All About Diabetes Screening

Keeping tabs on your blood sugar could save your life.

patient receiving a1c diabetes test from doctor

Updated on November 13, 2023.

When was the last time you had your blood sugar checked? Even if you feel healthy, skipping out on regular screenings is a risky move. You could have high blood sugar and not know it. In fact, about 20 percent of the 37 million people in the United States with diabetes are not diagnosed, according to the Centers for Disease Control and Prevention (CDC). 

It’s a similar situation for those with prediabetes, a condition characterized by higher-than-normal blood sugar that often leads to type 2 diabetes. The CDC estimates that about 80 percent of the 96 million U.S. adults with prediabetes aren’t aware of it.

By testing and monitoring your blood sugar, however, you get a window into where you stand. You may be able prevent the onset of type 2 diabetes, and can treat the condition properly if you’re diagnosed.

Factors that affect screening frequency

Blood sugar tends to creep up as we grow older, so healthcare providers (HCPs) generally recommend testing every three years, starting at age 45. If you are overweight or obese and have one of the diabetes risk factors below, you should be tested earlier and more often; every one to three years. 

  • Sedentary lifestyle: Regularly sitting for long periods of time—be it on the couch or at a desk—increases your risk for diabetes unless you counter this inactivity with regular exercise.
  • Family history of diabetes: If you have a sibling or parent with diabetes, you are at greater risk.
  • Certain racial and ethnic backgrounds: Compared with other groups, African American, Alaska Native, Native American, Latino, Pacific Islander, and Asian American people have higher odds of diabetes.
  • History of specific health problems: If your blood pressure is at or above 140/90 mm Hg, you have unhealthy cholesterol levels, you have cardiovascular disease, or you've previously tested positive for high blood sugar, you're at increased risk of developing diabetes. A history of gestational diabetes or polycystic ovary syndrome raises your chances, as well.

Be aware, too, of symptoms that might indicate diabetes. If you notice a dramatic increase in urination, hunger, thirst, or fatigue—or if you experience sudden, unexplained weight loss or vision changes—reach out to an HCP immediately to schedule a blood sugar test. Many people don’t experience any symptoms, however, so be sure to get tested if you have risk factors, either way. 

Choosing a test

An HCP may recommend one or more tests, depending on your personal diabetes risk factors; certain tests will likely be followed up with additional tests. How you prepare for each screening will depend on your test, so be sure to follow your HCP’s instructions. Typical test options include:

  • A1C blood test: This gold-standard test measures your average blood sugar levels over the prior three months. An A1C between 5.7 and 6.4 percent indicates prediabetes, while 6.5 percent or higher indicates diabetes.
  • Fasting blood sugar test: This measures your blood sugar level in the morning after not eating all night. A level between 100 and 125 mg/dL indicates prediabetes, while 126 mg/dL or higher indicates diabetes.
  • Glucose tolerance test: This measures your blood sugar level after a night of fasting. You’ll be tested at least twice, however—once before you drink a glucose liquid, and then again from one to three hours afterward. After two hours, a level between 140 and 199 mg/dL indicates prediabetes, while 200 mg/dL or higher indicates diabetes.
  • Random blood sugar test: This measures your blood sugar levels at the time of the test. You can take it anytime, without fasting beforehand. A level of 200 mg/dL or above may indicate diabetes if you also display typical symptoms such as thirst, frequent urination, or blurry vision.

Once you’ve been tested, it’s important that an HCP thoroughly explains the meaning of your results. Be sure to ask questions if any part of the explanation is unclear. Taking notes at the appointment or having someone with you may help you remember information, as well.

Steps to take moving forward

If you test positive for prediabetes, take heart. By making key lifestyle changes like eating a healthy diet, quitting tobacco, and getting enough physical activity, you have the opportunity to get your blood sugar levels under control and perhaps avoid type 2 diabetes.

And if your test indicates type 2 diabetes, these lifestyle changes—along with medications—can help you manage the condition and avoid complications.

Article sources open article sources

Centers for Disease Control and Prevention. Diabetes Fast Facts. Page last reviewed April 4, 2023.
U.S. Preventive Services Task Force. Final Recommendation Statement: Prediabetes and Type 2 Diabetes: Screening. August 24, 2021. 
Centers for Disease Control and Prevention. Diabetes: All About Your A1C. Last reviewed September 30, 2022.
American Diabetes Association. Diagnosis. Accessed November 13, 2023.
National Institute of Diabetes and Digestive and Kidney Diseases. Risk Factors for Diabetes. Page accessed September 13, 2023. 
Centers for Disease Control and Prevention. Diabetes Symptoms. Page last reviewed September 7, 2023. 
Centers for Disease Control and Prevention. Diabetes Tests. Page last reviewed February 28, 2023. 
Centers for Disease Control and Prevention. Prediabetes - Your Chance to Prevent Type 2 Diabetes. Page last reviewed December 30, 2022.
Mayo Clinic. Prediabetes. November 11, 2023.

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