title: Air pollution and risk of type 2 diabetes mellitus: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Whether exposure to relatively high levels of air pollution is associated with diabetes occurrence remains unclear. We sought to assess and quantify the association between exposure to major air pollutants and risk of type 2 diabetes.
  
  
  METHODS
  PubMed and EMBASE databases (through September 2013) were searched using a combination of terms related to exposure to gaseous (NO2 and NOx) or particulate matter pollutants (PM2.5, PM10 and PM10-2.5) and type 2 diabetes. Descriptive and quantitative information were extracted from selected studies. We used random-effects models meta-analysis to derive overall risk estimates per type of pollutant.
  
  
  RESULTS
  We included ten studies (five cross-sectional and five prospective), assessing the effects of air pollutants on the occurrence of diabetes. In prospective investigations, the overall effect on diabetes occurrence was significant for both NO2 (adjusted hazard ratio [HR], 1.13; 95% confidence interval [95%CI], 1.01-1.22; p < 0.001; I(2) = 36.4%, pheterogeneity = 0.208) and PM2.5 (HR, 1.11; 95%CI, 1.03-1.20; p < 0.001; I(2) = 0.0%, pheterogeneity = 0.827). Odds ratios were reported by two cross-sectional studies which revealed similar associations between both NO2 and PM2.5 with type 2 diabetes. Across studies, risk estimates were generally adjusted for age, gender, body mass index and cigarette smoking.
  
  
  CONCLUSIONS
  Available evidence supports a prospective association of main air pollutants with an increased risk for type 2 diabetes. This finding may have implications for population-based strategies to reduce diabetes risk.
authors.affiliation: Diabetes Research Center, Faculty of Medicine and Pharmacy, Brussels Free University, Brussels, Belgium.
authors.forename: Eric V
authors.initials: EV
authors.lastname: Balti
authors.affiliation: Hubert Department of Global Health, Rollins School of Public Health, Emory University; Atlanta, GA, USA; MedStar Hospital System, Baltimore, MD, USA.
authors.forename: Justin B
authors.initials: JB
authors.lastname: Echouffo-Tcheugui
authors.affiliation: Non-Communicable Diseases Research Unit, South African Medical Research Council, Cape Town, South Africa; Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, Cape Town, South Africa.
authors.forename: Yandiswa Y
authors.initials: YY
authors.lastname: Yako
authors.affiliation: Non-Communicable Diseases Research Unit, South African Medical Research Council, Cape Town, South Africa; Department of Medicine, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa; The George Institute for Global Health, The University of Sydney, Sydney, Australia. Electronic address: andre.kengne@mrc.ac.za.
authors.forename: Andre P
authors.initials: AP
authors.lastname: Kengne
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects*; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000209:etiology*; D014943:Global Health; D006801:Humans; D015994:Incidence; D052638:Particulate Matter; D012307:Risk Factors
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: Air pollution; Gaseous pollutants; Inflammation; Insulin resistance; Particulate matters pollutants; Type 2 diabetes