Fasting Blood Sugar (FBS) Test: Normal Range, Prediabetes, Diabetes & Report Guide
A Fasting Blood Sugar (FBS) test measures the amount of glucose in your blood after fasting for at least 8 hours without consuming calories. It is commonly used to screen for and help diagnose prediabetes and diabetes.
In this guide, you will learn what an FBS test means, the normal fasting blood sugar range, prediabetes and diabetes values, how to prepare for the test, and how to understand your FBS report.
Important: A single abnormal blood sugar result does not always confirm diabetes. Your doctor may recommend repeat testing or another test such as HbA1c, depending on your result and overall health.
What Is a Fasting Blood Sugar (FBS) Test?
A Fasting Blood Sugar (FBS) test, also called a Fasting Plasma Glucose (FPG) test, measures blood glucose after a period of fasting.
For diagnostic testing, fasting generally means no caloric intake for at least 8 hours. Plain water is usually permitted during the fasting period, but you should follow the instructions provided by your doctor or laboratory.
FBS is commonly used for:
Screening for prediabetes and diabetes
Helping diagnose diabetes
Monitoring blood glucose in people with diabetes
Assessing blood sugar levels as part of a health check-up
Medical reference: American Diabetes Association, Standards of Care in Diabetes—2026.
Why Is the FBS Test Important?
Blood glucose provides energy for the body's cells. When glucose levels remain too high over time, it can increase the risk of health complications.
A healthcare professional may recommend an FBS test if you:
Have risk factors for diabetes
Have symptoms that may be associated with high blood sugar
Have a family history of diabetes
Have overweight or obesity
Have high blood pressure or abnormal cholesterol levels
Need monitoring for an existing diabetes condition
Are undergoing a routine health assessment
Some people with prediabetes or early diabetes may have few or no noticeable symptoms, which is one reason screening can be useful for people at increased risk.
Fasting Blood Sugar Normal Range
The following ranges are commonly used for non-pregnant adults:
| Fasting Blood Sugar | General Interpretation |
| Below 70 mg/dL | Low blood sugar may be present |
| 70–99 mg/dL | Normal fasting glucose |
| 100–125 mg/dL | Prediabetes range |
| 126 mg/dL or higher | Diabetes range; confirmation is generally required |
According to the American Diabetes Association, fasting plasma glucose of 100–125 mg/dL is in the prediabetes range, while 126 mg/dL or higher meets the glucose criterion for diabetes. In the absence of unequivocal hyperglycemia, diagnosis generally requires confirmatory abnormal testing.
Important: These ranges are general diagnostic criteria and are not a substitute for your doctor's interpretation of your individual report.
What Does an FBS Result Mean?
FBS Below 70 mg/dL
A fasting glucose below 70 mg/dL may indicate low blood sugar (hypoglycemia).
The significance depends on symptoms, medications, diabetes status and other factors. If you have symptoms such as sweating, shaking, confusion or weakness, seek appropriate medical advice.
FBS 70–99 mg/dL
This falls within the normal fasting glucose range for non-pregnant adults.
A normal result does not necessarily mean that no further testing is needed. Your doctor may consider your age, symptoms and diabetes risk factors.
FBS 100–125 mg/dL
This falls within the prediabetes range.
Prediabetes means glucose levels are higher than normal but do not meet the diagnostic threshold for diabetes. It is associated with an increased future risk of developing type 2 diabetes.
Your healthcare provider may recommend lifestyle changes and periodic glucose testing.
FBS 126 mg/dL or Higher
A fasting plasma glucose of 126 mg/dL or higher is in the diabetes range.
However, one elevated FBS result does not automatically mean that diabetes is confirmed in every situation. If there is no unequivocal hyperglycemia, your healthcare provider may recommend confirmation with repeat testing or another accepted diagnostic test such as HbA1c.
FBS Report Examples
Example 1: FBS = 92 mg/dL
A fasting glucose of 92 mg/dL is within the normal fasting range.
If you have other diabetes risk factors, your healthcare provider may still recommend periodic screening.
Example 2: FBS = 108 mg/dL
A fasting glucose of 108 mg/dL falls within the prediabetes range.
This does not mean that you have diabetes. Your doctor may recommend lifestyle changes and follow-up testing based on your overall health.
Example 3: FBS = 132 mg/dL
A fasting glucose of 132 mg/dL falls within the diabetes range.
A healthcare professional should evaluate the result. Depending on the circumstances, repeat testing or another diagnostic test such as HbA1c may be recommended to confirm the diagnosis.
How to Prepare for an FBS Test
For diagnostic fasting glucose testing:
Fast for at least 8 hours, unless your healthcare provider or laboratory gives different instructions.
Avoid food and calorie-containing drinks during the fasting period.
Plain water is generally allowed.
Avoid tea, coffee, milk, juice and other calorie-containing beverages unless your healthcare provider specifically instructs otherwise.
Take medicines only according to your doctor's or laboratory's instructions.
Tell the healthcare professional about medicines or supplements you are taking.
Follow any additional preparation instructions provided by the laboratory.
Do not stop prescribed medicines on your own simply because you are having a fasting blood test.
What Happens During an FBS Test?
An FBS test is usually performed using a blood sample collected from a vein in your arm.
The healthcare professional cleans the area, collects a small blood sample and sends it to the laboratory for analysis.
The blood collection itself usually takes only a few minutes. Report availability depends on the laboratory and the type of testing service.
Prediabetes: What Does It Mean?
Prediabetes means that blood glucose is above the normal range but below the diagnostic threshold for diabetes.
According to ADA criteria, prediabetes can include:
Not every person with prediabetes develops diabetes, but prediabetes is an important risk factor for future type 2 diabetes.
People with prediabetes should discuss appropriate follow-up and lifestyle measures with a healthcare professional.
Risk Factors for Prediabetes and Type 2 Diabetes
Risk can be higher in people who have factors such as:
Overweight or obesity
Family history of diabetes
Physical inactivity
High blood pressure
Abnormal cholesterol or triglyceride levels
Previous gestational diabetes
Other diabetes-related risk factors
Your healthcare provider can assess your individual risk and decide whether screening is appropriate.
Symptoms of High Blood Sugar
High blood sugar can sometimes occur without obvious symptoms.
Possible symptoms include:
Increased thirst
Frequent urination
Fatigue
Blurred vision
Increased hunger
Unexplained weight loss
Slow healing of wounds
Having symptoms does not by itself confirm diabetes. Blood glucose or other appropriate diagnostic testing is needed.
FBS vs PPBS
FBS and PPBS provide different information.
| FBS | PPBS |
| Measures glucose after fasting | Measures glucose after eating |
| Helps assess fasting glucose | Helps assess glucose after a meal |
| Usually performed after an overnight or specified fasting period | Commonly measured at a specified time after a meal |
| Can be used for screening and diagnosis | May be used for glucose monitoring depending on the clinical situation |
Important: PPBS should not be confused with the 75-g oral glucose tolerance test (OGTT). The OGTT is a specific diagnostic procedure in which a standardized glucose drink is given and blood glucose is measured at defined times.
FBS vs HbA1c
FBS and HbA1c measure different aspects of blood glucose.
| FBS | HbA1c |
| Measures fasting blood glucose at the time of testing | Reflects average blood glucose over roughly the previous 2–3 months |
| Requires fasting for the FBS test | Usually does not require fasting |
| Can be used for screening and diagnosis | Can also be used for screening and diagnosis |
| Can be affected by short-term changes in glucose | Provides a longer-term view of glucose levels |
Your doctor may choose one or more tests depending on your symptoms, risk factors and clinical situation.
Can Stress, Illness or Medicines Affect FBS?
Yes. Blood glucose can be affected by several factors.
Examples include:
Acute illness or infection
Physical or emotional stress
Poor sleep
Changes in eating patterns
Certain medicines, including some steroid medicines
If your result is unexpectedly high or low, tell your healthcare provider about recent illness and medicines you are taking.
How Can You Support Healthy Blood Sugar Levels?
Healthy habits can help reduce the risk of developing type 2 diabetes and support overall health.
Balanced Diet
Consider:
Eating more vegetables and high-fibre foods
Choosing whole or minimally processed foods more often
Limiting sugary drinks and excess added sugar
Paying attention to portion sizes
Choosing a balanced combination of carbohydrates, protein and healthy fats
Regular Physical Activity
Regular physical activity can help improve insulin sensitivity and blood glucose control.
Choose an activity that is appropriate for your health and fitness level. If you have a medical condition or are starting a new exercise programme, ask your healthcare professional for appropriate guidance.
Healthy Weight Management
For people who are overweight, even modest weight loss may improve metabolic health and reduce the risk of type 2 diabetes.
Adequate Sleep
Consistent, good-quality sleep is an important part of overall metabolic health.
When Should FBS Be Repeated?
The timing of repeat testing depends on your result and individual risk.
According to ADA 2026 guidance:
People with prediabetes should generally be tested yearly.
People with normal results may be retested at least every 3 years, with more frequent testing considered when risk factors or symptoms are present.
People with diabetes should follow the testing schedule recommended by their healthcare provider.
Do not rely on a fixed testing interval if your doctor has advised a different schedule for you.
When Should You Talk to a Doctor About Your FBS Result?
Consider discussing your result with a healthcare professional if:
Your FBS is repeatedly above the normal range.
Your FBS is 126 mg/dL or higher.
You have symptoms of high blood sugar.
You have a strong family history of diabetes.
You have other diabetes risk factors.
Your result does not match your usual readings.
You are taking medicines that may affect blood glucose.
A healthcare professional can decide whether repeat FBS, HbA1c, OGTT or another evaluation is appropriate.
Fasting Blood Sugar Testing at MOTi Diagnostics Centre, Mira Road
MOTi Diagnostics Centre provides blood testing services, including fasting blood sugar testing and diabetes-related laboratory tests.
Depending on availability, services may include:
For current test availability, pricing, report timing and home collection details, please contact the centre directly.
Quick FBS Reference
| FBS Result | General Meaning |
| Below 70 mg/dL | Low blood sugar may be present |
| 70–99 mg/dL | Normal fasting glucose |
| 100–125 mg/dL | Prediabetes range |
| 126 mg/dL or higher | Diabetes range; confirmation may be required |
Frequently Asked Questions
1. What is a normal fasting blood sugar level?
For non-pregnant adults, fasting plasma glucose below 100 mg/dL is generally considered normal.
2. Is 110 mg/dL diabetes?
No. A fasting glucose of 110 mg/dL falls within the prediabetes range.
3. Is fasting necessary for an FBS test?
Yes. Diagnostic fasting plasma glucose testing generally requires at least 8 hours without caloric intake.
4. Can I drink water during fasting?
Plain water is generally allowed during fasting, unless your healthcare provider or laboratory gives different instructions.
5. What FBS level indicates diabetes?
A fasting plasma glucose of 126 mg/dL or higher meets the diabetes glucose criterion. When there is no unequivocal hyperglycemia, confirmation with appropriate repeat or additional testing is generally required.
6. Is FBS better than HbA1c?
Neither test is universally “better.” They provide different information. Your healthcare provider may recommend one or both depending on your situation.
7. How long does an FBS blood test take?
Blood collection usually takes only a few minutes. The time required to receive the report depends on the laboratory.
8. Can a person have diabetes without symptoms?
Yes. Some people may have diabetes or prediabetes without noticeable symptoms. Screening can help identify abnormal glucose levels in people at increased risk.
9. Can stress affect blood sugar?
Yes. Illness, stress, sleep changes and some medicines can affect blood glucose levels.
Medical References
American Diabetes Association. Standards of Care in Diabetes—2026: Diagnosis and Classification of Diabetes.
American Diabetes Association. Standards of Care in Diabetes—2026: Prevention or Delay of Diabetes and Associated Comorbidities.
Medical Disclaimer
This article is provided for general educational purposes only. It is not intended to replace professional medical advice, diagnosis or treatment.
Blood sugar results should be interpreted in the context of your symptoms, medical history, medicines and other laboratory findings. If you have an abnormal blood sugar result or symptoms of high or low blood sugar, consult a qualified healthcare professional.
About MOTi Diagnostics Centre
MOTi Diagnostics Centre provides diagnostic and laboratory services, including blood tests and other diagnostic investigations.
For information about available tests, home sample collection, report timing and appointments, please contact MOTi Diagnostics Centre directly.
Your Health, Our Priority.
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