How is glucose measured?

Updated: Jul 22, 2021
  • Author: Setu K Patolia, MD, MPH; Chief Editor: Sridevi Devaraj, PhD, DABCC, FAACC, FRSC, CCRP  more...
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Glucose is measured by various enzymatic methods. The hexokinase/glucose-6-phosphate dehydrogenase (G6PD) method developed by the American Association for Clinical Chemistry has been accepted as the reference method for glucose determination. Other methods include the copper reduction method (modified Folin Wu), the o-toluidine method, glucose oxidase assay, and the glucose oxidase and peroxidase (GOD-POD) method. [7, 8]

Hexokinase/G6PD method

The hexokinase/G6PD method is described here as it is used most widely. Glucose is phosphorylated by hexokinase in the presence of ATP to form glucose-6-phosphate. The enzyme G6PD converts glucose-6-phosphate into 6-phosphogluconate, with nicotinamide adenine dinucleotide (NAD+) concurrently reduced to NADH. Every micromole of glucose consumed produces one micromole of NADH. Absorbing light at 340 nm, NADH can be identified via spectrophotometric detection of increased absorbance. [5]

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