The prevalence of obesity in type I diabetes mellitus has been increasing over the past decades. Multiple studies have demonstrated suboptimal outcomes with dietary control and medical management for obesity and diabetes mellitus type I. This study's objective was to evaluate insulin and diabetic medication requirements in patients with type I diabetes mellitus two years after bariatric surgery.


This was a retrospective chart review study from 2002-2019 at Geisinger health system. Of 4549 total bariatric surgeries, 38 bariatric surgery patients were confirmed to have type I diabetes mellitus. Type I diabetes mellitus was confirmed by chart review and/or presence of c-peptide <5 ng/mL.


The patient cohort had a mean age of 41 years, with 87% being female. The mean BMI was 43.0, with a mean HbA1c of 8.4% before surgery. During follow-up the insulin requirements improved from 114 units preoperatively to 60 units at 1 year postoperatively (SD= 54.5, p= 0.0018) and 60 units at 2-years postoperatively (SD= 60.3, p= 0.0033). Though not significant, the number of patients on more than one diabetic medication decreased from 66% preoperatively to 53% 1-year postoperatively (p=0.343) and 52% at 2-years (p=0.149).


This study demonstrated significant improvement in the insulin and the total number of diabetic medication requirements after bariatric surgery, suggesting that bariatric surgery may be a viable treatment within patients that have type I diabetes mellitus.