Neighborhood Walkability and the Development of Type 2 Diabetes After Gestational Diabetes Mellitus: A Longitudinal Study in New York City

OBJECTIVE: Neighborhood walkability is associated with lower gestational diabetes mellitus (GDM) risk, but its association with type 2 diabetes after GDM is unknown. We estimated this association and assessed effect modification by individual and neighborhood socioeconomic conditions. RESEARCH DESIGN AND METHODS: Women with GDM who delivered in New York City (NYC) in 2009-2011 were identified through birth certificate records and hospital discharge data and linked to NYC A1C Registry data (2009-2021) for follow-up. Women with prepregnancy diabetes were excluded. A previously published neighborhood walkability index was categorized into quartiles. Type 2 diabetes was ascertained as two A1C results ≥6.5% (48 mmol/mol) after 12 weeks postpartum. Cox proportional hazards models estimated associations between walkability and type 2 diabetes after GDM, adjusting for individual- and neighborhood-level characteristics. Stratification analyses were conducted by socioeconomic conditions. RESULTS: Among 12,403 women with GDM at baseline, the 12-year cumulative incidence of type 2 diabetes was 20.6%. Adjusted hazard ratios (aHRs) of type 2 diabetes for low-medium (aHR 0.89 [95% CI 0.76, 1.04]), medium (aHR 0.85 [95% CI 0.74, 0.99]), and high (aHR 0.88 [95% CI 0.76, 1.03]) walkability (vs. low) were protective or null. The protective association from high walkability was observed only in the most affluent neighborhoods (aHR 0.52 [95% CI 0.31, 0.89]). CONCLUSIONS: In NYC, more walkable neighborhoods were associated with lower risk of type 2 diabetes after GDM without a dose-response effect, and associations depended on individual and neighborhood socioeconomic contexts. While increasing walkability is a core planning goal and may improve health, decisions should also address neighborhood inequities in diabetes.