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The History of Glucose

Glucose was first isolated in 1747 by German chemist Andreas Marggraf, who extracted it from raisins, though sugars themselves had been used by humans for millennia before their chemical identity was ever understood. Its name comes from the Greek word "glykys," meaning sweet, coined by French chemist Jean-Baptiste Dumas in 1838. Long before that, physicians in ancient India and Egypt had already noticed that some people's urine attracted ants or tasted sweet — a symptom eventually named "diabetes mellitus," meaning honey-sweet, by English physician Thomas Willis in 1674. For centuries afterward, a sweet-urine test was essentially the only way to detect the disease at all.

What Glucose Actually Is

Glucose is a simple sugar, or monosaccharide, with the chemical formula C6H12O6, and it's the primary source of energy for nearly every cell in the human body, including the brain, which relies on it almost exclusively under normal conditions. After eating, the digestive system breaks carbohydrates down into glucose, which enters the bloodstream and is either used immediately for energy or stored as glycogen in the liver and muscles for later use. Two hormones — insulin and glucagon, both produced by the pancreas — work in opposition to keep blood glucose within a narrow, stable range: insulin lowers it by helping cells absorb glucose from the blood, while glucagon raises it by triggering the liver to release its stored glycogen back into circulation.

How Glucose Is Measured

The most common laboratory method today is the hexokinase method, considered the reference standard for accuracy in clinical labs, which uses an enzyme to convert glucose into a precisely measurable byproduct. An older technique, the glucose oxidase method, is still widely used in point-of-care devices and home glucometers because it's fast and inexpensive, relying on a simple electrochemical reaction on a disposable test strip. Beyond a single snapshot reading, continuous glucose monitors — small sensors worn under the skin — now track levels every few minutes throughout the day, and HbA1c testing offers a different kind of measurement entirely: rather than one moment in time, it reflects average blood sugar over roughly the past three months by measuring how much glucose has attached itself to red blood cells.

Scientists Behind the Science

French physiologist Claude Bernard made one of the most important 19th-century discoveries about glucose, showing in the 1850s that the liver stores and releases sugar as glycogen — a finding that helped establish the very concept of the body's internal, self-regulating environment. The most transformative breakthrough came in 1921, when Canadian researchers Frederick Banting and Charles Best, working alongside James Collip and John Macleod at the University of Toronto, successfully isolated insulin, turning a once-fatal diagnosis into a manageable condition almost overnight; Banting and Macleod received the Nobel Prize in Physiology or Medicine in 1923. Decades earlier, German chemist Emil Fischer had painstakingly determined glucose's precise molecular structure, work recognized with a Nobel Prize in Chemistry in 1902 and foundational to all later biochemical understanding of how the body handles sugar.