What The A1C Test Can Tell You

What The A1C Test Can Tell You

The essence of diabetes management is using an individualized combination of diet, exercise, medications, and occasionally stress management to keep blood glucose within a safe physiological range. The managing health professional helps the patient establish a range of fasting target values; for an individual without diabetes, this range is 70-100 mg/dL (3.9-5.6 mmol/L). However, perhaps even more useful is information about how well blood glucose is being managed over the last few months, because knowing this makes possible adjustments to the care plan and alerts the care provider to the risk of complications.

What is the hemoglobin A1c test?

It is a normal process for blood glucose to adhere to proteins. In particular, glucose readily adheres to β-chains in hemoglobin, the molecule that carries oxygen to all the cells of your body, forming “glycated hemoglobin.” Once a glucose molecule binds hemoglobin, it’s there to stay for the lifetime (about 120 days) of the red blood cell containing the hemoglobin (RBC). Hemoglobin A1c tests give a weighted average of the percent of glycated hemoglobin; recent increases in glycosylation influence A1c readings more than those occurring several weeks before.

As a result, the test provides a useful measure of how well blood glucose has been managed over a period of two to three months prior to the test. Used in conjunction with glucometer readings, A1c results can alert care providers to changes in the status of patients and help them adjust medications and make specific lifestyle recommendations.

Because the A1c is not a fasted glucose test, it generally gives somewhat higher readings. For people without diabetes, it is normal for 4.1%-5.6% of hemoglobin to be glycated; a 5% reading corresponds to 97 mg/dL.[1,2] If your initial A1c test returned a 5.7%-6.4% reading, your doctor would conclude that you were pre-diabetic and suggest appropriate dietary and lifestyle interventions — low-GL diet and carb counting, combined with resistance training and aerobic exercise — to help you lose weight and improve insulin sensitivity. Because of the difficulty encountered in helping diabetic patients return to the normal range, care providers often establish a higher-than-normal standard, say 7% glycated hemoglobin, as acceptable for patients.

Can specific interventions move A1c readings down significantly?

Several lifestyle changes can help optimize A1c readings. Research suggests that combining resistance training with appropriate cardiovascular exercise has a greater effect on improving A1c status than programs without resistance training.[3] Resistance training has additional benefits because it enhances glucose uptake by muscle during exercise recovery. Resistance training also over time increases the amount of muscle tissue.

However, care must always be taken in interpreting A1c readings. Because the percent glycated hemoglobin is an average of the extent to which hemoglobin binds glucose during the day, and larger amounts of glucose enhance that process, elevated A1c readings suggest that for inappropriately long periods on most (or all) days, the body is not responding to fluctuations in blood glucose in a healthy manner.

An elevated A1c reading is common in cases of insulin resistance, which in turn has been linked to obesity and chronic inflammation. As a result, doctors have increasingly valued continuous monitoring of blood glucose throughout the day to understand more directly the relationship between diet, lifestyle, and insulin efficacy.

When taken in combination with continuous monitoring, a hemoglobin A1c test every three months provides a window into the central challenge of diabetes and makes managed care far better. Knowledge is power.

[1] http://www.webmd.com/diabetes/guide/glycated-hemoglobin-test-hba1c

[2] http://www.mayoclinic.org/tests-procedures/a1c-test/details/results/rsc-20167939