title: Seasonality and temperature effects on fasting plasma glucose: A population-based longitudinal study in China.
abstract: OBJECTIVE
  To examine the seasonality and effects of temperature on levels of fasting plasma glucose (FPG).
  
  
  METHODS
  We collected health data from the Kailuan cohort study. FPG, blood pressure and individual information including age, gender, body mass index, smoking status, drinking habit, physical activities, income, work type, education level, and history of diabetes, were collected for each participant. Daily weather conditions were collected during the study period of 2006-2011. A total of 49,417 participants who had three times of health examination were included to the analyses. Generalized additive mixed models were used to examine the effects of temperature and seasonality on FPG levels, while controlling for potential confounders.
  
  
  RESULTS
  FPG level was higher in winter and spring than that in autumn and summer. For all participants, the FPG winter level increased 0.31mmol/L [95% confidence interval (CI), 0.28-0.33mmol/L] in comparison with autumn. The association between temperature and FPG levels was U-shaped. For all participants, the change in FPG levels associated with extreme cold temperature (-6.7°C), moderate cold temperature (2.4°C), moderate hot temperature (23.7°C), and with extreme hot temperature (28.1°C), in comparison with threshold (18.1°C) were 0.12mmol/L (95% CI: 0.10-0.14mmol/L), 0.10 (95% CI: 0.09-0.12mmol/L), 0.06 (95% CI: 0.04-0.08mmol/L), and 0.12mmol/L (95% CI: 0.08-0.16mmol/L), respectively.
  
  
  CONCLUSIONS
  The findings suggest that there may be strong relationships between FPG levels and season and ambient temperature. In particular, there were higher FPG levels in the winter and at extreme cold and hot temperatures.
authors: School of Public Health, The University of Queensland, Brisbane, Queensland, Australia. Electronic address: uqshandy0106@gmail.com.
authors: S
authors: S
authors: Li
authors: Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China. Electronic address: yongzhou78214@163.com.
authors: Y
authors: Y
authors: Zhou
authors: School of Public Health, The University of Queensland, Brisbane, Queensland, Australia. Electronic address: g.williams@sph.uq.edu.au.
authors: G
authors: G
authors: Williams
authors: Center for Environmental and Respiratory Health Research, Faculty of Medicine, University of Oulu, Oulu, Finland. Electronic address: jouni.jaakkola@oulu.fi.
authors: J J K
authors: JJ
authors: Jaakkola
authors: State Key Laboratory of Organ Failure Research, Department of Biostatistics, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, China. Electronic address: ouchunquan@hotmail.com.
authors: C
authors: C
authors: Ou
authors: Department of Cardiology, Kailuan General Hospital, Tangshan, Hebei Province, China. Electronic address: chenshuohua0106@126.com.
authors: S
authors: S
authors: Chen
authors: Department of Occupational Disease Prevention and Treatment, Kailuan General Hospital, Tangshan, Hebei Province, China. Electronic address: ytc1963@163.com.
authors: T
authors: T
authors: Yao
authors: Department of Occupational Disease Prevention and Treatment, Kailuan General Hospital, Tangshan, Hebei Province, China. Electronic address: 13831591818@126.com.
authors: T
authors: T
authors: Qin
authors: Department of Cardiology, Kailuan General Hospital, Tangshan, Hebei Province, China. Electronic address: drwusl@163.com.
authors: S
authors: S
authors: Wu
authors: School of Public Health, The University of Queensland, Brisbane, Queensland, Australia. Electronic address: y.guo1@uq.edu.au.
authors: Y
authors: Y
authors: Guo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000378:metabolism*; D002681:China; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000097:blood; D005215:Fasting / Q000097:blood*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012621:Seasons; D013696:Temperature; D055815:Young Adult
chemical_list: D001786:Blood Glucose
keywords: Diabetes; Fasting plasma glucose; Seasonality; Temperature effect