, a normal FBG was observed only in 21 patients (p < 0.01 vs. five-year data), thus indicating a late T2DM relapse in 24 patients. In patients who experienced T2DM remission at 10 years, BW and BMI postoperative changes were closely similar to those of their metabolically unsuccessful counterparts, whilst triglyceride/glucose index values were lower than preoperatively both at five and ten years after the operation (p <0.05 and p <0.02, respectively). Conclusions: This study indicates that in class 1 or overweight T2DM patients, BPD results in a stable long-term T2DM remission only in very few cases. Long-term investigations are mandatory after other types of metabolic/bariatric procedures, namely when the operation causes only a little or any stimulus to the insulin secretion.