What It Measures#
The Fasting Blood Sugar (FBS) test measures the glucose level in your blood after an overnight fast of 8–12 hours. It is one of the primary tests used to:
- Screen for diabetes mellitus and pre-diabetes.
- Monitor daily blood-sugar control in known diabetics.
- Assess insulin resistance — the body's ability to regulate glucose after a fasting period.
Glucose is your body's main source of energy, derived from carbohydrates in your food. Insulin (produced by the pancreas) helps cells absorb glucose. When insulin is insufficient or cells become resistant to it, blood sugar rises — the hallmark of diabetes.
Who Should Get Tested#
- All adults above 35 years — annually, as recommended by Indian diabetes guidelines.
- People with a family history of diabetes.
- Overweight or obese individuals (BMI ≥ 23 for South Asians).
- Women with a history of gestational diabetes or PCOD.
- Anyone with symptoms: excessive thirst, frequent urination, unexplained weight loss, blurred vision.
- As part of a routine annual health check-up.
How to Prepare#
- Fast for 8–12 hours before the test (no food or caloric beverages). Plain water is allowed.
- Schedule an early-morning appointment (6:30–9:00 AM) for convenience.
- Continue taking prescribed medications unless your doctor advises otherwise.
- Avoid excessive physical activity the night before.
Understanding Your Results#
| Fasting Blood Sugar | Interpretation | |---------------------|---------------| | Below 100 mg/dL | Normal | | 100–125 mg/dL | Pre-diabetes (Impaired Fasting Glucose) | | 126 mg/dL or above (on two occasions) | Diabetes mellitus |
A single elevated reading needs confirmation with a repeat test or an HbA1c test. Pre-diabetes is a critical window — lifestyle changes at this stage can prevent progression to full-blown diabetes.
For known diabetics, the target fasting sugar is typically 80–130 mg/dL, but your doctor will personalise this based on your age, complications, and medication regimen.
Related Tests#
- HbA1c Test — 2–3 month average blood sugar; does not require fasting.
- Post-Prandial Blood Sugar — measures sugar 2 hours after a meal.
- Kidney Function Test — diabetes is the leading cause of CKD.
- Lipid Profile — diabetics often have associated dyslipidaemia.
Booking & Home Collection#
Book a fasting blood sugar test on PingMeDoc with early-morning home collection slots (from 6:30 AM) designed for fasting convenience. Results within 6–12 hours.