title: Variability in hemoglobin A1c predicts all-cause mortality in patients with type 2 diabetes.
abstract: BACKGROUND
  To evaluate the relationship between hemoglobin A1c variability and all-cause mortality in type 2 diabetic patients.
  
  
  METHODS
  This was a retrospective cohort study in type 2 diabetic patients followed for at least 2 years between 2003 and 2009. A1C variability was determined from the standard deviation or coefficient of variation of serial A1C values (A1C(SD) or A1C(CV)). Subjects were categorized into either the high or low A1C variability group according to their A1C(CV) median. Hazard ratios (HRs) of various factors for all-cause mortality were determined from Cox's proportional hazard models.
  
  
  RESULTS
  A total of 881 subjects (422 men, 459 women) were included and 73 (8.3%) died during follow-up. The follow-up period was 4.7 ± 2.3 years. All-cause mortality was higher in subjects with high A1C(CV) (11.0% vs. 5.4%, p=0.002). In the Kaplan-Meier failure curve, subjects with higher A1C(CV) demonstrated a trend of higher mortality (p=0.1). In multivariate Cox's proportional hazards models, A1C(SD) and A1C(CV) significantly predicted all-cause mortality with an HR of 1.987 (p=0.02) and 1.062 (p=0.013), respectively, after adjusting for age, gender, body mass index, duration of diabetes, mean systolic blood pressure, use of antihypertensives and statins, mean LDL-cholesterol, smoking status, chronic kidney disease, and mean A1C values (A1C(MEAN)). The ability of A1C(SD) and A1C(CV) to predict all-cause mortality was more evident in subjects with relatively low A1C(MEAN.)
  
  
  CONCLUSIONS
  A1C variability is an important risk factor for all-cause mortality in type 2 diabetic patients.
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Cardinal Tien Hospital, Xindian, Taiwan.
authors.forename: Wen-Ya
authors.initials: WY
authors.lastname: Ma
authors.forename: Hung-Yuan
authors.initials: HY
authors.lastname: Li
authors.forename: Dee
authors.initials: D
authors.lastname: Pei
authors.forename: Te-Lin
authors.initials: TL
authors.lastname: Hsia
authors.forename: Kuo-Cheng
authors.initials: KC
authors.lastname: Lu
authors.forename: Li-Yu
authors.initials: LY
authors.lastname: Tsai
authors.forename: Jung-Nan
authors.initials: JN
authors.lastname: Wei
authors.forename: Ching-Chieh
authors.initials: CC
authors.lastname: Su
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000401:mortality*; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D006442:Glycated Hemoglobin