PlasmaGlukose

Plasmaglukose, or plasma glucose, is the concentration of glucose in blood plasma, the liquid component of blood from which cells and clotting factors have been removed. It reflects carbohydrate metabolism and is routinely measured in clinical laboratories. Plasma glucose can be reported in millimoles per liter (mmol/L) or milligrams per deciliter (mg/dL); 1 mmol/L is approximately 18 mg/dL.

Normal fasting plasma glucose typically falls within 3.9–5.5 mmol/L (70–99 mg/dL). Fasting values of 5.6–6.9 mmol/L (100–125 mg/dL) are termed impaired fasting glucose, and a fasting level ≥7.0 mmol/L (≥126 mg/dL) on two occasions supports a diagnosis of diabetes. For the oral glucose tolerance test, plasma glucose is measured two hours after a 75 g glucose load, with a value ≥11.1 mmol/L (200 mg/dL) indicating diabetes.

Measurement methods rely on enzymatic assays, most commonly hexokinase or glucose oxidase reactions, performed on plasma or plasma-equivalent samples. In laboratories, plasma glucose is preferred over whole-blood glucose for accuracy; values are typically about 10–15% higher than capillary whole-blood measurements due to hematocrit effects.

Pre-analytical factors can influence results: recent meals alter fasting status; glycolysis by red blood cells can lower glucose if samples are not processed promptly, so fluoride/oxalate tubes or rapid plasma separation are recommended, and samples should be kept chilled or processed promptly. Conditions such as pregnancy, illness, or certain medications can also affect glucose levels.

Plasma glucose testing is used to screen for and monitor diabetes, assess hypoglycemia, and guide treatment, complementing measures such as HbA1c and the oral glucose tolerance test.