Glucose Tolerance Test (GTT): Booking, Price, and Results
About Glucose Tolerance Test (GTT)
| Field | Value |
|---|---|
| Also Known As | OGTT, Oral Glucose Tolerance Test, Glucose Challenge Test |
| Sample Type | Venous blood (multiple samples taken at timed intervals) |
| Fasting Required | Yes – 8 to 12 hours before the test |
| Report Time | 1 to 2 days |
| Recommended For | Adults of all genders with diabetes risk factors, pregnant women at 24 to 28 weeks of gestation |
| Price | Starting at ₹200 |
What Is a Glucose Tolerance Test (GTT)?
The Glucose Tolerance Test (GTT) is a blood test that checks how well your body processes sugar (glucose). It helps diagnose prediabetes, type 2 diabetes, and gestational diabetes. Also called the OGTT, or Oral Glucose Tolerance Test, it involves drinking a glucose solution and having blood drawn at set time intervals. The test uses venous blood, collected from a vein in the arm.
What Does a Glucose Tolerance Test (GTT) Measure?
The GTT evaluates how efficiently your body moves glucose from the blood into body tissues after a measured glucose load. Here is what each reading captures:
| Parameter | What It Measures |
|---|---|
| Fasting plasma glucose | Blood sugar level after at least 8 hours without food |
| 1-hour post-load glucose | How quickly glucose rises after drinking the solution |
| 2-hour post-load glucose | Whether your body has cleared the glucose within 2 hours |
| 3-hour post-load glucose | Used in some gestational diabetes protocols to track extended clearance |
| Glucose metabolism | The overall ability of the body to regulate blood sugar after a set dose |
Why Is a Glucose Tolerance Test (GTT) Done?
The Glucose Tolerance Test is requested when a doctor wants to assess how well your body manages blood sugar. Several signs and health conditions can lead to this test being prescribed.
Common Symptoms That May Require This Test
The following symptoms are among the most common reasons a doctor may order a GTT:
- Feeling unusually thirsty most of the time
- Needing to urinate much more frequently than normal
- Persistent tiredness or fatigue without a clear cause
- Unexplained weight loss
- Blurred vision
- Wounds or cuts that are slow to heal
- Recurring infections
Conditions This Test Can Help Detect
A Glucose Tolerance Test can assist in identifying several conditions related to blood sugar regulation:
- Type 2 diabetes mellitus
- Prediabetes, also called impaired glucose tolerance (blood sugar higher than normal but below the diabetes threshold)
- Gestational diabetes (diabetes that develops during pregnancy)
- Insulin resistance and impaired function of insulin-producing cells
- Reactive hypoglycaemia (low blood sugar occurring after eating)
- Hormonal disorders such as acromegaly (excess growth hormone) or Cushing syndrome (excess cortisol)
Glucose Tolerance Test (GTT) During Pregnancy
The GTT is a routine screening tool for gestational diabetes in pregnant women. It is typically carried out between 24 and 28 weeks of pregnancy. A 75 gm or 100 gm glucose load may be used depending on the protocol, and blood samples at fasting, 1-hour, and 2-hour intervals are measured to evaluate abnormal sugar regulation.
How to Prepare and What to Expect
Proper preparation helps ensure your results are accurate. Here is what you need to know before arriving for your Glucose Tolerance Test.
Do You Need to Fast?
Yes, fasting is required. You must avoid all food and drink (except water) for 8 to 12 hours before the test. For the 3 days before the test, eat normally and include at least 150 grams of carbohydrates per day in your diet. Do not restrict carbohydrates in the days leading up to the test, as this can affect your results.
Practical Tips Before Your Test
Follow these steps in the days and hours before your GTT:
- Eat a normal, unrestricted diet for at least three days before the test
- Drink only water during the fasting period; avoid tea, coffee, and milk until all samples are collected
- Inform your doctor about all medications and supplements you are taking, as some can affect results
- Maintain your usual level of physical activity in the days before the test
- Wear clothing that gives easy access to the inner arm for blood draws
- Avoid strenuous exercise on the day of the test
- Do not smoke during the test period
Step-by-Step Procedure
Here is what happens on the day of your Oral Glucose Tolerance Test:
- A healthcare professional takes a fasting blood sample from a vein in your arm after confirming you have not eaten for at least 8 hours.
- You are given a glucose solution to drink — usually containing 75 grams of glucose for non-pregnant adults or 100 grams for gestational diabetes screening.
- You remain seated at the testing facility throughout. Walking around or strenuous activity is not permitted.
- Blood samples are collected again at 30 to 60-minute intervals — typically at 1 hour and 2 hours, and sometimes at 3 hours.
- Each blood draw takes no more than 5 minutes and uses a fine needle.
- Your samples are labelled, processed, and sent to the laboratory for analysis.
Factors That Can Affect Accuracy
Several factors can influence your GTT results. Make sure your doctor is aware of the following:
- Not eating enough carbohydrates in the 3 days before the test (may produce a false high reading)
- Current medications, including pain relievers (salicylates), water pills (diuretics), and seizure medications (anticonvulsants)
- Recent illness, stress, or infection
- Prolonged bed rest or physical inactivity
- Age and body weight
Understanding Your Glucose Tolerance Test (GTT) Results
Your results should always be reviewed alongside your doctor, who will consider your full medical history. The table below shows general reference ranges for the GTT.
| Parameter | Normal | Prediabetes / At-Risk | Diabetes |
|---|---|---|---|
| Fasting glucose | Below 100 mg/dL | 100 to 125 mg/dL | 126 mg/dL or above |
| 2-hour post-load (non-pregnant) | Below 140 mg/dL | 140 to 199 mg/dL | 200 mg/dL or above |
Gestational Diabetes Thresholds (75 gm OGTT, IADPSG criteria):
| Time Point | Threshold for Gestational Diabetes |
|---|---|
| Fasting | 92 mg/dL or above |
| 1-hour | 180 mg/dL or above |
| 2-hour | 153 mg/dL or above |
These ranges are general guidelines. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
Certain situations can affect how your GTT results are interpreted:
- Oral contraceptive pills may produce a mild rise in blood glucose readings.
- Medications such as salicylates, diuretics, and anticonvulsants can reduce insulin secretion and alter results.
- Stress, acute illness, and active infections can temporarily raise blood glucose levels.
- Conditions such as polycystic ovary syndrome (PCOS) and Cushing syndrome may affect glucose regulation and, therefore, test outcomes.
How to Maintain Healthy Levels
These general wellness habits can support healthy blood sugar regulation:
- Eat a balanced diet that includes whole grains, vegetables, lean proteins, and limited refined sugars.
- Aim for at least 150 minutes of moderate physical activity each week, such as brisk walking or cycling.
- Maintain a healthy body weight, as excess weight is closely linked to impaired glucose tolerance.
Lupin Diagnostics Glucose Tolerance Test (GTT) Price and Home Collection
The Glucose Tolerance Test (GTT) at Lupin Diagnostics starts at approximately ₹200, with home sample collection available across major cities in India. The table below shows indicative prices across major cities in India:
| City | Approximate Price (₹) |
|---|---|
| Mumbai | ₹200 to ₹1000 |
| Bengaluru | ₹150 to ₹900 |
| Chennai | ₹260 to ₹600 |
| Hyderabad | ₹190 to ₹850 |
| Kolkata | ₹250 to ₹750 |
| Pune | ₹200 to ₹900 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
- Select the test on the Lupin Diagnostics website.
- Choose your city and preferred time slot.
- Opt for home sample collection by a certified phlebotomist, or visit your nearest Lupin Diagnostics centre.
- Receive your report via email or WhatsApp within the stipulated turnaround time.
Home Collection
Lupin Diagnostics offers home collection for the Glucose Tolerance Test across multiple cities in India. A certified phlebotomist visits your home at your chosen time, collecting samples at the required intervals. All samples are processed in NABL-accredited laboratories, and your digital report is delivered directly to you.
Frequently Asked Questions
The 75 gm Glucose Tolerance Test is the standard version used to screen and diagnose type 2 diabetes and prediabetes in non-pregnant adults. The 100 gm version is typically used to confirm gestational diabetes in pregnant women following an initial positive screen. Your doctor will advise which version is appropriate for you.
The GTT can take up to 3 hours from start to finish. You will need to stay at the testing facility or remain available at home during this time, as blood samples are drawn at scheduled intervals after you drink the glucose solution.
Water is allowed during the fasting period before the test. Once you have consumed the glucose solution, you may continue drinking water, but you must avoid all food, other beverages, and smoking until every sample has been collected.
Yes, the Oral Glucose Tolerance Test is considered safe during pregnancy. As with any blood test, you may feel a brief sting at the needle site or notice a small bruise afterwards. These effects are minor and temporary.
If you vomit after drinking the glucose solution, the test cannot continue because incomplete absorption of glucose would make the results unreliable. The test will need to be rescheduled for another day. Let the healthcare professional know immediately if you feel unwell.
Yes, several medications can alter GTT results. These include common pain relievers, water pills, and seizure medications. Inform your doctor about everything you are taking before the test. Do not stop any medication without first consulting your doctor.
The Glucose Tolerance Test measures blood sugar at specific time points after a glucose load, making it useful for diagnosing diabetes and gestational diabetes. The HbA1c test, on the other hand, reflects your average blood sugar over the past 2 to 3 months. The GTT is preferred when screening for gestational diabetes, as the HbA1c test is not suitable for that purpose.
Glucose Tolerance Test (GTT): Booking, Price, and Results
