title: HbA1c variability is associated with microalbuminuria development in type 2 diabetes: a 7-year prospective cohort study.
abstract: OBJECTIVE
  HbA(1c) variability has been shown to be an independent risk factor for nephropathy in patients with type 1 diabetes. In this study, we aimed to explore the association between HbA(1c) variability and microalbuminuria development in patients with type 2 diabetes. We also intended to test the applicability of serially measured HbA(1c) over 2 years for this risk assessment.
  
  
  METHODS
  Between 2003 and 2005, we recruited 821 middle-aged normoalbuminuric individuals with type 2 diabetes and followed them through to the end of 2010. The average follow-up time was 6.2 years. We defined microalbuminuria as a urine albumin to creatinine ratio of 30 mg/g (3.4 mg/mmol) or higher. HbA(1c) variability was calculated by the SD of serially measured HbA(1c). The Cox proportional hazards model was used to evaluate the association between HbA(1c) SD quartile and development of microalbuminuria.
  
  
  RESULTS
  The incidence of microalbuminuria for the overall population was 58.4, 58.6, 60.8 and 91.9 per 1,000 person-years for Q1- to Q4-adjusted HbA(1c) SD, respectively (p for trend = 0.042). Compared with patients in Q1, those in Q4 were about 37% more likely to develop microalbuminuria. The HR derived from a series of 2 year HbA(1c) measurements was similar to that from data collection for longer than 4 years.
  
  
  CONCLUSIONS
  In addition to mean HbA(1c) values, HbA(1c) variability, even measured as early as 2 years, is independently associated with the development of microalbuminuria in patients with type 2 diabetes.
authors.affiliation: Division of Preventive Medicine and Health Services Research, Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan.
authors.forename: C C
authors.initials: CC
authors.lastname: Hsu
authors.forename: H Y
authors.initials: HY
authors.lastname: Chang
authors.forename: M C
authors.initials: MC
authors.lastname: Huang
authors.forename: S J
authors.initials: SJ
authors.lastname: Hwang
authors.forename: Y C
authors.initials: YC
authors.lastname: Yang
authors.forename: Y S
authors.initials: YS
authors.lastname: Lee
authors.forename: S J
authors.initials: SJ
authors.lastname: Shin
authors.forename: T Y
authors.initials: TY
authors.lastname: Tai
mesh_terms: D000419:Albuminuria / Q000453:epidemiology / Q000652:urine*; D000704:Analysis of Variance; D001786:Blood Glucose / Q000378:metabolism*; D003404:Creatinine / Q000652:urine*; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology / Q000378:metabolism* / Q000503:physiopathology; D003928:Diabetic Nephropathies / Q000453:epidemiology / Q000378:metabolism* / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D003404:Creatinine; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human