Contents lists available at ScienceDirect International Journal of Hygiene and Environmental Health journal homepage: www.elsevier.com/locate/ijheh Effects of long-term exposure to CO and PM 2.5 on microalbuminuria in type 2 diabetes Wei-Shan Chin a , Yu-Kang Chang b , Li-Feng Huang c , Hung-Chang Tsui d , Chih-Cheng Hsu c,e,f, ⁎ ,1 , Yue-Liang Leon Guo a,d, ⁎ ,1 a National Institute of Environmental Health Science, National Health Research Institutes, 35 Keyan Road, Zhuan, Miaoli County 35053, Taiwan, ROC b Department of Medical Research, Tung’s Taichung Metro Harbor Hospital, No. 699, Sec. 8, Taiwan Blvd., Taichung City, 435, Taiwan, ROC c Institute of Population Health Sciences, National Health Research Institutes, 35 Keyan Road, Zhuan, Miaoli County 35053, Taiwan, ROC d Department of Environmental and Occupational Medicine, National Taiwan University (NTU) College of medicine and NTU Hospital, No.1, Changde St., Zhongzheng Dist., Taipei City 10048, Taiwan, ROC e Department of Health Services Administration, China Medical University, No. 91, Hsueh-Shih Road, Taichung, Taiwan 40402, Taiwan, ROC f Department of Family Medicine, Min-Sheng General Hospital, No.168, ChingKuo Rd, 330 Taoyuan, Taiwan, ROC ARTICLE INFO Keywords: Air pollution CO PM 2.5 microalbuminuria Type 2 diabetes (T2DM) Diabetic nephropathy ABSTRACT Objective: No study has examined the effects of air pollutants on albuminuria in type 2 diabetes. Therefore, the present study investigated this association. Methods: This follow-up study enrolled 812 patients with type 2 diabetes between 2003 and 2012. The urinary albumin-to-creatinine ratio (ACR) was recorded annually. Exposure to the air pollutants CO, NO 2 ,O 3 , SO 2 , and PM 2.5 was interpolated from 72 air-quality monitoring stations to residences by using the kriging method. The association between air pollutants and ACR increase was assessed using mixed-effect model with random in- tercepts for 36 clinics. Results: The study objects (mean age: 55.4 years) were followed for 3 or more years (average period: 5.4 years). ACR increase was found to be positively associated with the male sex, baseline hemoglobin A1c, and exposure to CO and PM 2.5 , and negatively associated with waist circumference through multiple linear regression. Annually urine albumin/creatinine ratio increase was estimated by the final model, Patients exposed to higher levels of CO (e.g., third quartile, 1025 ppb) and lower levels of CO (e.g., first quartile, 850 ppb) had an annual ACR increase of 3.73 and 3.54 mg/g, respectively. Patients exposed to higher levels of PM 2.5 (e.g., third quartile, 38.8 μg/M3) and lower levels of PM 2.5 (e.g., first quartile, 27.7 μg/M3) had an annual ACR increase of 3.96 and 3.17 mg/g, respectively. Conclusions: Exposure to high CO and PM 2.5 levels increased albuminuria in type 2 diabetes. 1. Introduction The World Health Organization estimated that the number of people with diabetes mellitus worldwide would increase from 285 million in 2015 to 439 million by 2030 (Shaw et al., 2010). The increase is mainly in type 2 diabetes mellitus (T2DM) (The World Health Organization, 2016). Diabetic nephropathy, a common complication of T2DM, occurs in approximately 30%–50% of patients with T2DM (Gheith et al., 2016; Remuzzi et al., 2002). The progression of diabetic nephropathy can lead to end-stage renal disease, which is a crucial cause of death worldwide (Jha et al., 2013; Wang et al., 2016). Nephropathy is a pertinent factor for poor prognosis among patients with diabetes and can be staged as hyperfiltration, silent, incipient, overt nephropathy, and end-stage renal disease (Pugliese, 2014). Microalbuminuria may begin at the si- lent nephropathy stage, with its progression marking the worsening of nephropathy (Pugliese, 2014). The remission or regression of micro- albuminuria in patients with diabetes reduces morbidity and mortality (Araki et al., 2007; Gerstein, 2001). Therefore, controlling micro- albuminuria is critical for preventing nephropathy progression in dia- betes. Established factors for the development or deterioration of albu- minuria are poor control of hyperglycemia, hypertension, and smoking (Ritz and Orth 1999). Studies on the association between albuminuria and air pollution are lacking, despite the suggestion that air pollutants https://doi.org/10.1016/j.ijheh.2018.04.009 Received 15 December 2017; Received in revised form 21 April 2018; Accepted 21 April 2018 ⁎ Corresponding authors. 1 These authors contributed equally. E-mail addresses: weishanlinda@gmail.com (W.-S. Chin), yogurt8306@gmail.com (Y.-K. Chang), 030203@nhri.org.tw (L.-F. Huang), tracyperf@gmail.com (H.-C. Tsui), cch@nhri.org.tw (C.-C. Hsu), leonguo@ntu.edu.tw (Y.-L.L. Guo). International Journal of Hygiene and Environmental Health xxx (xxxx) xxx–xxx 1438-4639/ © 2018 Elsevier GmbH. All rights reserved. Please cite this article as: Chin, W.-S., International Journal of Hygiene and Environmental Health (2018), https://doi.org/10.1016/j.ijheh.2018.04.009