HbA1c(A1c)

HbA1c is the standard population-screening test for type 2 diabetes. The diagnostic threshold is 6.5 percent or higher on two occasions, with prediabetes defined as 5.7 to 6.4 percent. For longevity-focused men the optimization target sits well below the prediabetic range. Observational data link HbA1c values above roughly 5.4 to 5.6 percent with elevated cardiovascular and dementia risk, even in patients without diabetes. The estimated average glucose (eAG) corresponding to an HbA1c can be calculated as (28.7 multiplied by HbA1c) minus 46.7 in mg/dL units, giving a translation that helps patients interpret the value. An HbA1c of 5.4 percent maps to an eAG of roughly 108 mg/dL. HbA1c is not infallible. Conditions that shorten red blood cell lifespan (hemolytic anemia, recent blood loss, hemoglobinopathies like sickle cell trait, frequent blood donation) artificially lower the reading. Conditions that lengthen RBC survival (iron deficiency, splenectomy) artificially raise it. In suspected discordance, a serum fructosamine (2 to 3 week window) or continuous glucose monitor (real-time) gives a more accurate picture. For most men, HbA1c paired with fasting insulin and a postprandial glucose check provides a solid metabolic baseline.