What You Need To Know About HbA1c

It’s a term our doctors always talk about, but what is it?

By Susan B. Sloane, BS, RPh, CDE

Anyone with diabetes has most likely had an HbA1c test at some point.  You may not even realize what that is, other than looking at it on your lab values from your blood work report.  This test has been one of the gold standards for measuring how well diabetes is controlled in patients.  The test is generally performed every 3-4 months, and it will be reflective of an average blood glucose over that period of time.

We have already discussed what the HbA1c values correlate to in terms of an average blood glucose as well as the importance of testing blood glucose at home.  Your own health care team will decide what your HbA1c goal should be.  If your HbA1c is over above your target value, and your fasting blood sugars are on point, this means that you probably have higher than normal post-prandial, or after meal blood glucose readings.  The HbA1c can prevent patients from coming to an incorrect conclusion about their diabetes control.  Some people only test blood sugars in the morning after fasting; this doesn’t provide the whole picture as to how well your diabetes is being controlled.

Diabetes treatment is often decided upon by looking at HbA1c values.  For example, according to the newest American Diabetes Association guidelines, an elevated HbA1c in a newly diagnosed type 2 patient indicates that basal insulin should be considered as part of that patient’s treatment.¹

Keep in mind that unlike a few home blood sugar values, the HbA1c test reflects long term glycemic control.  Newly diagnosed patients, for example, that present to the doctor’s office with an HbA1c or 9 or 10 probably have had type 2 diabetes for a long period of time without symptoms.  In contrast, if a patient has an HbA1c test that is very low, it may indicate that that patient has been having frequent low blood sugars.²  It is important to stay in good control, while avoiding excessive hypoglycemia that can also be dangerous.  Staying within the navigational beacons to keep diabetes in control is challenging, but achievable.

As has been stated before, bringing down a clinically elevated HbA1c to an acceptable level can significantly reduce the possibility of diabetes complications.³   In general, your provider will give you an HbA1c test four times a year if you are not at goal, or yearly if you seem to being well.  This is for the type 2 patient, as the patient with type 1 diabetes may need more frequent testing because of their total dependance on insulin therapy.  Below is a conversion chart that may help you understand your HbA1c a little better. ⁴

 Correlation of HbA1c with Estimated Average BG

HbA1c                      mg/dl                      mmol/l

6                                 126                        7.0

7                                 154                        8.6

8                                 183                       10.2

9                                  212                       11.8

10                                240                       13.4