HbA1c (Glycated Hemoglobin)
The average glucose of the last 90 days — and a longevity marker
Definition
HbA1c is the fraction of haemoglobin that has reacted non-enzymatically with glucose, reflecting the average glycaemia of the last 60-90 days (erythrocyte half-life). It is the reference biomarker for diagnosis and follow-up of diabetes (≥6.5% defines diabetes) and pre-diabetes (5.7-6.4%), but in longevity medicine it is interpreted more strictly: 'normal-high' values (5.5-5.7%) are already associated with higher cardiovascular risk and mortality compared with optimal values (<5.2%).
Detailed explanation
The association between HbA1c and mortality is U-shaped: very low (<5.0%) in the presence of anaemia, renal failure, or malnutrition predicts higher mortality; very high predicts diabetic complications. The longevity optimum sits at 5.0-5.3%.
Interpretation limitations: HbA1c is altered with anaemia (underestimates), polycythaemia or recent transfusions (overestimates), pregnancy (underestimates), haemoglobinopathies (variable), and individual erythrocyte turnover rate. When HbA1c and CGM disagree, CGM is preferred as the real glycaemia reference.
The relationship between HbA1c and AGEs (advanced glycation end-products): HbA1c is essentially an AGE specific to haemoglobin; chronically elevated values predict generalised AGE accumulation in collagen, blood vessels, and nerve tissue, manifesting as accelerated atherosclerosis, neuropathy, and cutaneous deterioration (the 'caramelised' skin of the diabetic).
Interventions to optimise HbA1c: low-glycaemic-load diet, 16:8 intermittent fasting, resistance + Zone 2 exercise, control of free fructose, potentially useful supplements (berberine, myo-inositol, alpha-lipoic acid), monitoring with CGM at least 1 month/year to identify individual triggers.
Scientific sources
Related terms
Interested in related treatments?
Generate My Protocol