GTT (Glucose Tolerance Test – 2 Hours) in Kolkata | Home Collection & NABL-Certified Results

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What is a GTT (Glucose Tolerance Test – 2 Hours)?

The GTT (Glucose Tolerance Test – 2 Hours) is a specialized diagnostic procedure used to evaluate how efficiently your body clears sugar from the bloodstream. Unlike a standard blood sugar test, a GTT involves measuring your body's response to a specific glucose challenge. It is considered the gold standard for diagnosing impaired glucose tolerance, Type 2 diabetes, and gestational diabetes in pregnant women — revealing how your system handles a surge in sugar levels over a controlled period.

⚠ Important: A fasting period of 8 to 12 hours is required before this test. Only water is allowed during fasting. You must remain seated and avoid physical activity, eating, drinking (except water) and smoking during the 2-hour test period.

The Importance of Glucose Tolerance Testing

Standard fasting tests sometimes miss early stages of metabolic issues. The GTT is critical for several clinical reasons:

• Early Detection — Identifies Impaired Glucose Tolerance (IGT) which may not be visible in a routine fasting blood sugar test
• Gestational Diabetes Screening — Essential for pregnant women between 24–28 weeks to ensure the health of both mother and baby
• Insulin Resistance Assessment — Helps doctors understand if the pancreas is producing enough insulin or if the body's cells are resisting it
• Comprehensive Mapping — Provides a curve of how sugar levels rise and fall, offering a deeper insight into your metabolic health

How is the GTT Test Performed?

Step-by-Step Procedure:

1. Fasting sample — A blood sample is collected after 8–12 hours of fasting to establish your baseline blood sugar level
2. Glucose drink — You are given a standard 75g oral glucose solution to drink within 5 minutes
3. Wait period — You must remain seated and rest for 2 hours. No eating, drinking (except water), smoking or physical activity is allowed
4. 2-hour sample — A second blood sample is collected exactly 2 hours after the glucose drink
5. Report — Both fasting and 2-hour values are reported together for your doctor to interpret

Normal GTT (2-Hour) Reference Values

Time Point	Normal	Prediabetes	Diabetes
Fasting (0 min)	Below 100 mg/dL	100 – 125 mg/dL	126 mg/dL or above
2-Hour Post Glucose	Below 140 mg/dL	140 – 199 mg/dL	200 mg/dL or above

Your doctor will interpret both values together alongside your symptoms and medical history.

When is a GTT Recommended?

Your doctor may recommend a GTT if:

• Your fasting blood sugar is borderline (100–125 mg/dL)
• You are pregnant between 24–28 weeks (gestational diabetes screening)
• You have symptoms of diabetes — increased thirst, frequent urination, fatigue, blurred vision
• You have PCOS (Polycystic Ovarian Syndrome) with insulin resistance
• You have a strong family history of Type 2 diabetes
• You are overweight or obese with risk factors for diabetes
• Your HbA1c is borderline and requires confirmation

GTT vs FBS vs HbA1c — What is the Difference?

Test	What it Measures	Best For
FBS	Blood sugar after 8–12 hours fasting	Initial diabetes screening
GTT (2-Hour)	Blood sugar response to glucose challenge	Diagnosing prediabetes & gestational diabetes
HbA1c	Average blood sugar over 3 months	Long-term diabetes management
PPBS	Blood sugar 2 hours after a meal	Post-meal glucose monitoring

GTT Test Price in Kolkata

GTT (Glucose Tolerance Test – 2 Hours) Price: ₹220
Fasting of 8–12 hours required  |  2-hour centre visit needed  |  Free home collection above ₹2,000

Important Preparation Instructions

• Fast for 8–12 hours before the test — only plain water is allowed
• Avoid strenuous exercise the day before the test
• Inform your doctor of any medications you are taking — some can affect glucose levels
• Do not smoke during the fasting period or during the 2-hour test window
• Remain seated and resting during the full 2-hour wait — physical activity will affect results
• If you feel unwell during the test (sweating, dizziness, nausea) inform the staff immediately

Tests Commonly Ordered Alongside GTT

• Fasting Insulin — assesses insulin resistance alongside glucose tolerance
• HbA1c — confirms long-term average blood sugar control
• Lipid Profile — diabetics are at higher risk of cardiovascular disease
• Kidney Function Test (KFT) — checks for early diabetic kidney damage
• Urine Microalbumin — detects early diabetic nephropathy

Note on Home Collection for GTT

The GTT test requires two blood samples collected exactly 2 hours apart, with a glucose drink administered in between. This test is best performed at our Nagerbazar centre where you can rest comfortably during the 2-hour waiting period. However, if you are unable to visit the centre, please WhatsApp us to discuss home collection arrangements.

📞 Book GTT Test via WhatsApp — +91 8660434628

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→ Apollo Diagnostics Nagerbazar → Full List of Individual Tests → Book Home Collection → Full Body Checkup Packages

Frequently Asked Questions

Q1. What is the GTT test used for?

The GTT (Glucose Tolerance Test) is used to evaluate how efficiently your body processes sugar. It is the gold standard for diagnosing impaired glucose tolerance, Type 2 diabetes, and gestational diabetes in pregnant women.

Q2. What is the normal GTT 2-hour value?

A normal 2-hour post-glucose value is below 140 mg/dL. Values between 140–199 mg/dL indicate prediabetes (impaired glucose tolerance). A value of 200 mg/dL or above on two separate occasions confirms diabetes.

Q3. How many hours of fasting is required for GTT?

A fasting period of 8 to 12 hours is required before the GTT. Only plain water is allowed during the fasting period. Avoid tea, coffee, food, medications and smoking until after your fasting sample is collected.

Q4. What is the GTT test price at Apollo Diagnostics Kolkata?

The GTT (Glucose Tolerance Test – 2 Hours) price at Apollo Diagnostics is ₹220. The test involves two blood samples collected 2 hours apart.

Q5. Can I eat or drink during the 2-hour GTT waiting period?

No. During the 2-hour waiting period after the glucose drink, you must not eat, drink (except plain water), smoke or engage in physical activity. Any of these can affect your glucose levels and invalidate the test result.

Q6. Why is GTT recommended during pregnancy?

GTT is the standard screening test for gestational diabetes, typically recommended between 24–28 weeks of pregnancy. Undetected gestational diabetes can cause complications for both mother and baby including high birth weight, premature delivery and increased risk of Type 2 diabetes later in life.

Q7. What is the difference between GTT and FBS?

FBS measures blood sugar after fasting and gives a baseline glucose reading. GTT goes further — it measures how your body responds to a glucose challenge over 2 hours. GTT can detect prediabetes and gestational diabetes that a simple FBS test might miss.

Q8. Is home collection available for GTT test in Kolkata?

The GTT requires two blood draws 2 hours apart with a glucose drink in between, so it is best performed at our Nagerbazar centre. Please WhatsApp us on +91 8660434628 to discuss your options if you are unable to visit the centre.

Q9. How long does it take to get GTT results?

GTT results are typically ready within a few hours after your second blood sample is collected. Reports are delivered digitally to your WhatsApp or email.

Q10. Which centre processes my GTT sample in Kolkata?

All samples are processed at Apollo Diagnostics Nagerbazar — Nandarani Apartment, 8A Narasingha Avenue, Nagerbazar, Dum Dum, Kolkata 700074. Our lab is NABL-certified and ISO-certified.