Table 1.

FPG for the diagnosis of diabetes

Advantages

• Glucose assay easily automated

• Widely available

• Inexpensive

• Single sample

Disadvantages

• Patient must fast ≥8 h

• Large biological variability

• Diurnal variation

• Sample not stable

• Numerous factors alter glucose concentrations, e.g., stress, acute illness

• No harmonization of glucose testing

• Concentration varies with source of the sample (venous, capillary, or arterial blood)

• Concentration in whole blood is different from that in plasma

• Guidelines recommend plasma, but many laboratories measure serum glucose

• FPG less tightly linked to diabetes complications (than A1C)

• Reflects glucose homeostasis at a single point in time