OBJECTIVES: Glycemic control as measured by hemoglobin A1c (HbA1c) is an important outcome in evaluations of the real-world effectiveness of bariatric surgery (BxS) in patients with type 2 diabetes mellitus (T2DM), but cannot be assessed directly in insurance claims data. This study assessed whether cessation of antihyperglycemic medication following BxS is an acceptable proxy for glycemic control without continued use of antihyperglycemic medication.

METHODS: Patients age≥18yr who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy from 2005Q1 through 2015Q2 were selected from the de-identified Optum Integrated Claims/EHR database. Patients were required to have (a) health plan enrollment for 180d pre-BxS (baseline) and 2yr post-BxS; (b) BMI≥30, diagnosed T2DM, and an antihyperglycemic medication fill during baseline; and (c) HbA1c measured both at baseline and during 366-730d post-BxS. Post-BxS glycemic control (HbA1c<7%; <6% as sensitivity analysis) was assessed using first HbA1c measure during 366-730d post-BxS; antihyperglycemic cessation was defined as zero antihyperglycemic medication fills during 366-730d post-BxS.

RESULTS: 80 T2DM patients on antihyperglycemic therapy who underwent BxS were eligible for inclusion (baseline characteristics: 55% RYGB; 45% sleeve gastrectomy; median age=55yr; 63% female; median BMI=44.7; 39% insulin users; 40% with HbA1c<7%; 10% with HbA1c<6%). During 366-730d post-BxS, 52 patients (65%) ceased use of antihyperglycemic medications; among this group, 92% had HbA1c<7% and 70% had HbA1c<6% post-BxS. Among the 28 patients who continued using antihyperglycemic medications 366-730d post-BxS, 50% had HbA1c<7% and 14% had HbA1c<6% post-BxS. Among the 31 baseline insulin users, 77% discontinued insulin following BxS, of whom 79% had HbA1c<7% and 50% had HbA1c<6% post-BxS.

CONCLUSIONS: Cessation of antihyperglycemic medication following BxS was an accurate proxy for glycemic control without continued use of antihyperglycemic medication in 70-90% of cases, depending on the definition used for glycemic control.