In last week’s blog, we explained the importance of patient self-monitoring of blood glucose (SMBG), and continuous glucose monitoring (CGM) for patients with diabetes. This week, we want to go over the A1C test, goals and recommendations, and the limitations of A1C testing.

What is it?

According to the National Institute of Diabetes and Digestive and Kidney Diseases, the A1C test is a blood test that provides information about a person’s average levels of blood glucose, over the past three months. This test is the primary test used for diabetes management and diabetes research.

What are the advantages?

The advantages of this blood test include: greater convenience for patients, greater pre-analytical stability, and less day-to-day perturbations during stress and illness.

What are the disadvantages?

The disadvantages of this blood test include: lower sensitivity of A1C at the designated time of testing, greater cost, limited availability of A1C testing, and the lack of correlation between A1C and average glucose in certain patients.

What are the goals and recommendations?

Recommendations are as follows:

• Testing should be considered in adults at any age who are overweight.
• For those not overweight, testing should begin at 45 years old.
• If tests are normal, repeat testing at three-year minimum intervals.
• Testing for pre-diabetes should be considered in children and young adults who are overweight and have two or more additional risk factors for diabetes.

According to the Standards of Medical Care in Diabetes, when using A1C testing, it is important to recognize that A1C is an indirect measure of average blood glucose levels and to take other factors into consideration. Unless there is a clear diagnosis, a second test is required for confirmation.