Screening for Type 2 Diabetes

A screening test for type 2 diabetes (type 2 diabetes mellitus) is a blood test to measure your blood sugar (glucose) level. This test is done to check for early signs of diabetes, before you develop symptoms.

• The pancreas does not make enough of a hormone called insulin.
• Cells in the body do not respond properly to insulin that the body makes (insulin resistance).

Normally, insulin allows blood sugar (glucose) to enter cells in the body. The cells use glucose for energy. Insulin resistance or lack of insulin causes excess glucose to build up in the blood instead of going into cells. This results in high blood glucose levels (hyperglycemia), which can cause many complications.

You may be screened for type 2 diabetes as part of your regular health care, especially if you have a high risk for diabetes. Screening can help to identify type 2 diabetes at its early stage (prediabetes). Identifying and treating prediabetes may delay or prevent the development of type 2 diabetes.

Tell a health care provider about:

• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
• Any bleeding problems you have.
• Any medical conditions you have.
• Whether you are pregnant or may be pregnant.

Who should be screened for type 2 diabetes?

Adults

• Adults age 35 and older. These adults should be screened once every three years.
• Adults who are any age, are overweight, and have one other risk factor. These adults should be screened once every three years.
• Adults who have normal blood glucose levels and two or more risk factors. These adults may be screened once every year (annually).
• Women who have had gestational diabetes in the past. These women should be screened once every three years.
• Pregnant women who have risk factors. These women should be screened at their first prenatal visit and again between weeks 24 and 28 of pregnancy.

Children and adolescents

• Children and adolescents should be screened for type 2 diabetes if they are overweight and have any of the following risk factors:
  • A family history of type 2 diabetes.
  • Being a member of a high-risk ethnic group.
  • Signs of insulin resistance or conditions that are associated with insulin resistance.
  • A mother who had gestational diabetes while pregnant.
• Screening should be done at least once every three years, starting at age 10 or at the onset of puberty, whichever comes first.

Your health care provider or your child's health care provider may recommend having a screening more or less often.

What are the risk factors for type 2 diabetes?

• Not getting enough exercise.
• Having high blood pressure.
• Having low levels of good cholesterol (HDL-C) or high levels of blood fats (triglycerides).
• Having high blood glucose in a previous blood test.
• Being overweight or obese.

• Having a parent or sibling (first-degree relative) who has diabetes.
• Being of American-Indian, African-American, Hispanic/Latino, Asian, or Pacific Islander descent.
• Being older than age 45.
• Having a history of diabetes during pregnancy (gestational diabetes).
• Having certain diseases or conditions that may be caused by insulin resistance, including:
  • Acanthosis nigricans. This is a condition that causes dark skin on the neck, armpits, and groin.
  • Polycystic ovary syndrome (PCOS).
  • Cardiovascular heart disease.

What happens during screening?

• Your health and your risk factors, including your activity level and any medical conditions that you have.
• The health of your first-degree relatives.
• Past pregnancies, if this applies.

• A fasting blood glucose (FBG) test. You will not be allowed to eat (you will fast) for 8 hours or more before a blood sample is taken.
• A random blood glucose test. This test checks your blood glucose at any time of the day regardless of when you ate.
• An oral glucose tolerance test (OGTT). This test measures your blood glucose at two times:
  • After you have not eaten (have fasted) overnight. This is your baseline glucose level.
  • Two hours after you drink a glucose-containing beverage.
• An A1C (hemoglobin A1C) blood test. This test provides information about blood glucose control over the previous 2–3 months.

What do the results mean?

Your test results are a measurement of how much glucose is in your blood. Normal blood glucose levels mean that you do not have diabetes or prediabetes. High blood glucose levels may mean that you have prediabetes or diabetes. Depending on the results, other tests may be needed to confirm the diagnosis.

• Your FBG level is 126 mg/dL (7.0 mmol/L) or higher.
• Your random blood glucose level is 200 mg/dL (11.1 mmol/L) or higher.
• Your A1C level is 6.5% or higher.
• Your OGTT result is higher than 200 mg/dL (11.1 mmol/L).

These blood tests may be repeated to confirm your diagnosis. Talk with your health care provider about what your results mean.

Summary

• A screening test for type 2 diabetes (type 2 diabetes mellitus) is a blood test to measure your blood sugar (glucose) level.
• Know what your risk factors are for developing type 2 diabetes.
• If you are at risk, get screening tests as often as told by your health care provider.
• Screening may help you identify type 2 diabetes at its early stage (prediabetes). Identifying and treating prediabetes may delay or prevent the development of type 2 diabetes.