BACKGROUND: Type 2 diabetes mellitus (T2DM) resolves in >80% of patients after Roux-en-Y gastric bypass (RYGB). It has been hypothesized that foregut exclusion is mechanistically important to this observation. This study aimed to determine whether gastrogastric (GG) fistula, with a loss of foregut exclusion, is associated with T2DM relapse, and to assess whether closure of GG fistula is associated with T2DM resolution.

STUDY DESIGN: A matched cohort study of patients who experienced T2DM remission after RYGB. Cases (patients with GG fistula) were matched to controls (patients without GG fistula) based on age, BMI, weight regain, and duration from RYGB. Primary end point was T2DM relapse. Time-to-event analysis was performed to identify an association between GG fistula and time to T2DM resolution.

RESULTS: One hundred and twenty-six patients (42 cases and 84 controls) were included. Cases experienced a higher rate of T2DM relapse than controls (48% vs 13%; odds ratio 18; p < 0.0001). On multivariable analysis, GG fistula remained a significant predictor of T2DM relapse after controlling for sex and insulin use (odds ratio 6.3; p = 0.02). Of the 42 cases, 20 experienced T2DM relapse, with 1 spontaneous resolution. Of 19, thirteen underwent fistula revision and experienced a higher rate of T2DM resolution than the nonrevision group (69% vs 0%; odds ratio 27; p = 0.036). Time to T2DM resolution was shorter in the revision group compared with the nonrevision group (p = 0.006).

CONCLUSIONS: The RYGB patients with GG fistula have a higher rate of T2DM relapse, compared with those without GG fistula with similar BMI and weight regain. Successful fistula revision is associated with resolution of T2DM.