Systemic Inflammation (C-Reactive Protein) in Type 2 Diabetic Patients Is Associated With Ambient Air Pollution in Pune City, India

Abstract

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.