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The History of HbA1c

Iranian-American biochemist Samuel Rahbar first described elevated glycated hemoglobin in diabetic patients back in 1968, noticing an unusual extra hemoglobin fraction that appeared consistently more abundant in people with diabetes than in healthy individuals tested alongside them. The test remained a research curiosity for years until the landmark Diabetes Control and Complications Trial, published in 1993, definitively proved that tighter blood sugar control, as tracked directly through HbA1c, meaningfully reduced the long-term risk of diabetic eye, kidney, and nerve damage in patients followed for years. That trial cemented HbA1c as the gold standard for monitoring glycemic control, and in 2009 an international expert committee went a crucial step further, recommending HbA1c also be used to diagnose diabetes itself, a role once reserved almost exclusively for direct blood glucose testing alone.

What HbA1c Actually Is

HbA1c refers to hemoglobin, the oxygen-carrying protein inside red blood cells, that has become permanently bound to glucose molecules circulating in the bloodstream, a slow chemical process that happens naturally and continuously throughout a red blood cell's roughly 120-day lifespan. Because glucose attaches to hemoglobin in rough proportion to how much sugar has been present in the blood over that entire period, HbA1c effectively functions as a running average of blood sugar control spanning the preceding two to three months, rather than reflecting any single moment in time. This long-term view makes HbA1c far less susceptible to the day-to-day fluctuations that can distort a single fasting glucose reading, which is precisely why it has become the preferred tool for both diagnosing and monitoring diabetes over time.

How HbA1c Is Measured

HbA1c is most commonly measured using high-performance liquid chromatography, a technique that separates the glycated and non-glycated hemoglobin fractions based on their subtly different chemical properties, allowing laboratories to precisely calculate exactly what percentage of total hemoglobin has become glycated. Other laboratories instead use immunoassay or boronate affinity methods, which rely on antibodies or specialized binding molecules that selectively recognize the glycated hemoglobin fraction directly within a blood sample tested. Since the 1990s, the National Glycohemoglobin Standardization Program has worked to ensure that HbA1c results stay consistent across different laboratories and testing methods nationwide, a genuinely important effort given how heavily modern treatment decisions increasingly depend on this single, remarkably powerful number.

Scientists Behind the Science

Samuel Rahbar's original 1968 discovery provided the essential biochemical foundation without which none of HbA1c's later clinical applications could possibly have developed, identifying the core phenomenon decades before anyone fully appreciated its tremendous diagnostic value in ordinary medical practice. The many researchers behind the Diabetes Control and Complications Trial then transformed that biochemical curiosity into unmistakable clinical proof, definitively demonstrating that HbA1c wasn't merely a convenient laboratory number but a genuinely meaningful predictor of real, serious long-term diabetes complications in patients everywhere. Together, this combined body of foundational discovery and rigorous, painstaking clinical validation transformed HbA1c from an obscure biochemical footnote into one of the single most consequential laboratory tests in all of modern chronic disease management today.