Is HbA1c useful for longevity?

HbA1c (glycated hemoglobin) is a well-established biomarker reflecting average blood glucose over the past 2–3 months. Strong epidemiological evidence links elevated HbA1c to increased risk of cardiovascular disease, diabetes complications, and premature mortality. For longevity, maintaining HbA1c in the lower normal range (approximately 5.0–5.6% / 31–38 mmol/mol) is favorable, indicating stable glucose regulation and low glycemic stress. However, HbA1c is not a standalone predictor – genetics, lifestyle, inflammation markers, and other biomarkers (e.g., insulin, triglycerides) are equally important. The evidence is human-strong, but based on observational studies; long-term randomized trials directly testing HbA1c reduction on lifespan are lacking. Additionally, conditions like anemia or hemoglobin variants can distort results. For individual longevity assessment, HbA1c is useful but insufficient – it must be interpreted within a comprehensive metabolic profile. Caveat: extremely low HbA1c may signal hypoglycemia or underlying disease.