Addressing shortfalls of laboratory HbA<sub>1c</sub> using a model that incorporates red cell lifespan.

Xu, Yongjin; Bergenstal, Richard M; Dunn, Timothy C; Ajjan, Ramzi A · Elife · 2021

prospective_cohort · Level II

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Abstract

Laboratory HbA<sub>1c</sub> does not always predict diabetes complications and our aim was to establish a glycaemic measure that better reflects intracellular glucose exposure in organs susceptible to complications. Six months of continuous glucose monitoring data and concurrent laboratory HbA<sub>1c</sub> were evaluated from 51 type 1 diabetes (T1D) and 80 type 2 diabetes (T2D) patients. Red blood cell (RBC) lifespan was estimated using a kinetic model of glucose and HbA<sub>1c</sub>, allowing the calculation of person-specific adjusted HbA<sub>1c</sub> (aHbA<sub>1c</sub>). Median (IQR) RBC lifespan was 100 (86-102) and 100 (83-101) days in T1D and T2D, respectively. The median (IQR) absolute difference between aHbA<sub>1c</sub> and laboratory HbA<sub>1c</sub> was 3.9 (3.0-14.3) mmol/mol [0.4 (0.3-1.3%)] in T1D and 5.3 (4.1-22.5) mmol/mol [0.5 (0.4-2.0%)] in T2D. aHbA<sub>1c</sub> and laboratory HbA<sub>1c</sub> showed clinically relevant differences. This suggests that the widely used measurement of HbA<sub>1c</sub> can underestimate or overestimate diabetes complication risks, which may have future clinical implications.

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