HbA1c → estimated average glucose (eAG)
Conversion of HbA1c to average plasma glucose using ADAG equations. Supports NGSP (%) and IFCC (mmol/mol) units.
About this calculator
Conversion of HbA1c to estimated average glucose (eAG). Formula from the ADAG study (Nathan et al., Diabetes Care, 2008) in 507 patients: eAG (mg/dL) = 28.7 × HbA1c – 46.7. In mmol/L: eAG = 1.59 × HbA1c – 2.59. Clinical use. Translating lab HbA1c into glucose units understandable to the patient – helps interpret results and discuss targets. For example, HbA1c 7% corresponds to mean glucose about 8.6 mmol/L (154 mg/dL); HbA1c 8% – 10.2 mmol/L (183 mg/dL). HbA1c targets (ADA 2024, ESC 2023). <7% – most adults with T2DM. <6.5% – young patients with short diabetes duration without comorbidities (if achievable without hypoglycemia). <8% – older patients with limited life expectancy or severe comorbidities. Individualize by hypoglycemia risk, diabetes duration, life expectancy. Limitations. The formula fails in conditions altering red cell metabolism: hemolytic anemia, hemoglobinopathies (HbS, HbC, HbE, beta-thalassemia), uremia, recent blood loss, transfusion, iron deficiency under treatment. In such patients HbA1c under- or overestimates mean glycemia – use continuous glucose monitoring (CGM) with Time in Range, or alternative marker fructosamine. In pregnant women with gestational diabetes, fasting and postprandial targets matter more than HbA1c.
Source
Formula version: nathan-2008-v1
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