What to know about fasting blood sugar?

Last updated on September 26th, 2022

When you have diabetes, your blood sugar level can remain consistently high over some time. If you ignore diabetes control on time then it can cause damage to different organs of your body and affects your health. Therefore, it is important to get your blood sugar level checked regularly. When you go for a blood sugar test, you will come across the terms fasting blood sugar test and PP sugar test. Both the test has its own significance in your diabetes reversal.

What is a fasting test for blood sugar?

The fasting plasma glucose (FPG) test, also known as the fasting blood glucose test (FBG) measures the levels of glucose (sugar) in the blood in the fasting state (empty stomach). It is the most commonly prescribed test for people with diabetes or suspects who have symptoms of diabetes.

It is advised not to drink or eat anything at least for 8-12 hours before the test. It will help you to get the accurate results of your fasting sugar test.

fasting test for blood sugar

Significance of Fasting diabetes test

Post-fasting sugar level is always high. When you eat something, the blood glucose levels rise immediately to higher levels and go down after some time. It happens because when you eat something (carbs), carbohydrates get broken down into a simpler substances called glucose (sugar). Those sugars enter the mainstream of your blood and increase blood sugar levels. At the same time, your body releases insulin which prompts the cells to absorb sugar from your blood.

Fasting triggers the production of a hormone, Glucagon that increases the body’s glucose levels. If a person is non-diabetic, his/her body will produce Insulin which will rebalance the blood glucose levels. However, a person with diabetes will not produce enough insulin or able to use insulin effectively. As a result, blood glucose levels will not get rebalanced. Consequently, the blood sugar levels will be higher in a person with diabetes than a non-diabetic person.

The purpose of the fasting glucose test is to know how your body is maintaining sugar levels. Blood sugar levels between the meals provide a picture of how your body manager the sugar levels. If a person is either type-1 or type-2 diabetic, then his/her body will not produce or use insulin. Thus, it is easier to know if the person is diabetic or prone to diabetes.

Normal range of fasting blood sugar

Normal range of FBS

The normal fasting blood sugar range is not the same for everyone. People with no diabetes, prediabetes, or diabetes have a different normal range for fasting blood sugar. You should know your normal range when you go for the fasting plasma glucose test. It will help you and your doctor to understand whether you are required to control your sugar levels or your body is responding fine to Insulin production.

The results of a normal fasting blood sugar test concerning your body glucose levels are as follows:

  • Normal adults: The fasting blood sugar normal range for normal adults while fasting or before breakfast is 60-90 mg/dL. It means that your pancreas is properly secreting insulin and your body is effectively responding to its functionality. However, your blood test reading depends upon what you ate last.
  • Pre-diabetes or Impaired Glucose Tolerance: If you are prediabetic then your normal blood glucose level while fasting will be 100-125 mg/dL. Getting the blood sugar test results on a bit higher side doesn’t mean that you will automatically develop type-2 diabetes. Instead, you need to take some precautions to control your blood sugar levels. Pre-diabetes is a reversible condition.
  • People with diabetes: The normal fasting diabetes range for people with either type-1 or type-2 diabetes is 126 mg/dL or higher. In this case, your doctor will diagnose you with type-1 or type-2 diabetes, and accordingly, you will be advised for regular blood glucose monitoring, medications, supplements, and lifestyle changes.
  • If your fasting plasma glucose levels are on the borderline or indicate that you have diabetes then you will need to repeat this test in the future to monitor your blood glucose levels. There are few other tests including postprandial plasma (pp) sugar test, hemoglobin A1c test, or oral glucose tolerance test, which are done along with fasting sugar test. You should have a open dialogue with your doctor regarding the readings of your FBG test to know the next step you need to take.

Risks with low fasting blood test results

If your results of blood test for normal sugar level before fasting is in the normal range then you don’t need to worry as you are on the safer side. However, you may have low blood sugar or hypoglycemia if your FBG reading is below 55mg/dL. Low blood sugars can develop conditions like pancreatic tumors, malabsorption syndrome, or liver and kidney inefficiency. Apart from these severe health issues you will also feel weakness, fatigue, irritated, sweaty and nauseous.

Preparation for the fasting diabetes test

If you are going for the fasting blood sugar level test, you must ask your doctor about the fasting blood sugar test preparation and follow the instructions. It will help you to get accurate results of your blood sugar level. You are recommended not to eat or drink anything for some hours or overnight before you take this test. Generally, it requires fasting of around 8-10 hours therefore many people prefer to get this test done early in the morning.

Apart from fasting correctly, there is no other special preparation required if you are going for the fasting test for diabetes.

Also Read: How to Lower Blood Sugar?

Tips to follow to take fasting blood test

There are few things to remember if you are going for the fasting blood test for diabetes. These include:

  • Keep drinking water to stay hydrated. Water does not affect the test results because it does not contain carbs that broke down into sugar. Therefore, it is acceptable if you are drinking water.
  • It is essential to keep in mind the timings when you can eat or drink before the test. You are supposed to fast for at least 8 hours for a fasting blood test. If you have taken your last meal at 10:00 PM then you should go for the test at around 6:00 AM.
  • You should not skip your regular medication for fasting glucose tests. You can take your medicines unless your doctor has told you to avoid them.
  • Fasting is safe for pregnant women. Still, you can ask your doctor about fasting before the test and get proper advice to get your blood test done safely.

Sample collection for FBG test

Sample collection for FBG test
Doctor checking blood sugar level with glucometer.

The health care provider at pathology firstly cleans the area with an antiseptic lotion before drawing your blood. An elastic band is then tied on your upper arm that swollen your veins with blood. Once, the health care provider who is collecting the sample finds your vein he/she will insert a clean needle into your vein. With the help of a syringe, he/she will draw your blood and collect it in an air-tight glass bottle.

When the needle goes in, you may feel moderate pain but it will subside within few minutes as soon as you relax your arm. The health care provider will also put a sterile bandage at the punctured site to avoid bruising.

If you are taking a diabetes fasting blood sugar test at home with the help of a glucometer, you are required to prick your finger to let a drop of blood come out. A drop of blood is then put on the testing strip, which is inserted into the machine to get the fasting blood glucose results.

Cost of blood glucose test

The cost of fasting and pp blood sugar test is very nominal. On average, the cost of a fasting diabetes test is around Rs 50 while the average cost of pp blood sugar test is Rs 150. There are diabetes test kits available in the market if you want to get your blood glucose test done at home. You can invest one time in such type of testing kit and monitor your fasting and post-meal glucose level at home. The average starting price of such kits is Rs 1000, including the price of testing strips. Blood sugar test strips are also available separately at an average cost of Rs 500 for 50 strips.


Can I book the fasting blood glucose levels test online?

Yes, these days lot of pathology labs are providing online booking for the fasting diabetes test. You can choose the pathology where you want to get your test done. Choose the fasting test for diabetes from its online portal. Schedule your sample collection time and make the payment. The pathologist will come to your place at the scheduled time and collect your sample safely. This method of blood test is convenient and saves time as well.

What to do if your fasting glucose levels are higher?

If you have never got your blood sugar levels checked earlier but your fasting glucose test report shows that your blood sugar levels are higher than the fasting blood sugar normal range then you should immediately consult your doctor. Right medications and timely diabetes management help in maintaining your health.

How long does it take to get the test report?

If you are getting your fasting blood glucose levels checked at home with the help of a glucometer then you can get the results within few seconds. If you want a Fasting blood test done at pathology then it may take around 24-hours to interpret the results.

Are there any risks in taking a test for fasting blood sugar?

A fasting blood test for diabetes is a simple test. No severe risks are there in taking this test. However, some people experience pain at the puncture site. There can be bleeding also but for some time which may last few minutes.

Who can go for the fasting blood test done?

Anyone who wants to monitor his/her blood sugar level or advised by the doctor after experiencing symptoms of low or high blood sugar can go for this test.




Last Updated on by Dr. Damanjit Duggal 


The information included at this site is for educational purposes only and is not intended to be a substitute for medical treatment by a healthcare professional. Because of unique individual needs, the reader should consult their physician to determine the appropriateness of the information for the reader’s situation.

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