Impact of the wood-burning Justa cookstove on glycated hemoglobin (HbA1c): a stepped-wedge randomized trial in rural Honduras.

BACKGROUND Type 2 diabetes is a rapidly growing global health challenge in low- and middle-income countries (LMICs), and evidence suggests that air pollution exposure contributes. Household air pollution from burning solid fuels for cooking is a major burden in LMICs but studies demonstrating associations between reductions in household air pollution and improvements in HbA1c, a biomarker of diabetes risk, are lacking. We previously reported substantial reductions in fine particulate matter (PM2.5) and black carbon concentrations following an intervention in rural Honduras with the Justa cookstove, a wood-burning stove with an engineered combustion chamber and chimney. OBJECTIVE In a stepped-wedge randomized controlled trial among 230 Honduran women using traditional wood-burning stoves at baseline, we evaluated the effect of the Justa intervention on HbA1c and characterized the longitudinal associations between air pollution exposures and HbA1c. METHODS At each of 6 visits over 3 years, we measured 24-hour PM2.5 and black carbon concentrations, and finger-stick HbA1c levels. We used linear mixed models in intent-to-treat (condition by assigned stove type), exposure-response (using 24-hour measures and modeled estimates of long-term exposures), and "per protocol" self-reported stove use analyses. RESULTS HbA1c was reduced for the Justa condition compared to the traditional stove condition, but estimates were small and not statistically significant (-0.03 percentage points, 95% confidence interval [CI]: -0.13, 0.07, n=1,208 observations). A slightly stronger effect was observed when using self-reported stove use in per protocol analyses. Exposure-response analyses demonstrated positive associations between HbA1c and air pollution (e.g., HbA1c was 0.22 percentage points higher (95% CI: 0.13, 0.30) per log-unit higher long-term average personal PM2.5). DISCUSSION Our study provides novel evidence of exposure-response associations between household air pollution and HbA1c within a randomized cookstove trial, contributing to the evidence base necessary to support clean cooking policy initiatives. https://doi.org/10.1289/EHP15095.