The Role of Bariatric Surgery in Patients with Obesity and Type 1 Diabetes Mellitus

Introduction: Little is known of the effects of bariatric surgery on type 1 diabetes mellitus (T1DM). Systemic reviews of various case reports and a number of original articles in the literature show mixed effects of surgery on HbA1c and daily insulin requirements in patients with T1DM. The aim of this study is to assess the impact of bariatric surgery on obesity, obesity-related conditions, and glycemic control in patients with T1DM. Methods: We retrospectively reviewed 13 patients with obesity and insulin-dependent diabetes mellitus (T1DM) at four different institutions between 2012 and 2016. The diagnosis was confirmed by the presence of autoantibodies known to be associated with T1DM (GAD 65, insulin antibodies) and/or the absence of C-peptide. The primary end points of the study were glycemic control, as measured by HbA1c and the daily insulin requirement. Secondary end points included mean percentage weight loss and resolution rate of comorbidities. Results: Of the 13 patients studied 8 (61.5%) were female with a mean age of 39.6 +/- 10.1 (30-56) years, and 5 (38.5%) were male with a mean age of 35.6 +/- 13.2 (19-52) years. All subjects had a mean preoperative BMI of 45.8 +/- 6.8 (35.4-58.6) kg/m(2), mean weight of 125.8 +/- 20.7 (93-161) kg, and a mean preoperative HbA1c of 8.3 +/- 1.5 (6.6-12.2)%. Mean daily insulin requirement (the sum of the basal and premeal bolus doses), among all patients, was 120.6 +/- 58.9 (50-220) units. Ten (76.9%) patients had dyslipidemia, eight (61.5%) patients had hypertension, and five (38.5%) had obstructive sleep apnea. Ten (76.9%) patients underwent a laparoscopic sleeve gastrectomy, two (15.4%) had laparoscopic Roux-en-Y gastric bypasses, and one (7.7%) patient underwent a single anastomosis bypass. There was a significant difference in mean weight loss from baseline to the weight at every interval follow-up (p-value <0.05). A significant difference in mean decrease in HbA1c was found from baseline to 6- and 12-month follow-up (p-value <0.05). There was both a clinically and statistically significant difference in mean daily insulin requirement, between the preoperative and follow-up doses. Conclusions: This study demonstrates that bariatric surgery can be an effective adjunct in the management of T1DM, in association with obesity. The results of our investigation revealed sustained improvement in weight, significant short-term improvement in HbA1c, and significant reduction in daily insulin requirements. Larger prospective randomized controlled studies will need to be done to confirm these findings and to evaluate if these improvements are sustained.