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FBS (Fasting Blood Sugar)

FBS (Fasting Blood Sugar)

Also referred as
Glucose - Fasting (F)
Fasting Blood Sugar
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The FBS (Fasting Blood Sugar) test measures the glucose (sugar) level in the blood after overnight fasting. This test is done when a person experiences symptoms of high or low blood sugar levels or to assess a person’s risk for diabetes. It is often done as part of a routine health checkup.

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Overnight fasting required for 8 to 12 hours
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Understanding FBS (Fasting Blood Sugar)

Glucose is the primary energy source for the body. Carbohydrates in the food are broken down into glucose, which is then absorbed into the bloodstream and transported to the cells for energy. Insulin, produced by the pancreas, regulates the blood glucose level in the body. A lack of insulin or its reduced effectiveness can result in high blood glucose levels.

High blood glucose levels can be a sign of diabetes or prediabetes (a condition where a person has high blood glucose levels but not yet at a level that qualifies as diabetes). Early detection and treatment of diabetes are essential to prevent complications such as heart disease, kidney damage, and nerve damage. An FBS test, also known as glucose fasting test helps screen for prediabetes and diabetes and checks the effectiveness of medications or lifestyle changes for diagnosed people.

Fasting for at least 8–12 hours is recommended before undergoing the FBS (Fasting Blood Sugar) test. Do not eat or drink anything other than water during the fasting period. It is also important to inform the doctor about any medicines being taken, as some may affect the blood glucose levels and need to be adjusted or temporarily discontinued before the test.

FBS test result ranges may vary across the laboratories depending on the methodology and laboratory guidelines. Do not self-medicate. Always consult your doctor to understand your test results. The results will help them understand your condition, suggest lifestyle changes like diet and exercise, to decide if you need medication, and create a treatment plan.

What Are the Symptoms or Conditions That May Require the FBS (Fasting Blood Sugar) Test?

You may need the FBS (Fasting Blood Sugar) test if you experience symptoms of high or low blood sugar, such as:

  • Excessive thirst or hunger.
  • Frequent urination, especially at night.
  • Blurred vision.
  • Persistent fatigue or irritability.
  • Unexplained weight loss or gain.
  • Slow-healing wounds or frequent infections.

You may also need this test if:

  • Your doctor suspects prediabetes or diabetes.
  • You are overweight or have a sedentary lifestyle.
  • You have a family history of diabetes.
  • You have high blood pressure, cholesterol, or heart disease.
  • You had gestational diabetes during pregnancy.

When Would I Need the FBS (Fasting Blood Sugar) Test?

You may need the FBS (Fasting Blood Sugar) test if:

  • You have symptoms of diabetes.
  • You are younger but overweight, inactive, or have a family history of diabetes.
  • You have abnormal cholesterol or high blood pressure.
  • You are pregnant or have had gestational diabetes in the past.
  • You experience frequent thirst, urination, or fatigue.
  • Your doctor is monitoring your diabetes or medication response.

How Do I Prepare for the FBS (Fasting Blood Sugar) Test?

Do I need to fast or stop any medications before the FBS (Fasting Blood Sugar) test?

Fasting for at least 8–12 hours is recommended before undergoing the FBS (Fasting Blood Sugar) test. Do not eat or drink anything other than water during the fasting period. It is also important to inform the doctor about any medicines or supplements being taken. Your doctor will guide you if any temporary adjustments are needed before the test.

How is the FBS (Fasting Blood Sugar) done?

  • The FBS (Fasting Blood Sugar) is done by collecting a small amount of blood from a vein, usually in the arm. 
  • The procedure is quick, minimally invasive, and generally causes only slight discomfort.

What happens during the FBS (Fasting Blood Sugar) test?

  • You will be seated comfortably with your arm supported on a flat surface or armrest.
  • A tourniquet (elastic band) is tied around your upper arm to make the veins more visible and easier to locate.
  • The phlebotomist identifies a suitable vein for blood collection.
  • The puncture site is then cleaned thoroughly with an alcohol swab to reduce the risk of infection.
  • A thin, sterile needle is gently inserted into the vein, and a small amount of blood is collected into a test tube.

What happens after the FBS (Fasting Blood Sugar) test?

  • Once enough blood is collected, the tourniquet is released and the needle is removed.
  • A cotton ball or gauze is placed on the site, followed by a small bandage or dressing to stop any bleeding.
  • The blood sample is carefully labeled with your details and sent to the laboratory for analysis.
  • You can resume your daily routine after the test is done.

Is the FBS (Fasting Blood Sugar) test painful?

No, the FBS (Fasting Blood Sugar) test is generally safe and painless. However, you may feel slight discomfort during blood sample collection, but the chances of serious complications are extremely rare.

How Long Does the FBS (Fasting Blood Sugar) Test Take?

The procedure is quick, simple, and safe. It requires only a small blood sample and is completed within a short duration.

When Will I Get the Results?

The availability of your test report may vary depending on your location and the laboratory where the test is conducted. In general, Tata 1mg provides the results within the stipulated time after sample collection.

When Should I Consult a Doctor After the Test?

You should consult your doctor if:

  • Your test results are outside the normal range.
  • You have symptoms of high or low blood sugar.
  • You experience persistent fatigue, thirst, or blurred vision.

Are There Any Risks Associated with the FBS (Fasting Blood Sugar) Test?

The FBS (Fasting Blood Sugar) test is safe, with usually minimal or no risk that resolves on its own:

  • Small bruise, pinch, or slight tenderness at the puncture site
  • Occasional lightheadedness if you are sensitive to needles or blood
  • Rarely, infection or blood vessel injury

Note: If you have a bleeding disorder or take blood thinners, inform the phlebotomist beforehand.

Lifestyle Tips to Manage Your Blood Glucose Levels:

🥤 Hydration: Drink enough water to support health and keep blood sugar stable.

🥙 Eat (Diet): Focus on whole grains, vegetables, lean proteins, healthy fats, nuts, and seeds.

🚴‍♀️ Activity (Exercise): Regular exercise like walking, cycling, or strength training helps manage blood sugar and maintain a healthy weight.

😴 Lifestyle (Sleep): Get quality sleep to help regulate blood sugar.

👨‍⚕️ Talk to Your Doctor (Consult): Review FBS results and adjust your diabetes plan as needed.

💊 Habits (Supplements): Take supplements like magnesium or chromium only if your doctor advises as these supplements help regulate insulin sensitivity and support glucose metabolism.

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What does FBS (Fasting Blood Sugar) measure?

The FBS (Fasting Blood Sugar) test measures the glucose level in the body under overnight fasting conditions. Glucose is the body's energy currency and is broken down through metabolism to produce energy. Hormones and enzymes produced by the liver and pancreas control this process. The hormone insulin, produced by the pancreas, regulates blood glucose levels. When these levels are high, such as after a meal, insulin is secreted to transport glucose into cells for energy production. Elevated glucose levels in the body after fasting may indicate a risk of developing prediabetes or diabetes, which can be of two types: type 1, caused by little or no insulin production, and type 2, caused by insulin resistance or decreased insulin production.

What Do the Results Mean?

Pathological Factors 

Test Parameter

Interpretation (possible causes)

Normal

  • No diabetes

Borderline/Elevated

  • Pre-diabetes (can be due to insulin resistance, and other risk factors like obesity, unhealthy diet, sedentary lifestyle, etc.)

High levels

  • Diabetes

Physiological Factors

🧒 Age: Glucose levels may increase slightly with age, even in healthy individuals.

🫄 Pregnancy: Hormonal changes during pregnancy can temporarily alter blood sugar levels.

Lifestyle Factors

🍽️ Diet: High sugar intake, irregular meals can affect fasting glucose readings.

😴 Sleep: Poor sleep quality, irregular sleep patterns, or chronic stress may elevate fasting glucose levels.

🚬 Smoking & Alcohol: Both can interfere with insulin function and lead to inaccurate blood sugar results.

Disclaimer: This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment. Always consult your healthcare provider for personalized guidance.

What Do Normal Fasting Blood Sugar Levels Mean?

Normal fasting blood sugar levels suggest that your body is efficiently regulating glucose through proper insulin function. It indicates a stable energy balance and a lower risk of developing diabetes or related metabolic issues.

What Do High Levels of Fasting Blood Sugar Indicate?

High fasting blood sugar levels may point to insulin resistance or reduced insulin activity in the body. It can be an early sign of prediabetes or diabetes and is often linked to factors such as poor diet, stress, inactivity, or certain health conditions.

What to Do if Your Fasting Blood Sugar Is Higher Than Normal?

If your fasting blood sugar level is higher than normal, it is important to follow up with your doctor. Many people successfully manage or reverse borderline results with healthy lifestyle changes such as balanced nutrition, regular physical activity, adequate sleep, and medical guidance when required.

What Do Low Levels of Fasting Blood Sugar Indicate?

Low fasting blood sugar levels may indicate that your body has more insulin than needed or that you have not eaten enough before the test. It can also occur due to certain medications or underlying medical conditions. Always consult your healthcare provider to understand the reason and manage it safely.

Can Fasting Blood Sugar Results Be Inaccurate?

Certain conditions or external factors such as skipping meals, lack of sleep etc., can affect FBS results. If your readings do not align with your symptoms or overall health, your doctor may recommend repeating the test or performing additional investigations to confirm accuracy.

What Factors Can Affect Fasting Blood Sugar Results?

Though a reliable test, some circumstances can influence accuracy:

  • Eating or drinking anything (other than water) before the test
  • Dehydration or prolonged fasting
  • Stress or lack of sleep before testing
  • Certain medications 
  • Sunburn
  • Coffee intake
  • Alcohol

What Follow-Up Tests May Be Required?

Table: Tests Commonly Ordered Alongside Fasting Blood Sugar Test:

Test Name

Primary Purpose

HbA1c (Glycosylated Hemoglobin)

Measures average blood sugar over 2–3 months

Postprandial Blood Sugar (PPBS)

Checks glucose levels 2 hours after eating

RBS (Random Blood Sugar)

Measures blood sugar at any time, without the need for fasting.

Oral Glucose Tolerance Test (OGTT)

Evaluates how the body processes sugar

Lipid Profile

Evaluates cholesterol and overall heart risk

Urine Microalbumin

Detects early signs of kidney damage

Liver/Kidney Function Tests

Monitors organ health and diabetes-related complications

Thyroid Profile

Assesses metabolism and hormone balance

How Does FBS (Fasting Blood Sugar) Differ from Other Glucose Blood Tests?

  • PPBS (Postprandial Blood Sugar): Measures blood sugar 2 hours after eating a meal.
  • RBS (Random Blood Sugar): Measures blood sugar anytime, without fasting.
  • OGTT (Oral Glucose Tolerance Test): Measures blood sugar before and after consuming glucose.
  • Glycated Hemoglobin (HbA1c): Reflects average blood sugar over the past 2–3 months

FAQs related to FBS (Fasting Blood Sugar)

The FBS (Fasting Blood Sugar) test is a blood test that helps determine blood sugar levels after 8-12 hours of fasting.
The FBS (Fasting Blood Sugar) test is important because it helps determine the risk of diabetes, and other glucose metabolism disorders.
Do not eat or drink anything except water for 8-12 hours before the test. It is also important to inform your doctor about any medications you are taking, as some of them can affect blood glucose levels and may need to be adjusted or temporarily discontinued before the test.
The risks associated with an FBS test are generally minimal. However, some people may experience mild pain or discomfort at the site from where the blood sample is taken.
Yes, the Fasting Blood Glucose test is commonly used during pregnancy to screen for gestational diabetes, which is a type of diabetes that develops during pregnancy.
Hypoglycemia (low blood sugar) is a condition when the blood sugar levels fall below the normal levels.
Symptoms of hypoglycemia include excessive sweating, fatigue, frequent hunger, shivering or trembling, confusion, and blurred vision.
Hyperglycemia (high blood sugar) is a condition when the blood sugar level increases above the normal levels. This condition may indicate prediabetes or diabetes.
Symptoms of hyperglycemia include increased thirst, frequent urge to urinate, weakness, tiredness (fatigue), blurred vision, and slow wound healing.
The most common risk factors for diabetes include being obese or overweight with low physical activity, having a family history of diabetes, or having high blood pressure. Other reasons that can cause diabetes include low good cholesterol or high triglyceride levels, polycystic ovarian syndrome, or cardiovascular diseases.
Yes, blood sugar levels may increase due to certain medications, during pregnancy, and temporarily due to stress.
If diabetes is not well controlled, it can cause problems in many parts of the body. This includes heart issues like coronary artery disease, damage to the eyes (diabetic retinopathy), and nerve problems (diabetic neuropathy). It can also affect the kidneys (diabetic nephropathy) and lead to foot complications such as ulcers or infections. Other possible issues include hearing difficulties and skin problems.
Additional tests that may help diagnose diabetes include HbA1c, urine glucose, blood glucose-postprandial (PP), random blood glucose, and oral glucose tolerance tests.
The price of the FBS (Fasting Blood Sugar) test can vary depending on your location, diagnostic laboratory, and whether the test is done as a single test or as part of a health screening package.
You can control diabetes by staying active, eating a balanced diet, maintaining a healthy weight, and checking your blood sugar regularly. If needed, take medications or insulin as prescribed by your doctor.
Type 2 diabetes happens when your body does not use insulin properly or does not make enough of it. This causes high blood sugar, which can affect your health if not managed.
A person with diabetes should monitor blood sugar regularly, eat a diabetes-friendly diet, exercise, take medications as prescribed, manage stress, and have regular checkups to prevent complications.
Prediabetes is a condition where blood sugar levels are higher than normal but not high enough to be diagnosed as diabetes. It increases the risk of developing type 2 diabetes. Managing prediabetes involves making lifestyle changes such as eating a healthy diet, increasing physical activity, losing excess weight, and monitoring blood sugar regularly.
Impaired glucose tolerance (IGT) is defined as two-hour glucose levels of 140-199 mg/dL on a 75 gm oral glucose tolerance test, meaning your blood sugar is higher than normal putting you at an increased risk of developing type 2 diabetes, but you do not have diabetes yet. If your fasting blood sugar is 126 mg/dL or higher, or your 2-hour post-meal blood sugar is 200 mg/dL or higher, confirmed on another day, it indicates diabetes. IGT is a warning sign, and healthy lifestyle changes can help lower your risk.
The price for this test can vary depending on the location and the laboratory.
You can book a fasting blood sugar test at any Tata 1mg lab near you. Simply check for the nearest lab location and schedule a convenient date and time for your test.
Tata 1mg ensures accurate lab test results through certified laboratories that use advanced technology and adhere to stringent quality control measures. This commitment to high standards guarantees reliable results.

FBS (Fasting Blood Sugar) test price for other cities

Price inKolkataRs. 79
Price inHyderabadRs. 80
Price inMumbaiRs. 89
Price inNew DelhiRs. 79
Price inPuneRs. 79

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FBS (Fasting Blood Sugar)