Endocrine Journal
Online ISSN : 1348-4540
Print ISSN : 0918-8959
ISSN-L : 0918-8959
The ratio of glycated albumin to hemoglobin A1c measured in IFCC units accurately represents the glycation gap
Junya AkatsukaMie MochizukiIkuma MushaAkira OhtakeKisho KobayashiToru KikuchiNobuyuki KikuchiTomoyuki KawamuraTatsuhiko UrakamiShigetaka SugiharaTadao HoshinoShin Amemiya
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2015 Volume 62 Issue 2 Pages 161-172


The glycation gap (G-gap: difference between measured hemoglobin A1c [A1C] and the value predicted by its regression on the fructosamine level) is stable and associated with diabetic complications. Measuring A1C level in International Federation of Clinical Chemistry (IFCC) units (A1C-SI; mmol/mol) and National Glycohemoglobin Standardization Program units (A1C-NGSP; %) and using glycated albumin (GA) level instead of fructosamine level for calculating the G-gap, we investigated whether the G-gap is better represented by GA/A1C ratio if expressed in SI units (GA/A1C-SI ratio) rather than in NGSP units (GA/A1C-% ratio). We examined 749 Japanese children with type 1 diabetes using simultaneous GA and A1C measurements. Of these, 369 patients were examined more than five times to assess the consistency of the G-gap and the GA/A1C ratio within individuals. The relationship of GA/A1C-% ratio to the corresponding A1C-NGSP was stronger than that of GA/A1C-SI ratio to A1C-IFCC. At enrollment, the inverse relationship between the GA/A1C-SI ratio and G-gap was highly significant (R2 = 0.95) compared with that between the GA/A1C-% ratio and G-gap (R2 = 0.69). A highly significant inverse relationship was also observed between the mean GA/A1C-SI ratio and the mean G-gaps obtained individually over time (R2 = 0.95) compared with that using the corresponding A1C-NGSP (R2 = 0.67). We conclude that the G-gap is better represented by the GA/A1C-SI ratio. We propose the use of mean GA/A1C-SI ratios easily obtained individually over time as reference values in Japanese children with type 1 diabetes (6.75 ± 0.60 [means ± SD]).

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