title: Association of glycation gap with mortality and vascular complications in diabetes.
abstract: OBJECTIVE
  The "glycation gap" (G-gap), an essentially unproven concept, is an empiric measure of disagreement between HbA1c and fructosamine, the two indirect estimates of glycemic control. Its association with demographic features and key clinical outcomes in individuals with diabetes is uncertain.
  
  
  METHODS
  The G-gap was calculated as the difference between measured HbA1c and a fructosamine-derived standardized predicted HbA1c in 3,182 individuals with diabetes. The G-gap's associations with demographics and clinical outcomes (retinopathy, nephropathy, macrovascular disease, and mortality) were determined.
  
  
  RESULTS
  Demographics varied significantly with G-gap for age, sex, ethnic status, smoking status, type and duration of diabetes, insulin use, and obesity. A positive G-gap was associated with retinopathy (odds ratio 1.24 [95% CI 1.01-1.52], P=0.039), nephropathy (1.55 [1.23-1.95], P<0.001), and, in a subset, macrovascular disease (1.91 [1.18-3.09], P=0.008). In Cox regression analysis, the G-gap had a "U"-shaped quadratic relationship with mortality, with both negative G-gap (1.96 [1.50-2.55], P<0.001) and positive G-gap (2.02 [1.57-2.60], P<0.001) being associated with a significantly higher mortality.
  
  
  CONCLUSIONS
  We confirm published associations of G-gap with retinopathy and nephropathy. We newly demonstrate a relationship with macrovascular and mortality outcomes and potential links to distinct subpopulations of diabetes.
authors.affiliation: Corresponding author: Ananth U. Nayak, ananth.nayak@nhs.net.
authors.forename: Ananth U
authors.initials: AU
authors.lastname: Nayak
authors.forename: Alan M
authors.initials: AM
authors.lastname: Nevill
authors.forename: Paul
authors.initials: P
authors.lastname: Bassett
authors.forename: Baldev M
authors.initials: BM
authors.lastname: Singh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003922:Diabetes Mellitus, Type 1 / Q000150:complications* / Q000378:metabolism / Q000401:mortality*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000378:metabolism / Q000401:mortality*; D003928:Diabetic Nephropathies / Q000378:metabolism; D003930:Diabetic Retinopathy / Q000378:metabolism; D005260:Female; D019270:Fructosamine / Q000378:metabolism*; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D019270:Fructosamine; D006442:Glycated Hemoglobin