Effect of Roux-en-Y gastric bypass on pharmacologic dependence in obese patients with type 2 diabetes

Background: More than half the diabetes-related health care costs in Canada relate to drug costs. We aimed to determine the effect of Roux-en-Y gastric bypass (RYGB) on the use of insulin and orally administered hypoglycemic medications in patients with diabetes. We also looked to determine overall cost savings with the procedure. Methods: We reviewed the bariatric clinic records of all patients with a confirmed diagnosis of type 2 diabetes mellitus who underwent RYGB between 2010/11 and 2014/15. Percentage estimated weight loss was recorded at 1 year, along with reductions in glycated hemoglobin (HbA1c) level and use of oral hypoglycemic therapy and insulin. We estimated medication costs using Manitoba-specific pricing data. Results: Fifty-two patients with at least 12 months of complete follow-up data were identified. The mean percentage estimated weight loss was 50.2%. The mean HbA1c level decreased from 7.6% to 6.0%, the mean number of orally administered hypoglycemics declined from 1.6 to 0.2, and the number of patients receiving insulin decreased from 18 (35%) to 3 (6%) (all p < 0.001). The rate of resolution of type 2 diabetes was 71%. Estimated mean annual per-patient medication costs decreased from $508.56 to $79.17 (p < 0.001). Potential overall health care savings could total $3769 per patient in the first year, decreasing to $1734 at 10 years. Conclusion: Roux-en-Y gastric bypass resulted in significant improvement in diabetic control, with a reduction in hypoglycemic medication use and associated costs in the early postoperative period. Potentially, large indirect and direct cost savings can be realized in the longer term.