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

Laboratory HbA _1c 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 _1c 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 _1c , allowing the calculation of person-specific adjusted HbA _1c (aHbA _1c ). 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 _1c and laboratory HbA _1c 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 _1c and laboratory HbA _1c showed clinically relevant differences. This suggests that the widely used measurement of HbA _1c can underestimate or overestimate diabetes complication risks, which may have future clinical implications.
Competing Interests: YX YX is an employee of Abbott Diabetes Care, RB RMB has received research support, has acted as a consultant, or has been on the scientific advisory board for Abbott Diabetes Care, Ascensia, DexCom, Eli Lilly, Hygieia, Johnson & Johnson, Medtronic, Merck, Novo Nordisk, Onduo, Roche, Sanofi and United Healthcare. RMB's employer, non-profit HealthPartners Institute, contracts for his services and no personal income goes to RMB. TD TCD is an employee of Abbott Diabetes Care, RA RAA received no payment for this work but has had research support and/or Honoraria from Abbott Diabetes Care, NovoNordisk, Eli Lilly, Johnson & Johnson, Boehringer Ingelheim, Bayer, Sanofi and AstraZeneca.
(© 2021, Xu et al.)