866-P: Estimated HbA1c Discordance: Should Estimated HbA1c Be Derived from Time-in-Range or Mean Glucose Levels?

Abstract

In patients with hypoglycemia, estimated HbA1c (eA1c) derived from the percentage of time in range [TIR] (reference range, 70-180 mg/dL) using reported formulae may be overestimated. We examined eA1c derived from TIR (TIR-eA1c) and eA1c derived from mean glucose levels (mean-eA1c). In this cross-sectional study, we analyzed 24-h glucose levels measured from 00:00 to 24:00 during hospitalization using a continuous glucose monitor (iPro2) in 119 patients with type 2 diabetes. We calculated TIR-eA1c and mean-eA1c for these 119 patients using the reported following formulae: TIR-eA1c 1 = 10.31 - 0.048 × TIR; TIR-eA1c 2 = (TIR - 155.4) ÷ -12.762; mean-eA1c 1 = (mean glucose level + 46.7) ÷ 28.7; and mean-eA1c 2 (proposed as the glucose management indicator) = 3.31 + 0.02392 × mean glucose level. The values of TIR-eA1c 1 - mean-eA1c 1 [Δ1], TIR-eA1c 2 - mean-eA1c 1 [Δ2], TIR-eA1c 1 - mean-eA1c 2 [Δ3], and TIR-eA1c 2 - mean-eA1c 2 [Δ4] were also evaluated. An increase in the percentage of time below range (< 70 mg/dL) [TBR < 70] was significantly associated with increased Δ1, Δ2, Δ3, and Δ4. The presence of hypoglycemia was significantly associated with Δ1 > 0.5%, Δ2 > 0.5%, Δ3 > 0.5%, and Δ4 > 0.5% (Table). Overall, our results show that mean-eA1c should be used as the indicator of HbA1c in patients with hypoglycemia. Disclosure S. Takeishi: None. H. Tsuboi: None.