Fasting Blood Sugar Level: Normal levels & testing

If you are worried about getting your diabetes or prediabetes checkups,  we are here to tell you everything you need to know about the easily performed and commonly preferred fasting blood sugar tests prescribed. This test helps detect conditions, such as diabetes, prediabetes, or gestational diabetes. 

Diabetes is a condition wherein the circulating glucose/ sugar levels are present in higher amounts in the blood. A fasting blood sugar test is a simple and safe routine blood test done after a minimum of 8 hours of overnight fasting that analyses the blood sugar levels when it needs to be below.

This article gives you an insight into the fasting blood sugar levels while discussing all the details of the fasting blood sugar test, its importance, and more. 

Fasting Blood Sugar Test: What is it?

Fasting blood sugar test, also known as the fasting blood glucose analysis, a fasting blood sugar test is a simple blood test done to diagnose conditions such as diabetes, prediabetes, and gestational diabetes. As the name suggests, the test is usually done after a fasting period of at least 8 hours. 

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Typically, after overnight fasting, where the person undertaking the test must-have meals in the night with no solid and liquid except water taken in between. The blood sample is drawn the next morning before the next meal. 

How to understand who is eligible for the test?

Type 2 diabetes or prediabetes conditions often go unnoticed as most of the time the symptoms can get difficult to identify and narrow down as diabetic. Physicians may order a fasting blood glucose test if a person feels lethargic, gets tired even after a regular activity, or has a slow healing wound. The other circumstances for taking this test include:

• It is usually a part of the routine full-body check-up.
• People above 35 are required to take this test annually.
• Pregnant women may be suggested this test check for gestational diabetes- diabetes during pregnancy. 
• A person having symptoms of diabetes
• A person with a family history of diabetes
• A person with a previous history of high glucose levels.

Why do you need the test?

Glucose, a form of sugar found in the blood, is a byproduct of complex carbohydrate breakdown and is mainly obtained from food or drinks. 

The hormone insulin produced by the pancreas allows the cells to absorb blood sugar for their activities and energy conversion necessary for their daily activities. As the cells use up the blood sugars, the blood sugar levels and insulin production lowers. But, when the blood sugar levels rise, the pancreas pumps up more insulin. 

But, in a condition like diabetes, the body has problems regulating blood glucose. Either the pancreas does not make enough insulin, or the cells do not process insulin effectively. Hence, the glucose in the blood is not effectively used up by the cells, causing a rise in blood sugar levels. And excess glucose levels in the body can damage the organs and their functioning. 

A fasting blood sugar test measures the sugar levels in the blood when it needs to be at their lowest levels. During an early morning or post fasting blood sugar test, the body’s cells would have used up most of the blood glucose and must indicate low sugar levels. 

How is the test done?

Before the fasting blood glucose test, your physician will advise you to observe an overnight fast of a minimum of 8-12 hours and then take the test in the early morning. You will need to take your meal the night before, after which there must be no solid or fluid intake except for water. 

During the test, the lab technician will draw a required amount of blood from the veins of the arms by pricking and inserting a needle. The lab technician can collect the test samples at home, at the diagnostic centre, or the hospital.  

After the blood withdrawal, the lab technician will process the blood sample and give you the results the same day or within 24 hours of the test. 

Interpretation of fasting blood sugar test results

The reference ranges of blood glucose levels are indicated in milligrams per decilitre. The glucose range values and their interpretations are mentioned below.

Fasting Glucose levels	Indications
99 mg/dL or lower	Normal Fasting Blood Sugar level
100-125 mg/dL	This range of fasting blood glucose levels is higher than normal but cannot be classified as diabetes- indicating prediabetes.
126 mg/dL or above	Higher than normal fasting sugar level - indicating diabetes or insulin resistance

If your results show a high fasting blood sugar level, your physician may recommend a re-test or additional tests such as a random/ non-fasting blood sugar test, A1c test, and oral glucose tolerance test. 

Even if the test reports show a prediabetic condition, a repetition of fasting blood sugar levels for a couple of years will help the doctor understand the condition's progress towards type 2 diabetes. 

Abnormally lower than normal glucose values indicate hypoglycemia (low blood glucose) or can be due to diabetes medications. This is a life-threatening condition.

Conclusion

With no risks or complications, a fasting blood sugar test is a diabetes monitoring test that detects if a person has diabetes, prediabetes, or gestational diabetes. Before the test, refrain from eating or drinking anything except for water. Connect with your physician if you have symptoms of diabetes or need a full-body checkup done. Your doctor will guide you to get a fasting blood glucose test. 

Frequently Asked Questions

• What should be my blood sugar while fasting?

According to the World Health Organisation (W.H.O), the expected values for normal fasting blood glucose levels are anywhere between 70 mg/dL (3.9 mmol/L) and 100 mg/dL (5.6 mmol/L). When fasting blood glucose levels increase from their baseline level to 100 to 125 mg/dL (5.6 to 6.9 mmol/L), changes in lifestyle, diet, and regular glucose monitoring are highly recommended.

•  Can we drink water before the fasting sugar test?

Fasting sugar testing is an easy and simple blood test done after an 8 to 12-hour overnight fast. Though the test recommends no food and fluids, water is an exception and can be taken before the test and during fasting period.

• Is fasting blood sugar 119 high?

The fasting blood glucose level below 100 mg/dl is considered normal. A person with a prediabetic condition will have a fasting blood sugar level between 100 and 125 mg/dl. And if your fasting blood sugar level is 119 mg/dl, it indicates a prediabetic condition. And will require repeat fasting blood glucose tests a couple of times for two to three years to analyze the progression toward type 2 diabetes.