Improvement in Insulin Sensitivity and Β-Cell Function Following Ileal Interposition with Sleeve Gastrectomy in Type 2 Diabetic Patients: Potential Mechanisms

Introduction Bariatric surgery in morbidly obese type 2 diabetic (T2DM) patients is associated with high rates of diabetes remission. We investigated the mechanisms of the anti-diabetic effect of the laparoscopic ileal interposition with sleeve gastrectomy (LII-SG) in normal weight (NW), overweight (OW) and obese (OB) T2DM patients. Methods Ninety-four patients (aged 54±8 years) with long-standing (median 10 years), treated diabetes (median HbA1c= 8.6%), who were NW (15), OW (64) or OB (15) based on BMI, underwent LII-SG. Insulin sensitivity and parameters of scell function were measured from an Oral Glycaemic Tolerance Test pre- and post-operatively. Results At a median of 13.4 months post-operatively, weight loss averaged 9.4±1.3, 16.8±0.8 and 23.2±1.7 kg in NW, OW and OB subjects, respectively (p<0.0001). Insulin sensitivity was fully restored (395 [108] vs 208 [99] ml min �1 m �2 ), fasting insulin secretion rate decreased (68 [52] vs 146 [120] pmol min �1 m �2 ) and total insulin output increased (52 [26] vs 39 [28] nmol m �2 , all p≤0.001). s-cell glucose sensitivity doubled (37 [33] vs 18 [24] mol min �1 m �2 mM �1 , p<0.0001). The only parameter predicting remission of diabetes was a lower baseline insulin sensitivity (p=0.005). Conclusions LII-SG induced changes on T2DM by mechanisms in part distinct from weight loss, principally involving restoration of insulin sensitivity and improvement of s-cell function.