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.