title: The impact of ambient temperature on HbA1c in Taiwanese type 2 diabetic patients: The most vulnerable subgroup.
abstract: OBJECTIVE
  The relationship between temperature variability and HbA1c has been reported in Caucasians, but not for Asians of Taiwanese origin. This study investigated the impact of temperature on HbA1c in various groups of Taiwanese with type 2 diabetes in Taiwan.
  
  
  METHODS
  For this longitudinal follow-up study which started in 2006, we recruited a total of 4399 patients with type 2 diabetes who had been regularly followed up at Chi Mei Medical Center and obtained local temperature data for 2006 to 2011 from Taiwan's Central Weather Bureau. We used a generalized estimated equation (GEE) to analyze the HbA1c level and its change over time with temperature and temperature changes, respectively.
  
  
  RESULTS
  We found a negative correlation between HbA1c and temperature (R = -0.475, p = 0.001). For every 1°C decrement in temperature, there was an increase in the risk of having a HbA1c level >7% [p < 0.001, adjusted odds ratio (OR): 1.01]. There was a significantly higher risk of HbA1c > 7% among those in the lowest quartile of temperatures than the highest quartile (p = 0.0038, adjusted OR: 1.13). Patients with diabetic patients were at higher risk of HbA1C > 7% in the winter and spring than those in the summer (adjusted OR: 1.13, p = 0.0027; adjusted OR: 1.14, p = 0.0022). After adjusting for various confounders, we found people who were younger than 65 years old, people who had diabetes for longer than 6 years, and people who had a body mass index (BMI) < 24 to be more susceptible to temperature changes (p = 0.0022, β: 0.0095; p < 0.0001, β: 0.0125; p < 0.0001, β: 0.016, respectively).
  
  
  CONCLUSIONS
  Our study suggests cold weather may adversely affect HbA1c levels in Taiwanese people with type 2 diabetes, especially in people under 65 years old, people with diabetes for longer than 6 years, and those with a BMI < 24.
authors: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chi Mei Medical Center, Tainan, Taiwan; Department of Senior Citizen Service Management, Chia Nan University of Pharmacy and Science, Tainan, Taiwan.
authors: Kai-Jen
authors: KJ
authors: Tien
authors: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chi Mei Medical Center, Tainan, Taiwan.
authors: Chwen-Yi
authors: CY
authors: Yang
authors: Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan; Department of Hospital and Health Care Administration, Chia Nan University of Pharmacy and Science, Tainan, Taiwan.
authors: Shih-Feng
authors: SF
authors: Weng
authors: Department of Nursing, Chi Mei Medical Center, Tainan, Taiwan.
authors: Su-Yen
authors: SY
authors: Liu
authors: Division of Endocrinology and Metabolism, Department of Internal Medicine, Changhua Christian Hospital, Changhua, Taiwan; Graduate Institute of Integrated Medicine, China Medical University, Taiwan.
authors: Ming-Chia
authors: MC
authors: Hsieh
authors: Division of Endocrinology and Metabolism, Department of Internal Medicine, Chi Mei Medical Center, Tainan, Taiwan. Electronic address: cacmmc@gmail.com.
authors: Chien-Wen
authors: CW
authors: Chou
mesh_terms: D000368:Aged; D001786:Blood Glucose; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D013624:Taiwan; D013696:Temperature
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin
keywords: HbA1c; Taiwanese; temperature; type 2 diabetes