Is a fasting glucose test good enough to understand your pre-diabetes/diabetes risk?

ASK YOUR DOCTOR ABOUT AN A1c TEST AS A BETTER INDICATOR OF YOUR PRE-DIABETES AND DIABETES RISK.

Most of us have had a fasting glucose test. It is usually done as part of the standard blood work at annual check ups. It is usually this lab result that triggers the doctor to tell you that your blood sugar is “a little high” or “just fine”. The problem is that a fasting glucose test is really not an accurate indicator of your blood sugar status. It certainly is an easy test to do, since it uses blood from the blood drawn at your physical. But it is easily misleading.

Some reasons are as follows: If you had a low sugar or low carbohydrate (think steak and veggies) early dinner the night before, the number could actually be artificially low. If you had a high sugar and or a high carb dinner (think spagetti with ice cream for desert) late in the evening, the number could be artificially high. The reason I say “artificially” is because a fasting glucose test measures serum sugar, and that can fluctuate morning to morning.

There are other test that can be done to measure how insulin resistant or insulin sensitive you are but they are prolonged and can be painful as they require multiple blood draws (like the OGTT-Oral glucose tolerance test) or are costly or both. However, if you really want a much better indicator of your blood sugar status, ask for the hemoglobin A1c test. It is highly respected, more telling and easily done with the blood taken at your physical.

Why? Here is how the Mayo clinic stated it in on Dec. 1st, 2022. (Mayoclinic.org/about). “The A1c test results reflect your average blood sugar level for the past two to three months. Specifically, the A1c test measures what percentage of hemoglobin proteins in your blood are coated with sugar.”

The more sugar the hemoglobin in the red blood is carrying, the less oxygen they can carry. This sugar load is expressed as a percentage, and the higher that number is, the worse your blood sugar issue, and risk of diabetes, becomes. Since red blood cells survive in your blood for a about 90 days, examining them in an A1c test, allows your doctor to access how your sugar control and insulin sensitivity has been over a long period of time (about 3 months) vs just over one night like the fasting glucose test.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, a “normal” A1c level is 5.6% or lower. However, his number is not a line in the sand. Its not like you’re instantly in trouble at 5.7% or instantly out of trouble if you are 5.6%. Most experts will agree that the lower you are in percentage the better off you are and the higher you are, the worse off you are. Your doctor might suggest, that if you are slightly above 5.6% then take action to get it lower and if you are slightly below 5.6% take action to try to get it even lower.

My blood sugar climbs whenever I go for any period of time at all with poor or too little sleep. So, I have my A1c checked 3 times a year to make sure it is does not trend up on me by surprise. If you can afford a CGM (Continuous glucose monitor) by all means get one. It is by far the best way to know exactly how you are doing at managing your blood sugar. By the way, insurance companies are used to paying for the A1c test, but not so good at paying for a CGM device unless you are at least pre-diabetic already. It is not uncommon to have the A1c test done and if it is over 5.6% then be able to get a CGM covered.