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Diabetes Standards of Care & Clinical Practice Resources

Diagnosis of Type 2 Diabetes and Prediabetes

Patients with blood glucose levels higher than normal, but not high enough to be considered diabetes, are at increased risk for developing diabetes. Patients with either impaired fasting glucose or impaired glucose tolerance have been referred to as having "prediabetes." Providers are encouraged to identify patients at increased risk for diabetes so they can start or intensify efforts to prevent progression to diabetes.

Type 2 diabetes can be diagnosed in one of four ways: hemoglobin A1C, fasting plasma glucose, two-hour oral glucose tolerance test, or casual plasma glucose. The criteria for diagnosis of type 2 diabetes and identifying patients at increased risk for diabetes, including corresponding diagnostic values, are presented below.

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Diagnosis of Type 2 Diabetes and Prediabetes Sections

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Clinical Practice Recommendations


Recommendations for Diagnosing Type 2 Diabetes

  • Use the criteria below to diagnose type 2 diabetes in non-pregnant patients:
    • Hemoglobin A1C (A1C) ≥ 6.5% or
    • Fasting plasma glucose (FPG) ≥ 126 mg/dL, where FPG is defined as no caloric intake for at least 8 hours or
    • 2-hour oral glucose tolerance test (OGTT) ≥ 200 mg/dL or
    • Casual plasma glucose ≥ 200 mg/dL with symptoms of hyperglycemia, where "casual" is defined as any time of day without regard to time of last meal.
  • In the absence of unequivocal hyperglycemia, confirm a positive result by repeat testing.

Note: While it is acceptable to screen for diabetes using a point-of-care (POC) capillary A1C and/or glucose, diabetes should only be diagnosed using laboratory-run tests. In addition, the A1C test alone may be less accurate when used to diagnose diabetes in youth.

Recommendations for Identifying Patients at Increased Risk for Diabetes

  • Use the following criteria to identify patients at increased risk for diabetes:
    • Impaired fasting glucose (IFG) defined as FPG 100-125 mg/dL or
    • Impaired glucose tolerance (IGT) defined as 2-hour OGTT 140-199 mg/dL or
    • A1C 5.7-6.4%.

Recommendations for Testing for Diabetes/Prediabetes in AI/AN Adults

  • Test AI/AN adults at least every 3 years.
  • Consider testing more frequently in patients with additional risk factors, including:
    • Overweight/obese (Body Mass Index [BMI] ≥ 25 kg/m2)
    • Family history of type 2 diabetes in first degree relative
    • History of gestational diabetes (GDM)
    • Polycystic ovarian syndrome (PCOS)
    • Cardiovascular disease (CVD)
    • Hypertension
    • HDL cholesterol < 35 mg/dL and/or triglycerides > 250 mg/dL
    • Acanthosis nigricans

Recommendations for Testing for Diabetes/Prediabetes in AI/AN Youth

  • Test overweight AI/AN youth (BMI > 85th percentile) with any of the following risk factors:
    • Family history of diabetes
    • Signs of insulin resistance or conditions associated with it [e.g., acanthosis nigricans, polycystic ovarian syndrome (PCOS), hypertension, dyslipidemia, or small-for-gestational-age (SGA) birth weight]
    • Maternal history of diabetes or gestational diabetes during child's gestation.
  • Start testing at-risk children at age 10 years (or younger if puberty occurs earlier).
  • Test at-risk children ≤ every 3 years.

Note: In patients who present with hyperglycemic symptoms, testing for diabetes is warranted regardless of risk factors listed above.

Clinician and Educator Resources

Patient Education Resources

Diabetes Basics [PDF – 488 KB]

IHS Division of Diabetes Treatment and Prevention

Diagnosis of Diabetes and Prediabetes Exit Disclaimer: You Are Leaving 

National Institute of Diabetes and Digestive and Kidney Diseases