To Örebro University

OBJECTIVE: The aim of this study was to determine long-term changes in pharmacological treatment of type 2 diabetes after primary Roux-en-Y gastric bypass (RYGB) surgery, in patients with and without pharmacological treatment of diabetes preoperatively.

SUMMARY OF BACKGROUND DATA: Several studies have shown that gastric bypass has good effect on diabetes, at least in the short-term. This study is a nationwide cohort study using Swedish registers, with basically no patients lost to follow-up during up to 7 years after surgery.

METHODS: The effect of RYGB on type 2 diabetes drug treatment was evaluated in this nationwide matched cohort study. Participants were 22,047 adults with BMI ≥30 identified in the nationwide Scandinavian Surgical Obesity Registry, who underwent primary RYGB between 2007 and 2012. For each individual, up to 10 general population comparators were matched on birth year, sex, and place of residence. Prescription data were retrieved from the nationwide Swedish Prescribed Drug Register through September 2015. Incident use of pharmacological treatment was analyzed using Cox regression.

RESULTS: Sixty-seven percent of patients with pharmacological treatment of type 2 diabetes before surgery were not using diabetes drugs 2 years after surgery and 61% of patients were not pharmacologically treated up to 7 years after surgery. In patients not using diabetes drugs at baseline, there were 189 new cases of pharmacological treatment of type 2 diabetes in the surgery group and 2319 in the matched general population comparators during a median follow-up of 4.6 years (incidence: 21.4 vs 27.9 per 10,000 person-years; adjusted hazard ratio 0.77, 95% confidence interval 0.67-0.89; P < 0.001).

CONCLUSIONS: Gastric bypass surgery not only induces remission of pharmacological treatment of type 2 diabetes but also protects from new onset of pharmacological diabetes treatment. The effect seems to persist in most, but not all, patients over 7 years of follow-up.