Home A to Z Test What Does Fasting Blood Sugar Test Tell You?

What Does Fasting Blood Sugar Test Tell You?

Verified By Apollo Diabetologist September 25, 2020 25660 0

The fasting blood glucose test is mostly performed after you wake up in the morning. This is done so that you do not have to fast throughout the day. It requires you to fast eight hours prior to you taking the test, and it measures your glucose level after the fasting.

Your fasting blood sugar/ glucose levels depend on the following factors:

  • What have you had for your last meal?
  • What was the size of your last meal?
  • What is your body’s ability to produce and respond to insulin?

Blood sugar and insulin – An overview

The carbohydrates that you consume are broken down by your body. This process produces glucose (which is a kind of sugar). The primary energy source for the cells is this glucose. The cells in your liver, muscles, and fats (adipose tissue) use this glucose as an energy source to function correctly. This is possible because of insulin. The excess glucose that is not used up by your body for energy is converted and deposited as fats. These fats can give you energy whenever you have low glucose levels.

The insulin has two main functions. The first is to allow the cells to use the generated glucose generated as an energy source. The second is to make sure that normal levels of glucose are maintained in your bloodstream.

What does your fasting blood sugar test tell about your health?

The doctor will ask you to take a fasting blood sugar test if they believe that you have diabetes. This test can be taken at home, a pathology lab, or at a hospital.

The people who have diabetes have trouble generating insulin, or in terms of how insulin works, or both together. Diabetes is mainly of two types – type 1 diabetes and type 2 diabetes.

Your body is unable to move the glucose to the cells from the blood if the level of insulin in your body is too low or when the body does not react correctly to insulin. This causes high levels of glucose in the blood.

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How much sugar is high blood sugar?

Here are the results of the fasting blood sugar test that determine whether you have diabetes or not:

A blood sugar level less than 100 mg/dL or 5.6 mmol/L rules out the chances of diabetes. It is the normal blood sugar level.
If your fasting blood sugar level ranges between 100 and 125 mg/dL or 5.6 and 6.9 mmol/L, it indicates a prediabetic condition. It is slightly above the normal level of sugar.
A blood sugar glucose of 126 mg/dL or 7.0 mmol/L or more after taking the test twice indicates that you have diabetes.

What happens when you have diabetes?

A high fasting blood sugar level indicates that you have diabetes. It means that you are more likely to have issues with insulin production. It can happen in either of the two ways:

If you are a type 1 diabetic, your body fails to produce a sufficient quantity of insulin. It is because when you have this condition, your body tends to attack the cells that produce insulin.
If you have type 2 diabetes, your body fails to correctly respond to insulin as it should.

How is diabetes diagnosed?

Signs and symptoms of diabetes are sometimes not clear or may appear slowly. Therefore, the ADA (American Diabetes Association) has set some rules for screening this condition. The set of guidelines suggest that the people with the following attributes should take the blood glucose test:

What other tests will your doctor recommend to diagnose type 1 and type 2 diabetes and prediabetes?

Glycosylated hemoglobin test: It is also known as the Hemoglobin A1c test. This test does not need you to be on an empty stomach. It evaluates your average blood glucose level over two to three months by measuring the blood glucose portion attached to hemoglobin. If your blood sugar levels are high, the percentage of sugar-attached hemoglobin will also be high. Here are some pointers for your reference:

  • If your A1c level is 6.5% or more after performing the test twice, it indicates diabetes.
  • If it ranges between 5.7% and 6.4%, you are most likely to be prediabetic.
  • If it is less than 5.7%, you have a normal level of sugar in your body.

Random and Postprandial (two hours after a meal) glucose measurements may also be taken.

Why is self-monitoring crucial for a diabetes patient?

If you have diabetes, self-monitoring of the condition can help you manage your blood glucose level and prevent complications. You can check if you have a normal blood sugar level with the help of a blood sugar meter, which is a compact electronic tool . It is easy to use and accurate. All you have to do is put a small drop of blood on the disposable strip, wait for a few seconds, and you instantly get your results. You can use it to check both fasting and random blood sugar levels.

Frequently asked questions (FAQs)

Can I drink water before taking a fasting blood sugar test?
You can drink only water, no other drinks or food before your fasting blood sugar test.

Why is my fasting glucose high in the morning?
If your fasting blood glucose is as high as 126 mg/dL or 7.0 mmol/L or more, you should get in touch with a doctor as you might have diabetes.

What is the normal blood sugar level after fasting for 12 hours?
The normal blood sugar level after fasting for 12 hours is less than 100 mg/dL or 5.6 mmol/L.

Does caffeine affect blood sugar?
Studies say that consuming 400 mg of caffeine in a day does not create a problem for most people. A few studies propose that consuming coffee might actually reduce a person’s risk of contracting type 2 diabetes. Though if you are already diabetic, the effect of coffee (caffeine) on insulin might be related to low or high blood sugar levels. This effect varies from person to person. Therefore, people who have diabetes are suggested to have only a certain amount of caffeine (not overdo it) and limit their consumption.

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