The Impact of Bariatric Surgery on Obesity related Metabolic Traits with Specific Emphasis on Glucose, Insulin and Proinsulin

University dissertation from Uppsala : Acta Universitatis Upsaliensis

Abstract: Hyperproinsulinemia is associated with type 2 diabetes (T2DM) and obesity and is a predictor for future coronary heart disease. This thesis examines the effect of bariatric surgery on glucometabolic status including insulin and proinsulin responses after meal. Further we explored longitudinally the effects of bariatric surgery on glucose, insulin and proinsulin secretion as well as lipids, liver enzymes and magnesium concentrations.We explored by a standardised meal test the postprandial dynamics of proinsulin and insulin and effects on glucose and lipids in patients treated with gastric bypass (RYGBP) surgery and in patients treated with bileopancreatic diversion with duodenal switch surgery (BPD-DS). Comparisons were made to morbidly obese patients and normal weight controls (NW). RYGBP surgery markedly lowers fasting and postprandial proinsulin concentrations although BMI was higher compared to NW-controls. BPD-DS surgery induces a large weight loss and normalises postprandial responses of glucose, proinsulin and insulin and markedly lowers triglycerides.We evaluated non-diabetic morbidly obese patients who underwent bariatric surgery followed-up for up to four years after surgery. Long-term follow-up showed that RYGBP surgery is not only characterized by markedly and sustained lowered BMI but also lowered concentrations of proinsulin, insulin, ALT and increased HDL-C possibly via reduced hepatic insulin resistance.We also examined how magnesium status is affected by bariatric surgery as magnesium has been shown to be inversely related to glucose and to insulin resistance. The serum magnesium concentrations increased by 6% after RYGBP and 10% after BPD-DS.In summary, RYGBP and BPD-DS surgery results in marked weight loss, alterations in insulin and proinsulin dynamics, lowered fasting and postprandial proinsulin concentrations and improved glucometabolic and magnesium status.