Glycated hemoglobin (A1C) is a key biomarker for glycemic control in diabetes and has an important relationship with glucose. The objective of this study was to evaluate the relationship of real-world laboratory results for patient samples with both glucose and A1C. 213,698 paired glucose and A1C measurements from 709 laboratories in 39 countries were collected January to October 2021. Values within the measuring interval 70 to 400 mg/dL for glucose and 4% to 13% (NGSP) for A1C were analyzed. The pairs were analyzed in twenty equal-sized groups by composite rank order. The summed absolute relative differences (SARD) were compared between best-fit nonlinear and linear models. The group mean values presented a clear nonlinear relationship, with an SARD seven times lower than the best-fit linear model. The nonlinear Michaelis constant for glucose and glucose transporter 1 (GLUT1) was 4mg/dL, which agrees with literature values. The 95% prediction intervals at the diabetes diagnosis levels of 6.5% A1C and 126 mg/dL glucose were narrower for the nonlinear model. This model-based formula allows better prediction of the relationship of glucose and A1C which can lead to improved personalized clinical decisions.
Figure: Nonlinear (left) and linear (right) best-fit models, N = 213,698. Each point represents the mean of approximately n=10,680 paired measurements. Dotted lines are 95% prediction intervals.
T.Dunn: Employee; Abbott. Y.Xu: Employee; Abbott Diabetes. S.Schneider: None. S.Gawel: Employee; Abbott Diagnostics. R.Gopinath: Employee; Abbott Diagnostics. M.Berman: None. A.P.Orzechowski: Employee; Abbott.