Fasting Blood Sugar: What You Ought To Know

Also known as Fasting Blood Sugar, Fasting Glucose Level.

Fasting blood glucose measures the amount of glucose (a type of sugar) in a person’s blood.

It is used to screen for diabetes and can be used to make a diagnosis when symptoms of diabetes like excessive thirst, excessive hunger, frequent urination and unexplained weight loss are also present.

How is Fasting Blood Glucose Tested?

The test checks for glucose levels in the blood when a person has not eaten.

It is required that at least eight (8) hours before the test, a patient should not have eaten or consumed any form of food or drink (alcohol, juice or carbonated) – water is fine though.

Blood samples are required to test for this test. The blood samples may be drawn from a vein or pricked out of the finger, a drop or couple of them is sufficient to get results.


When is an FBS Test Needed?

Symptoms of hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar) can necessitate testing for fasting blood sugar.

Both are symptoms that are suggestive of diabetes. Both high and low blood sugar may cause a person to witness heart palpitation, tiredness or weakness, dizziness and anxiety. In some cases of hyperglycemia, joint aches are a symptom.

When a person begins to exhibit these symptoms, a glucose check is required. Similarly, diabetic patients and pregnant women are usually required to take the Fasting blood sugar test often to keep track of blood sugar levels over a period of time.

What is Checked in Fasting Blood Sugar Test?

The human body sources energy from the food it consumes.

Glucose, usually the final by-product of carbohydrates among other types of sugar in the body, is the major source of energy for the body.

The small intestine is responsible for absorbing this glucose and circulating it across the body for energy distribution.

Even the brain and nervous system rely on glucose to function optimally and would only do so with blood sugar level at best readings – not over and definitely not under.

The pancreas is responsible for the secretion of insulin, an essential hormone that bolsters/controls the transportation of glucose to the cells for energy generation.

It is also responsible for the liver’s temporary storage of glucose as glycogen as a short term energy reserve. Insulin also handles the synthesis of fats from glucose.

How well the body uses glucose depends on insulin production in the body. Thus, a balanced level of insulin and glucose is necessary for healthy living. When the glucose in the body is high, the pancreas releases insulin to lower it.

In times when the blood sugar is low, glucagon, another hormone also secreted from the pancreas triggers the liver to release the glycogen temporarily stored.

This is because, at every point in time, the level of glucose in the blood must be corresponding to the level of insulin available.

When glucose is higher, it points to a possibility that insulin resistance is high in the body system; when it’s low, it translates to insulin levels being higher than the glucose in the blood – both of which are pointers to diabetes.

Both ways, hyperglycemia and hypoglycemia can be indicators of life-threatening conditions including organ damage.

Hyperglycemia during pregnancy otherwise known as gestational diabetes can have adverse effects on a foetus/baby including preeclampsia – a pregnancy complication characterised by high blood pressure, swollen feet and/or ankles, and the presence of protein in the urine.

Other common consequences attributed to untreated high blood sugar and insulin resistance include damage to nerves, blood vessels, eyes, and heart as well as obesity.


How is The Test Used?

The test is called fasting blood sugar because a fast is required before the test is taken. This fast is suggested by medical professionals to be at least eight (8) hours prior to the test.

This is to ensure that results are influenced by the impact of food, drink or alcohol consumed within the cycle of time the test is conducted.

It also fosters a much more accurate output than other forms of glucose tests like the Oral Glucose Tolerance Test.

For pregnant women, glucose levels should be checked in the 24th and 28th weeks of pregnancy to avoid risks of gestational diabetes.

Patients with diabetes should check their sugar levels regularly to keep track of their health and also stay informed on the types of diet and medications they must keep up with.

What is a Fasting Blood Sugar Result Like?

The values used in determining the results of an FBS are broken down below:

  • Normal and healthy is 70 – 100mg/dL
  • Prediabetes or Impaired Fasting Glucose is 110 -125mg/dL
  • Diabetes and unhealthy is 126 mg/dL


What Does the FBS Results Range Mean?

With results that fall within the range of 70 – 100mg/dL, blood sugar is considered balanced and healthy without worry of insulin resistance, diabetes or risk of it.

On a range between 110 and 125 mg/dL, blood glucose is pegged at prediabetic.

What this means is that the blood glucose is high and abnormal, although still a bit safe from diabetes.

A patient with such a reading is often advised to cut down on sugar intakes including watching the intake of soda and sugary beverages as well as regulating the consumption of carbohydrates in healthy calories.

Results with a range of 126 mg/dL or higher are considered diabetic.

Most times, to be sure, doctors recommend a retest in this category and may even try out other forms of glucose level tests to confirm diabetes.

When this is discovered, an entire metabolic assessment and lifestyle check is advised and treatment is to begin immediately.


Like many other glucose tests, the fasting blood sugar test is one effective way to check for glucose levels in a person.

Its results are largely more accurate and they come as a strong pointer for doctors trying to confirm diabetes or risks of or other medical concerns.

It is advised that the FBS test be taken early in the morning before breakfast.

It is much more convenient and accurate at this time given that the last meal consumed was the night prior.


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