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Screening for Type 2 Diabetes

The purpose of screening is early diagnosis and treatment. Screening tests are administered to people without current symptoms, but who may be at high risk for certain diseases or conditions.

Screening Guidelines

Prediabetes is characterized by high blood glucose levels that are not high enough to be diagnosed as diabetes. The condition often progresses to type 2 diabetes.

In order to detect prediabetes and type 2 diabetes, the American Diabetes Association (ADA) recommends the following guidelines:

  • Screen adults of any age who are overweight or obese with one or more of these risk factors:
    • First-degree relative with diabetes
    • Low high-density lipoprotein (HDL) (good) cholesterol level and high triglycerides levels
    • High blood pressure
    • History of diabetes during pregnancy (gestational diabetes) or having a baby weighing over nine pounds (4.1 kg)
    • Having polycystic ovary syndrome or other conditions associated with insulin resistance
    • Being inactive
    • History of cardiovascular disease
    • Belonging to an at-risk ethnic group (African American, Hispanic, Native American, Hispanic American, Asian American, or Pacific Islander)
    • Previous blood test results that show HbA1c levels at 5.7% or higher, impaired glucose tolerance, and impaired fasting glucose
  • Screen adults aged 45 and older with or without risk factors
  • Screen overweight children aged 10 years and older who have 2 or more of the following risk factors:
    • Family history of diabetes
    • Mother with diabetes or gestational diabetes
    • Signs of insulin resistance or having a condition associated with insulin resistance
    • At-risk ethnic background

If the results are normal for both adults and children, the ADA recommends screening again in 3 years.

Screening Tests

HbA1c Test

The HbA1c test is a good indicator of your average blood glucose levels over the past 2-4 months. This test usually does not require any dietary restrictions.

Diagnosis HbA1c Level
Prediabetes 5.7%-6.4%
Diabetes 6.5% or higher
Fasting Plasma Glucose

With this blood test, you need to fast (not eat anything) for at least 8 hours before the test.

Diagnosis Fasting Plasma Glucose Level
Prediabetes 100-125 mg/dL (5.6-6.9 mmol/L)
Diabetes 126 mg/dL (7 mmol/L) or higher
Two-Hour Oral Glucose Tolerance Test

After fasting overnight, the doctor tests your glucose level. You are then asked to drink 75 grams of glucose dissolved in water. Two hours later, the doctor tests your glucose level again.

Diagnosis Glucose Levels
Prediabetes 140-199 mg/dL (7.8-11 mmol/L)
Diabetes 200 mg/dL (11.1 mmol/L) or higher


Diabetes mellitus type 2 in adults. EBSCO DynaMed Plus website. Available at: Updated August 29, 2016. Accessed October 5, 2016.

Glucose tests. Lab Tests Online—American Association for Clinical Chemstry website. Available at: Updated December 15, 2015. Accessed August 23, 2016.

Prediabetes. EBSCO DynaMed Plus website. Available at: Updated May 16, 2016. Accessed October 5, 2016.

Statistics about diabetes. American Diabetes Association website. Available at: Updated April 1, 2016. Accessed August 23, 2016.

2/15/2010 DynaMed Plus Systematic Literature Surveillance American Diabetes Association. Standards of medical care in diabetes—2010. Diabetes Care. 2010;(33 Suppl 1):S11-S61.

2/15/2010 DynaMed Plus Systematic Literature Surveillance American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2010;(33 Suppl 1):S62-S69.