Glucose FBS Fasting Blood Sugar
Also Known As
Test Parameters Included
- Serum Glucose (Fasting): Glucose is the primary fuel for your body's cells. During a fast, the liver releases stored sugar to maintain a steady energy supply. In a healthy individual, insulin acts as a "key," allowing this sugar to enter cells and keeping the blood levels within a narrow range. If insulin is insufficient or ineffective, fasting glucose levels will rise.
Department
Methodology
Sample Required
Preparation
Schedule Report
12 Hours
Emergency Report
Yes
Frequently Asked Questions
Why do I need to fast for exactly 8–12 hours?
Less than 8 hours may show sugar from your last meal; more than 12 hours can trigger a "starvation response" where the liver releases extra sugar, skewing the result.
Can I drink black coffee while fasting?
No. Caffeine can stimulate the liver to release stored glucose, potentially causing a "False High" result.
Why is the blood collected in a grey-top (Sodium Fluoride) tube?
Sodium Fluoride stops the blood cells from "eating" the glucose in the tube, ensuring the level stays the same from the moment of collection until it reaches the lab.
Why does the report take 2–3 hours?
While the chemical reaction is fast, the lab performs quality control checks and equipment calibration to ensure the hexokinase precision is 100%.
Can stress affect my sugar level?
Yes. Stress releases "Cortisol," which naturally increases blood sugar. Try to stay relaxed during the blood draw.
Is 105 mg/dL a dangerous level?
It indicates "Prediabetes." It is a warning sign to adjust your diet and activity to prevent full-blown diabetes.
Can I brush my teeth?
Yes, but avoid swallowing toothpaste, as some contain artificial sweeteners that could trigger a metabolic response.
What is the "Dawn Phenomenon"?
It’s a natural rise in blood sugar that occurs in the early morning as the body prepares for the day.
Does a single high reading mean I have diabetes?
No. Diagnosis usually requires two separate high readings or a high HbA1c result.
Can I drink water before the test?
Yes, plain water is encouraged to keep you hydrated and make the blood draw easier.
Does smoking affect fasting sugar?
Yes, nicotine can increase insulin resistance, leading to higher fasting sugar readings over time.
Is this more accurate than a finger-prick test?
Yes. Laboratory testing using the hexokinase method on venous blood is significantly more accurate than home glucometers.
Can exercise lower my sugar immediately?
While long-term exercise helps, intense exercise immediately before a test can actually cause a temporary spike in sugar.
Why check FBS instead of just HbA1c?
FBS shows your current baseline, while HbA1c shows a long-term average. They are complementary; you need both for a full picture.
How often should I test my FBS?
Healthy adults should test once a year. If you are in the prediabetic range, every 3 to 6 months is often recommended.
Test Description
Test Code
G04
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