Objective: To study the association between ambient air pollutants and serum C-reactive protein (CRP) concentration in 1,392 type 2 diabetic patients in Pune, India.
Research design and methods: A cross-sectional study was conducted that linked daily time series of ambient air pollution data (obtained from central monitoring sites) and plasma CRP concentration in type 2 diabetic patients from the Wellcome Trust Genetic (WellGen) Study, recruited between March 2005 and May 2007. Air pollution effects on CRP concentration were investigated with delays (lags) of 0-7 days and multiday averaging spans of 7, 14, and 30 days before blood collection adjusted for age, sex, BMI, hemoglobin, fasting plasma glucose, treatment with agents with anti-inflammatory action, season, air temperature, and relative humidity.
Results: Median CRP concentration was 3.49 mg/L. For 1 SD increase in SO(2) and oxides of nitrogen (NO(x)) concentrations in ambient air, a day before blood collection (lag(1)), we observed a significant increase in CRP (9.34 and 7.77%, respectively). The effect was higher with lag(2) (12.42% for SO(2) and 11.60% for NO(x)) and wore off progressively thereafter. We also found a significant association with multiday averaging times of up to 30 and 7 days for SO(2) and NO(x), respectively. No significant associations were found between particulate matter with an aerodynamic profile ≤10 µm (PM(10)) and CRP concentration except in summer. The association was significantly higher among patients with a shorter duration of diabetes, and in those not on statin and thiazolidinedione treatment.
Conclusions: We demonstrate, for the first time, a possible contribution of ambient air pollution to systemic inflammation in Indian type 2 diabetic patients. This may have implications for vascular complications of diabetes.