The impact of bariatric surgery on insulin-treated type 2 diabetes patients

Introduction Bariatric surgery has been shown to lead to significant improvement in glucose homeostasis, resulting in greater rates of type 2 diabetes mellitus (T2DM) remission. While there is substantial evidence of the benefits of bariatric/metabolic surgery in obese diabetic patients on oral therapy (O-T2D), more evidence is necessary in the case of insulin-treated type 2 diabetes (I-T2D) patients and the selection of surgical procedure. Methods Analysis of the Ontario Bariatric Registry data was performed, comparing outcomes of Roux-en-Y-gastric bypass (RYGB) and sleeve gastrectomy (SG) on insulin-treated versus non-insulin-treated T2DM patients. We compared weight loss, medication use and remission rates during a 3-year follow up. Results A total of 3668 diabetic Bariatric Registry patients underwent surgery from Jan 2010 to Feb 2017, across 7 Bariatric Centers of Excellence in Ontario. Of these 2872 were O-T2D and 1187 were I-T2D. Weight loss was similar between the two groups at 3 years; with mean %WL of 30.1% for the insulin group vs. 28.3% non-insulin (p = 0.0673). At 3 years, 11.3% of the non-insulin and 59.6% of the insulin-dependent group were using anti-diabetic medication (p < 0.0001). Among insulin-dependent patients, RYGB showed greater reduction in insulin use with 26.5 and 40% compared to SG at 3 years. O-T2D patients experienced more complete diabetes remission, with 66.5 vs. 18.5% (p < 0.0001) at 3 years. Complete remission for I-T2D patients was higher in the RYGB group than SG (p < 0.0001) at years 1 and 2 (8.5 vs. 5.4% and 24.4 vs. 21.1%). The same trend was found regardless of insulin use; complete remission higher for RYGB at 1 and 2 years [50.7 vs. 39.8% (p < 0.0001), and 54.6 vs. 49.1% (p < 0.0001)]. Conclusion While both RYGB and SG procedures provide effective treatment for I-T2D patients in terms of weight loss and diabetes, incidence of complete remission for insulin-dependent patients is higher with RYGB in earlier years.