What is the benefit of a fasting blood test for a known diabetic in routine annual checks against a non fasting blood test?

QUESTION: What is the benefit of a fasting blood test for a known diabetic in routine annual checks against a non fasting blood test?


My opinion is that surley the results will be skewed and not an indication of every day living. I ask this question as at one medical practice I was with, they did not perform fasting blood tests, which I think is sensible, my current medical practice insist on a fasting blood tests.

I have an inherent distrust of doctors and nurses most of them are to full of their own self importance.


ANSWER: Hi there,

You have to know that there exist several tests, which are providing information about the control of your blood glucose level. Generally, they can be divided in two groups - fasting and non-fasting blood glucose tests, like you said.

Both groups are having advantages and shortcomings and for that reason you need to run them accordingly or/and at the same time.

In the following, I will try to explain some basic things related with those tests:

1. First, the fasting blood glucose test represents the amount of glucose when you are hungry. This test is important, because it provides information about the ability of the organism to handle with the glucose elevation in long period around 8-10 hours.

This is an easy and cheap test as compared to the non-fasting blood glucose tests. However, it can’t provide information about the short-term control of the blood glucose, which is also important.

2. Second, regarding the non-fasting blood glucose tests, there are two options - random blood glucose test and oral glucose tolerance test.

During the random blood glucose test, you have to inform your doctor when was the last time you eat something and what was it. Then, a blood sample is taken. This test shows occasional value of your blood glucose, which is important for non-diabetic person, or for a person with not confirmed diabetes.

During the oral glucose tolerance test, you have to drink a glass with 75 mg of glucose. Then a blood sample is taken 4-5 times during the next 2 hours. This test provides information about the short-term control of the blood glucose concentration. This test is generally used on patients with not confirmed diabetes, or on patients who are suspected for progressive diabetes, like diabetes type 2.

  • You are right in two things - generally, the fasting blood glucose test along with the HbA1c test, is used on patients with confirmed diabetes and those tests are not representing your lifestyle.

    The only test representing your lifestyle is the HbA1c test, which shows the control of your blood glucose during the last 2-3 months. However, I’m not aware of your present general condition and the other things related with your diabetes.

    I can only suppose that your doctors were suspecting something, which you don’t know and for that reason they have executed non-fasting blood glucose test.

    Hope it helped! All the best!

    Dr.Alba

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