title: Using hemoglobin A1c to derive mean blood glucose in peritoneal dialysis patients.
abstract: BACKGROUND
  Although hemoglobin A1c (HbA1c) has been widely used as a clinical assessment tool for outcome analyses related to glycemic control, the relationship between HbA1c and average blood glucose (BG) specific to peritoneal dialysis (PD) patients with diabetes has not been characterized. We sought to develop HbA1c-BG equation models for PD patients.
  
  
  METHODS
  We examined associations between HbA1c and random serum BG values over time in a contemporary 5-year (2001-2006) cohort of DaVita PD patients with diabetes. We identified 850 patients (mean age: 58 ± 13 years, 56% male) with 4,566 paired measurements of HbA1c and BG. The bootstrapping method was used to estimate average BG and corresponding HbA1c.
  
  
  RESULTS
  Linear regression analyses yielded the following HbA1c-BG equations: (1) BG (mg/dl) = 24.1 + 28.6 × HbA1c - 12.2 × albumin [adjusted R(2) (R(2)adj = 0.454)], (2) BG = 55.3 + 28.8 × HbA1c - 10.2 × albumin - 3.3 × Hb (R(2)adj = 0.457), and (3) BG = 69.5 + 28.7 × HbA1c - 10.1 × albumin - 3.7 × Hb - 0.1 × age + race/ethnicity (-10.1 African Americans, -5.4 other race/ethnicities; R(2)adj = 0.457). All models showed greater explanatory power of BG variation than previously established HbA1c-BG equation models defined within non-PD cohorts [R(2)adj = 0.446 for both the Diabetes Control and Complications Trial (DCCT) and the A1c-Derived Average Glucose (ADAG) equations].
  
  
  CONCLUSIONS
  The association between HbA1c and BG in PD patients is different than that of patients with normal kidney function. Our analysis suggests that equations incorporating serum albumin and/or Hb values better estimate the HbA1c-BG relationship in PD patients compared to equations using HbA1c alone.
authors.affiliation: Harold Simmons Center for Chronic Disease Research and Epidemiology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.
authors.forename: Junichi
authors.initials: J
authors.lastname: Hoshino
authors.forename: Rajnish
authors.initials: R
authors.lastname: Mehrotra
authors.forename: Connie M
authors.initials: CM
authors.lastname: Rhee
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Yamagata
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Ubara
authors.forename: Kenmei
authors.initials: K
authors.lastname: Takaichi
authors.forename: Csaba P
authors.initials: CP
authors.lastname: Kovesdy
authors.forename: Miklos Z
authors.initials: MZ
authors.lastname: Molnar
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
mesh_terms: D000368:Aged; D000465:Algorithms; D001786:Blood Glucose / Q000032:analysis*; D005260:Female; D006442:Glycated Hemoglobin / Q000502:physiology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis; D044382:Population Groups
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human