Plasmaglucose

Plasmaglucose, more commonly called plasma glucose, is the concentration of glucose in the plasma—the liquid portion of blood from which cells and clotting factors have been separated. It is a key biomarker of carbohydrate metabolism and is routinely used in diagnosing and monitoring conditions such as diabetes and hypoglycemia. The term plasmaglucose is sometimes encountered in older or nonstandard texts but refers to the same measurement as plasma glucose.

Measurement and units

Plasma glucose is reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). Common clinical tests include fasting plasma glucose (FPG), random plasma glucose, and the 2-hour plasma glucose (2h-PG) after an oral glucose tolerance test (OGTT). Point-of-care devices often estimate plasma glucose from capillary blood, with values that may differ slightly from laboratory measurements.

Diagnostic thresholds (typical criteria)

- Fasting plasma glucose: normal <100 mg/dL (5.6 mmol/L); impaired fasting glucose 100–125 mg/dL (5.6–6.9 mmol/L); diabetes ≥126 mg/dL (7.0 mmol/L) on two occasions.

- 2-hour plasma glucose after a 75 g OGTT: normal <140 mg/dL (7.8 mmol/L); impaired glucose tolerance 140–199 mg/dL (7.8–11.0 mmol/L); diabetes ≥200 mg/dL (11.1 mmol/L).

- Random plasma glucose ≥200 mg/dL (11.1 mmol/L) with classic hyperglycemia symptoms can indicate diabetes.

Clinical use and interpretation

Plasma glucose informs diagnosis of diabetes and prediabetes, guides treatment decisions, and helps monitor glycemic control in individuals with diabetes. It is affected by recent meals, stress, illness, and medications, and pre-analytical factors such as sample handling and glycolysis can influence results.

Measurement methods

Laboratories commonly use enzymatic assays (glucose oxidase or hexokinase) to quantify plasma glucose. Point-of-care devices are useful for rapid monitoring but may require confirmatory laboratory testing for diagnostic purposes.