Myths vs facts: HbA1c and longevity

HbA1c (glycated hemoglobin) is a well-established marker of average blood glucose over the past 2–3 months, primarily used for diabetes diagnosis and management. In longevity research, lower HbA1c is often associated with reduced biological aging, but the evidence is nuanced. Epidemiological studies link elevated HbA1c with increased all-cause mortality, even in non-diabetic ranges. However, extremely low HbA1c (e.g., <5.0%) is not automatically beneficial: it may reflect frequent hypoglycemia, iron deficiency, or hemoglobin variants that distort the result. Moreover, HbA1c is not a direct longevity marker but a risk indicator for metabolic dysregulation. The myth that deliberately lowering HbA1c to an 'optimal' level extends lifespan is not supported by randomized long-term trials. Instead, HbA1c should be interpreted alongside fasting glucose, insulin resistance, lifestyle, and individual genetics. For an evidence-based longevity strategy, stable moderately low values (around 5.0–5.5%) with good glycemic variability are sensible – not chasing the lowest number. Caveat: For individuals with diabetes or prediabetes, personalized target ranges apply.