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Diabetes Standards of Care & Clinical Practice Resources

Diagnosing Type 2 Diabetes and Identifying Prediabetes

The American Diabetes Association and the World Health Organization have established uniform criteria for diagnosing type 2 diabetes and identifying people with prediabetes. Type 2 diabetes can be diagnosed in one of four ways: measuring A1C, fasting plasma glucose, and random plasma glucose levels or performing an oral glucose tolerance test. Risk assessment tools are available to determine whether an individual should be tested for diabetes or prediabetes.

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Clinical Practice Recommendations

 

Diabetes risk assessment tools can be used to identify asymptomatic individuals at increased risk for diabetes, and determine if a diagnostic test should be performed.

Use one of the criteria below to diagnose type 2 diabetes in non-pregnant people:

  • A1C level of 6.5% or higher
  • Fasting plasma glucose (FPG) level of 126 mg/dL or higher, after the person has had no caloric intake overnight for at least 8 hours
  • 2-hour plasma glucose (PG) level of 200 mg/dL or higher with a 75-gm oral glucose tolerance test
  • Random plasma glucose test result of 200 mg/dL or higher in people with symptoms of hyperglycemia, such as increased thirst, increased urination, unexplained weight loss, fatigue, or blurred vision

Two abnormal results from the same or different tests are required for diagnosis (e.g. two A1C levels ≥ 6.5% or an A1C value ≥ 6.5% and an FPG test result ≥ 126 mg/dL). However, a single random test result of 200 mg/dL or higher in a person with symptoms is diagnostic for diabetes.

Although point-of-care capillary A1C and/or glucose tests can be used to screen people for diabetes, only laboratory-run tests should be used for diagnosis.

People with prediabetes have blood glucose levels that are above the normal range but not elevated to meet the criteria for diabetes. An individual with prediabetes may also have other risk factors related to diabetes such as obesity, abnormal blood lipid levels, and high blood pressure.

Use any one of the following criteria to identify people with prediabetes.

  • A1C level of 5.7% to 6.4%
  • Fasting plasma glucose level of 100 mg/dL to 125 mg/dL
  • 2-hour plasma glucose value of 140 mg/dL to 199 mg/dL during a 75-gm oral glucose tolerance test

Test for diabetes in asymptomatic adults, and then every 3 years thereafter.

Consider testing adults more often if they have additional risk factors (such as those listed below):

  • Overweight/obese (body mass index [BMI] ≥ 25 kg/m2)
  • Physical inactivity
  • Type 2 diabetes in a first-degree relative
  • History of gestational diabetes
  • History of cardiovascular disease
  • Signs of insulin resistance or conditions associated with it (e.g., acanthosis nigricans, polycystic ovarian syndrome, hypertension, or dyslipidemia with HDL cholesterol level lower than 35 mg/dL and/or triglycerides level higher than 250 mg/dL)

Test people with prediabetes for diabetes each year.

Test overweight and obese youth (those with a BMI in the 85th percentile or higher) at the onset of puberty or after age 10 years (whichever comes first), and then every 3 years thereafter.

Consider testing children and adolescents more frequently if they have additional risk factors, such as:

  • Increasing BMI over time
  • Maternal history of diabetes or gestational diabetes during the child's gestation
  • Family history of diabetes
  • Signs of insulin resistance or conditions associated with it (e.g., acanthosis nigricans, polycystic ovarian syndrome, hypertension, dyslipidemia, or small-for-gestational-age birth weight)

Test children and adolescents with prediabetes for diabetes each year.

Clinician and Educator Resources

Diabetes Educators Lesson Plan: Information about Type 2 Diabetes [PDF – 421 KB]

IHS Division of Diabetes Treatment and Prevention


American Diabetes Association. 2. Classification and Diagnosis of Diabetes: Standards of Medical Care in Diabetes 2021 Exit Disclaimer: You Are Leaving www.ihs.gov  Diabetes Care 2021;44(Suppl.1):S15-S33. doi:10.2337/dc21-S002

American Diabetes Association


Diabetes & Prediabetes Tests Exit Disclaimer: You Are Leaving www.ihs.gov 

National Institute of Diabetes and Digestive and Kidney Diseases


Diabetes Tests Exit Disclaimer: You Are Leaving www.ihs.gov 

Centers for Disease Control and Prevention

Patient Education Resources

Diabetes Basics [PDF – 488 KB]

Information About Type 2 Diabetes [PDF – 506 KB]

IHS Division of Diabetes Treatment and Prevention


Diagnosis of Diabetes and Prediabetes Exit Disclaimer: You Are Leaving www.ihs.gov 

National Institute of Diabetes and Digestive and Kidney Diseases