Blood glucose is generally measured as the venous plasma level. There is a 3-5 mg/mL difference between arterial and venous levels, with higher differences in the postprandial state.Levels are higher in the arterial blood because some of the glucose diffuses from the plasma to interstitial fluid (IF) as blood circulates through the capillary system. Arterial blood glucose and capillary blood glucose have been shown to be almost identical in concentration. Glucose concentrations measured by glucose meters are whole blood levels, which can differ from plasma glucose levels by up to 11% (plasma higher).
