# The association between indoor biofuel use for cooking and glucose metabolism in adults: A cross-sectional study in Tanzania

## TL;DR

This study finds that using biofuels for indoor cooking in Tanzania is linked to impaired insulin production, potentially increasing diabetes risk.

## Contribution

The study identifies a novel association between household air pollution from biofuel use and β-cell dysfunction in Tanzanian adults.

## Key findings

- Moderate and high exposure to HAP was linked to a two-fold higher risk of reduced insulin production.
- No significant associations were found with insulin resistance, pre-diabetes, or diabetes.
- The study highlights the need for longitudinal research with objective HAP measurements.

## Abstract

The burden of type 2 diabetes is rapidly increasing in low- and middle-income countries (LMICs), but determinants are not well-characterized. Household air pollution (HAP) from indoor biofuel use for cooking has been associated with non-communicable diseases and could be contributing to the increasing burden of diabetes in LMICs, though data are limited. We assessed the association between indoor biofuel use for cooking and glucose metabolism in HIV-infected and HIV-uninfected Tanzanian adults. This cross-sectional analysis included Tanzanian adults with and without HIV, from whom we collected sociodemographic and non-communicable disease risk factor data. The main predictor variable was indoor biofuel use for cooking, established using self-reported cooking location (indoor or outdoor) and fuel type (electricity/gas or biomass fuel), and categorized as minimal or no exposure, moderate exposure, and high exposure. Blood glucose and insulin were measured during oral glucose tolerance tests, allowing computation of outcome variables including markers of β-cell dysfunction (homeostatic model assessment-β, insulinogenic index, oral disposition index), insulin resistance (HOMA-IR and Matsuda index), and pre-diabetes and diabetes status. Logistic regression was used to assess associations, adjusting for age, sex, physical activity, smoking, socioeconomic status, HIV status, and body mass index. Among 1,871 participants (mean age 40.6 ± 11.9 years; 59.8% female), those with moderate and high exposure to HAP had approximately two-fold higher odds of a lower insulinogenic index (adjusted odds ratio [aOR] = 2.13, 95% CI: 1.27–3.57 and aOR = 2.31, 95% CI: 1.39–3.83, respectively) compared to those with minimal or no exposure. HAP was not associated with other markers of β-cell function, insulin resistance, pre-diabetes, or diabetes. In conclusion, HAP is associated with increased risk of β-cell dysfunction among individuals using biofuel for indoor cooking. Longitudinal studies using objective HAP measurements are needed to confirm these findings.