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. Author manuscript; available in PMC: 2016 Jul 25.
Published in final edited form as: Endocr Pract. 2015 Apr;21(Suppl 1):1–87. doi: 10.4158/EP15672.GL

Table 6. Glucose Testing and Interpretation.

Normal High Risk for Diabetes Diabetes
FPG <100 mg/dL IFG
FPG ≥100-125 mg/dL		 FPG ≥126 mg/dL
2-h PG <140 mg/dL IGT
2-h PG ≥140-199 mg/dL		 2-h PG ≥200 mg/dL
Random PG ≥200 mg/dL +
symptoms
A1C <5.5% 5.5 to 6.4%
For screening of prediabetesa 		≥6.5%
Secondaryb

Abbreviations: A1C = hemoglobin A1C; FPG = fasting plasma glucose; IFG = impaired fasting glucose; IGT = impaired glucose tolerance; PG = plasma glucose.

a

A1C should be used only for screening prediabetes. The diagnosis of prediabetes, which may manifest as either IFG or IGT, should be confirmed with glucose testing.

b

Glucose criteria are preferred for the diagnosis of DM. In all cases, the diagnosis should be confirmed on a separate day by repeating glucose or A1C testing. When A1C is used for diagnosis, follow-up glucose testing should be done when possible to help manage DM.