Particulate matter and markers of glycemic control and insulin resistance in type 2 diabetic patients: result from Wellcome Trust Genetic study.

There is growing evidence that air pollution is associated with increased risk of type 2 diabetes (T2DM). However, information related to whether particulate matter (PM) contributing to worsened metabolic control in T2DM patients is inconsistent. We examined the association of PM10 exposure with glucose-function parameters in young-onset T2DM patients. We investigated the association between a year ambient concentration of PM10 at residential places, using AERMOD dispersion model, with fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), 2 h post meal plasma glucose (2hPG), homeostasis model assessment of insulin resistance (HOMA-IR), β-cell function (HOMA-β) and disposition index (DI) in 1213 diabetic patients from the Wellcome Trust Genetic study at the Diabetes Unit, KEM Hospital Research Center, Pune, India. We used linear regression models and adjusted for a variety of individual and environmental confounding variables. Possible effect modification by age, gender, waist-to-hip ratio (WHR) and smoking status were investigated. Sensitivity analysis assessed the impact of relative humidity (RH) and temperature a day before examination and anti-diabetic and HHR medication (Hydralazine, Hydrochlorothiazide and Reserpine). We found that 1 SD increment in background concentration of PM10 at residential places (43.83 µg/m3) was significantly associated with 2.25 mmol/mol and 0.38 mmol/l increase in arithmetic means of HbA1c and 2hPG, respectively. A similar increase in PM10 was also associated with 4.89% increase in geometric mean of HOMA-IR. The associations remained significant after adjustment to RH and temperature, and WHR and smoking enhanced the size of the effect. Our study suggests that long-term exposure to PM10 is associated with higher glycaemia and insulin resistance. In context of our previous demonstration of association of SO2 and NO x and plasma C-reactive protein, we suggest that air pollution could influence progression of diabetes complications. Prospective studies and interventions are required to define mechanism and confirm causality.