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MedlinePlus is a service of the National Library of Medicine (NLM), the world's largest medical library, which is part of the National Institutes of Health (NIH). It was built as an online health information resource for patients and their families and friends.

MedlinePlus presents high-quality, easy to understand, relevant health and wellness information that is trusted.

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MedlinePlus at a Glance

  • Offers information on health topics, human genetics, medical tests, medications, dietary supplements, and healthy recipes.
  • Sourced from more than 1,600 selected organizations.
  • Provides 40,000 links to authoritative health information in English and 18,000 links to information in Spanish.
  • In 2018, 277 million users viewed MedlinePlus more than 700 million times.

A1C

A1C is a blood test for type 2 diabetes and prediabetes. It measures your average blood glucose, or blood sugar, level over the past 3 months. Doctors may use the A1C alone or in combination with other diabetes tests to make a diagnosis. They also use the A1C to see how well you are managing your diabetes. This test is different from the blood sugar checks that people with diabetes do every day.

Your A1C test result is given in percentages. The higher the percentage, the higher your blood sugar levels have been:

  • A normal A1C level is below 5.7%
  • Prediabetes is between 5.7 to 6.4%. Having prediabetes is a risk factor for getting type 2 diabetes. People with prediabetes may need retests every year.
  • Type 2 diabetes is above 6.5%
  • If you have diabetes, you should have the A1C test at least twice a year. The A1C goal for many people with diabetes is below 7. It may be different for you. Ask what your goal should be. If your A1C result is too high, you may need to change your diabetes care plan.

NIH: National Institute of Diabetes and Digestive and Kidney Diseases