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 (PM 2.5) 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 PM 2.5 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 PM 2.5).

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.