Screening for Type 2 Diabetes: What to Know

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 start having symptoms.

• The pancreas doesn't make enough of a hormone called insulin.
• Cells in the body don't respond the right way to insulin that the body makes (insulin resistance).

Normally, insulin lets blood sugar enter cells in the body. The cells use blood sugar for energy.

Insulin resistance or lack of insulin causes extra blood sugar to build up in the blood instead of going into cells. This leads to high blood sugar levels (hyperglycemia). This can cause many problems.

You may be screened for type 2 diabetes as part of your regular health care, especially if you're at high risk for diabetes. Screening can help to find type 2 diabetes at its early stage (prediabetes). Finding and treating prediabetes may delay or prevent you from getting type 2 diabetes.

What are the risk factors for type 2 diabetes?

Risk factors you can change

• Being overweight.
• Having obesity.
• Not being active enough. This means you exercise less than 3 times a week.
• Having high blood pressure.
• Having low levels of good cholesterol (HDL-C).
• Having high levels of blood fats (triglycerides).

Risk factors you can't change

• Being older than age 45.
• Having a parent or sibling with diabetes.
• Being African American, Hispanic/Latino, Native American, Alaska Native, Asian, or Pacific Islander.
• Having heart disease.
• Having acanthosis nigricans. This is dark patches of skin on your neck, armpits, or groin.
• Having a health problem like polycystic ovary syndrome (PCOS).
• Having diabetes while you're pregnant.

Who should be screened for type 2 diabetes?

Adults

• If you're overweight or have obesity and any risk factors.
• If you have prediabetes.
• If you have normal blood sugar levels and 2 or more risk factors.
• If you had diabetes while pregnant.
• If you're age 35 or older.

Children and teens

• If they're overweight and have any of these risk factors:
  • A family member with type 2 diabetes.
  • Being a member of a high-risk ethnic group.
  • Signs of insulin resistance.
  • Problems linked to insulin resistance.
  • A mother who had gestational diabetes while pregnant.

Tell a health care provider about:

• All medicines you take. These include vitamins, herbs, eye drops, and creams.
• Any bleeding problems you have.
• Any medical problems you have.
• Whether you're pregnant or may be pregnant.

What happens during screening for type 2 diabetes?

• Your activity level.
• Any medical problems you have.
• The health of your parents and siblings.
• Past pregnancies, if you're female.

Your provider will also do a physical exam. This includes a blood pressure check and blood tests.

• A fasting blood glucose (FBG) test. You won't be allowed to eat (you'll fast) for 8 hours or more before a blood sample is taken.
• A random blood glucose test. This checks your blood sugar at any time of day, no matter when you ate.
• An oral glucose tolerance test (OGTT). This measures your blood sugar at 2 times:
  • After you haven't eaten (have fasted) overnight. This is your baseline glucose level.
  • 2 hours after you drink a drink that has glucose in it.
• An A1C (hemoglobin A1C) blood test. This helps to find out about blood sugar control over the past 2–3 months.

What do the results mean?

Your test results are a measure of how much glucose is in your blood. Normal blood glucose levels mean you don't have diabetes or prediabetes. High blood glucose levels may mean you have prediabetes or diabetes.

• 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 over 200 mg/dL (11.1 mmol/L).

Talk with your provider about what your results mean. More tests may be needed.