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Testing blood sugars

A1C, also called HgA1C, is a blood test that helps understand the amount of blood glucose on an average in the past 2-3 months.

Blood sugar test

Checking blood sugar, also called blood glucose, is an important part of diabetes care. The blood sugar numbers show how well the diabetes is managed. And managing the diabetes means that there will less chance of having serious health problems, such as kidney disease and vision loss or even blindness.

2-3 month average

  • The A1C (A-one-C) is a test done in a lab or at your healthcare provider’s office. This test provides an average blood sugar level over the past 2 to 3 months.

Target blood sugar

Target blood sugar levels in people with diabetes:

  • Right before your meal: 80 to 130
  • Two hours after the start of the meal: Below 180.


High blood sugar is also called hyperglycemia (pronounced hye-per-gly-see-mee-uh) which means the blood sugar level is higher than the target level or over 180.


Low blood sugar is also called hypoglycemia (pronounced hye-poh-gly-see-mee-uh) which means the blood sugar level drops below 70. Having low blood sugar is dangerous and needs to be treated right away. Anyone with diabetes can have low blood sugar. You have a greater chance of having low blood sugar if you take insulin or certain pills for diabetes.

Treating low blood sugars

Carrying supplies for treating low blood sugar can help. Symptoms of low blood sugar including feeling shaky, sweaty, or very hungry.

If the glucometer shows that your blood sugar is lower than 70, one should do one of the following things right away:

  • chew 4 glucose tablets
  • drink 4 ounces of fruit juice
  • drink 4 ounces of regular soda, not diet soda or
  • chew 4 pieces of hard candy

After taking one of these treatments, wait for 15 minutes, then check the blood sugar again. Repeat these steps until your blood sugar is 70 or above. After your blood sugar gets back up to 70 or more, eat a snack if your next meal is 1 hour or more away.

A1C results and what the numbers mean

*Any test used to diagnose diabetes requires confirmation with a second measurement, unless there are clear symptoms of diabetes.
Diagnosis A1C Level
Normal below 5.7 percent
Prediabetes 5.7 to 6.4 percent
Diabetes 6.5 percent or above

Using A1C for diagnosis

When using the A1C test for diagnosis, your doctor will send your blood sample taken from a vein to a lab that uses an NGSP-certified method. The NGSP , formerly called the National Glycohemoglobin Standardization Program, certifies that makers of A1C tests provide results that are consistent and comparable with those used in the Diabetes Control and Complications Trial.

Blood samples analyzed in a doctor’s office or clinic, known as point-of-care tests, should not be used for diagnosis.

The A1C test should not be used to diagnose type 1 diabetes, gestational diabetes, or cystic fibrosis -related diabetes. The A1C test may give false results in people with certain conditions.

Having prediabetes is a risk factor for developing type 2 diabetes. Within the prediabetes A1C range of 5.7 to 6.4 percent, the higher the A1C, the greater the risk of diabetes.

The A1C test used during pregnancy

Health care professionals may use the A1C test early in pregnancy to see if a woman with risk factors had undiagnosed diabetes before becoming pregnant. Since the A1C test reflects your average blood glucose levels over the past 3 months, testing early in pregnancy may include values reflecting time before you were pregnant. The glucose challenge test or the oral glucose tolerance test (OGTT) are used.

Blood glucose tests to diagnose type 2 diabetes and prediabetes

Health care professionals also use the fasting plasma glucose (FPG) test and the OGTT to diagnose type 2 diabetes and prediabetes. For these blood glucose tests used to diagnose diabetes, you must fast at least 8 hours before you have your blood drawn. If you have symptoms of diabetes, your doctor may use the random plasma glucose test, which doesn’t require fasting. In some cases, health care professionals use the A1C test to help confirm the results of another blood glucose test.

Factors affecting A1C test

Conditions that change the life span of red blood cells, such as recent blood loss, sickle cell disease , erythropoietin treatment, hemodialysis, or transfusion, can change A1C levels.

A falsely high A1C result can occur in people who are very low in iron; for example, those with iron-deficiency anemia . Other causes of false A1C results include kidney failure or liver disease.

If you’re of African, Mediterranean, or Southeast Asian descent or have family members with sickle cell anemia or a thalassemia , an A1C test can be unreliable for diagnosing or monitoring diabetes and prediabetes. People in these groups may have a different type of hemoglobin, known as a hemoglobin variant, which can interfere with some A1C tests. Most people with a hemoglobin variant have no symptoms and may not know that they carry this type of hemoglobin. Health care professionals may suspect interference—a falsely high or low result—when your A1C and blood glucose test results don’t match.

Not all A1C tests are unreliable for people with a hemoglobin variant. People with false results from one type of A1C test may need a different type of A1C test to measure their average blood glucose level.

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