title: Discordance in the levels of hemoglobin A1C and glycated albumin: Calculation of the glycation gap based on glycated albumin level.
abstract: OBJECTIVE
  The glycation gap (G-gap) is an empirical measure of the extent of the difference between HbA1C and fructosamine levels. Several studies have shown that the presence of a G-gap is linked to diabetic nephropathy, but possible artifacts caused by dependence of the fructosamine level on the extent of serum protein metabolism require careful consideration. We investigated the consistency of G-gaps measured by assaying glycated albumin (GA) levels to identify factors associated with G-gap variations.
  
  
  METHODS
  A total of 457 pairs of observations, like an HbA1c and GA measurement at the same clinic visit, were obtained from 170 Korean patients with type 2 diabetes. HbA1c and GA levels were measured simultaneously in two or three separate occasions. Each G-gap was calculated as the difference between the measured HbA1c level and that predicted by the GA level. All patients underwent abdominal computed tomography, and the areas of subcutaneous and visceral fat were measured.
  
  
  RESULTS
  The G-gaps were all significantly inter-correlated over time (γ=0.755, P<0.001).The direction of each G-gap was consistent. The body mass index (BMI), visceral fat area, and the estimated glomerular filtration rate (eGFR) increased linearly from the lowest to the highest G-gap quartile (all P values <0.05). Upon multivariate analysis, both visceral fat area and the eGFR were significantly associated with a G-gap.
  
  
  CONCLUSIONS
  A G-gap determined using GA measurements is consistent within an individual over time. The G-gap is associated with visceral fat and kidney function in patients with type 2 diabetes.
authors.affiliation: Department of Internal Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Mee Kyoung
authors.initials: MK
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Kyung-Jin
authors.initials: KJ
authors.lastname: Yun
authors.affiliation: Department of Internal Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Hyuk-Sang
authors.initials: HS
authors.lastname: Kwon
authors.affiliation: Department of Internal Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Ki Hyun
authors.initials: KH
authors.lastname: Baek
authors.affiliation: Department of Internal Medicine, The Catholic University of Korea, Seoul, Korea. Electronic address: kihos@catholic.ac.kr.
authors.forename: Ki-Ho
authors.initials: KH
authors.lastname: Song
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications / Q000378:metabolism; D003928:Diabetic Nephropathies / Q000097:blood / Q000175:diagnosis; D018450:Disease Progression; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis* / Q000378:metabolism; D017127:Glycation End Products, Advanced; D006031:Glycosylation; D006801:Humans; D050152:Intra-Abdominal Fat / Q000473:pathology; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea; D012709:Serum Albumin / Q000032:analysis* / Q000378:metabolism; D000093423:Glycated Serum Albumin
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D017127:Glycation End Products, Advanced; D012709:Serum Albumin; D000093423:Glycated Serum Albumin
keywords: Fructosamine; Glycated albumin; Glycation gap; Kidney function; Visceral fat