Fasting Blood Sugar Test: Purpose, Normal Range and Price

Key facts about the Fasting Blood Sugar test
Also Known As	FBS Test, Fasting Glucose Test, Fasting Plasma Glucose Test
Sample Type	Blood (Venous)
Fasting Required	Yes (8 to 10 hours mandatory, water permitted)
Report Delivery	Within 24 hours
Age Group	All age groups
Gender	All
Test Type	Enzymatic Hexokinase or Glucose Oxidase Method
Units	mg/dL or mmol/L

The Fasting Blood Sugar test, commonly known as the FBS test, is a blood test that measures the concentration of glucose in the blood after a minimum 8 to 10 hour overnight fast. Glucose is the primary fuel source for the body's cells and its levels in the blood are tightly regulated by insulin produced by the pancreatic beta cells. In the fasting state, blood glucose reflects the liver's baseline glucose output and the body's ability to maintain glucose homeostasis without any dietary input. This makes fasting glucose the most standardised and reproducible measure of glycaemic status and the cornerstone of diabetes diagnosis and monitoring. Diabetes mellitus is one of the most significant public health crises in India. With over 101 million Indians living with diabetes and an additional 136 million with prediabetes according to recent estimates, India carries the second largest diabetes burden in the world. The FBS test is the primary diagnostic tool for both diabetes and prediabetes, enabling early identification before the development of serious complications including diabetic nephropathy, retinopathy, neuropathy, and cardiovascular disease. It is a mandatory component of every annual health checkup, antenatal screening panel, and metabolic evaluation across India. The test involves a simple blood draw completed in under five minutes.

Doctors prescribe a Fasting Blood Sugar test in the following situations: Diagnosing Type 2 diabetes in patients with symptoms including excessive thirst, frequent urination, unexplained weight loss, fatigue, and blurred vision where a fasting glucose at or above 126 mg/dL on two separate occasions confirms the diagnosis. Detecting prediabetes in patients with a fasting glucose between 100 and 125 mg/dL where early identification allows lifestyle and dietary intervention to reverse or delay progression to overt diabetes before irreversible complications develop. Routine annual screening in adults above 35 years of age with risk factors including obesity, family history of diabetes, hypertension, dyslipidaemia, gestational diabetes history, and sedentary lifestyle where early detection is critical given India's extraordinary diabetes burden. Monitoring glycaemic control in patients already diagnosed with Type 1 or Type 2 diabetes where regular FBS measurements alongside HbA1c assess the effectiveness of dietary, lifestyle, and pharmacological management and guide treatment adjustments. Antenatal screening for gestational diabetes in pregnant women where elevated fasting glucose indicates impaired glucose metabolism during pregnancy that increases the risk of macrosomia, birth complications, and long-term diabetes in both mother and child. Investigating hypoglycaemia in patients with recurrent episodes of dizziness, sweating, tremor, and confusion where a low fasting glucose below 70 mg/dL confirms hypoglycaemia and guides investigation of its cause including insulinoma, medication effects, and hormonal deficiencies. Pre-operative assessment before elective or emergency surgery where baseline fasting glucose establishes glycaemic status and guides perioperative insulin and glucose management to reduce surgical risk and wound healing complications.

The Fasting Blood Sugar test measures the concentration of glucose in the blood after a minimum 8 to 10 hour fast, reported in milligrams per decilitre (mg/dL) or millimoles per litre (mmol/L). Normal Fasting Blood Sugar Range in India The standard diagnostic classification used across Indian diabetes centres and aligned with American Diabetes Association and Indian Council of Medical Research guidelines is as follows. A fasting blood glucose below 100 mg/dL is considered normal. A fasting blood glucose between 100 and 125 mg/dL is classified as impaired fasting glucose or prediabetes. A fasting blood glucose at or above 126 mg/dL on two separate occasions confirms a diagnosis of diabetes mellitus. Interpreting Fasting Blood Sugar Results A fasting glucose between 100 and 110 mg/dL represents early impaired fasting glucose where aggressive lifestyle modification including dietary changes, regular physical activity, and weight reduction can effectively reverse the trajectory toward diabetes in the majority of patients. A fasting glucose between 110 and 125 mg/dL represents advanced prediabetes with significantly elevated risk of progressing to Type 2 diabetes within 5 years, warranting consideration of pharmacological intervention with metformin alongside intensive lifestyle measures. A fasting glucose above 200 mg/dL even on a single occasion in a symptomatic patient is sufficient to confirm a diagnosis of diabetes without requiring a second confirmatory test, according to ADA guidelines followed across Indian diabetes centres.

Fasting for a minimum of 8 to 10 hours before the test is mandatory. Only water is permitted during the fasting period. Any food, beverage other than water, or chewing gum will break the fast and invalidate the result. Our team confirms preparation requirements at the time of booking. The sample should be collected in the morning after an overnight fast for the most standardised and reproducible result. Morning fasting glucose is the reference standard used in all diabetes diagnostic guidelines. Inform the phlebotomist about all medications you are currently taking, particularly insulin, oral hypoglycaemic agents, corticosteroids, thiazide diuretics, antipsychotics, and beta-blockers, as these directly affect blood glucose levels and must be disclosed for accurate interpretation. Do not take your morning diabetes medications before the test unless specifically instructed by your doctor, as insulin and sulphonylureas taken before the blood draw can lower fasting glucose and produce a falsely normal result in a poorly controlled diabetic patient. Stay normally hydrated with water during the fasting period as dehydration can concentrate blood glucose and produce a mildly elevated result.

If you are booking through the SecondMedic platform the Fasting Blood Sugar test price starts at approximately Rs. 97. The exact price will be confirmed at the time of booking through SecondMedic. If your doctor has prescribed multiple tests alongside Fasting Blood Sugar, SecondMedic health packages include FBS as part of a broader diabetes screening or metabolic panel at a significantly lower combined price.

SecondMedic provides home sample collection for Fasting Blood Sugar test across all major areas. You do not need to visit a lab or collection centre. A certified and trained phlebotomist comes to your home or workplace at your chosen time, collects the sample using sterile single-use equipment, and ensures it is transported to the NABL-accredited lab within the required time window for accurate processing. Please note that SecondMedic provides free home sample collection on all tests priced above Rs. 300. Our team will check your pincode and confirm if your address falls under our free sample collection eligibility criteria, which depends upon the lab location and phlebotomist availability. Home collection is available between 7 AM and 10 PM, seven days a week, including Sundays and public holidays. A strict 8 to 10 hour overnight fast with only water permitted is mandatory before the home collection visit for a valid and accurate fasting glucose result. Enter your pincode on the booking page or call our helpline to confirm availability at your address.