The Hemoglobin A1c (HbA1c) blood test measures glycosylated hemoglobin, indicating your average blood glucose levels over a 90-day period. Hemoglobin carries oxygen through your body using your Red Blood Cells (RBC’s) as its vehicle. As your blood glucose levels rise above normal, sugar combines with the hemoglobin molecules and your blood cells become “glycosylated.”
The average life span of an RBC is 90 days, at which time they are shed from the body via the spleen and new RBC’s are formed. Once the hemoglobin has become glycosylated, it will remain that way for the entirety of its Red Blood Cells life span. Therefore, when your blood is drawn and an HbA1c level is tested for, it will show the average amount of glycosylation in your blood via the hemoglobin molecules. Essentially indicating your average blood glucose level and how well you have been doing in controlling your diabetes over a 3-month period (90 days).
In patients without diabetes, the normal HbA1c level is between 4% and 6%, with an average daily glucose level of 90mg/dL. For the diabetic patient remember: “7 and below is the way to go!” Your Podiatrist and your Primary Care Physician are looking for your A1c level to be below 7%, as that indicates that over a 90-day period your average daily blood glucose level has been around 170 mg/dL. HbA1c testing is a foolproof way for your doctor to gain an accurate picture of your sugar control over a longer period of time than just on the day they see you in their office. Thus, fasting or eating healthier and controlling your sugar levels the day or two before heading to the doctors for your blood test, will not be effective in lowering your HbA1c level. It is a more accurate way of gauging your glucose control and overall control of your diabetes.
The chart below outlines the average blood glucose levels that correspond to your Hemoglobin A1c level. As you climb the chart in your A1c percentage, it shows that your average blood glucose levels are increased over a 90-day period and the risk of complications from diabetes become greatly increased.
HBbA1c Average Blood Glucose Level
12% 345
11% 310
10% 275
9.0% 240
8.0% 205
7.0% 170
6.0% 135
5.0% 100
4.0% 65
The higher your A1c, the more glycosylated your RBC’s become, the more uncontrolled your diabetes has been, and the higher your risk of complications stemming from the disease becomes. Some of those complications include diabetic neuropathy, retinopathy, kidney complications and decreased blood flow to the hands and feet! Control of your blood glucose level is the best tool as a diabetic patient that you have in decreasing your risk of long-term complications, and it is something that once you pay close attention to long enough, maintaining your levels will become second nature. Over the next 3 months I challenge you to control your glucose levels so that on your next HbA1c testing, your “day- of” glucose level will match that of your 90 day average!
As an aside, it is important to remember that Hemoglobin A1c levels are not to be confused with standard blood hemoglobin levels, which indicate your body’s ability to transfer oxygen from the lungs to the tissues, and carbon dioxide from the tissues back to the lungs for expiration.
