Glucose Tolerance Test (GTT, 75 Grams)
The 75g GTT measures your body's ability to handle a glucose load. Blood sugar is measured fasting and at 1 and 2 hours after drinking 75 grams of glucose. Used to diagnose diabetes and prediabetes.
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What the Glucose Tolerance Test (GTT, 75 Grams) test tells you
The 75-gram oral glucose tolerance test is the single-step version of the same idea: give the body a standard, measured sugar load and watch how it copes. Unlike the two-stage pregnancy pathway, this one test is used on its own, both inside and outside pregnancy. Outside pregnancy it is the test that settles questions a fasting glucose alone leaves open — whether glucose handling has become impaired, or whether the picture amounts to diabetes. In pregnancy it is used as a one-step alternative to the older screen-then-confirm approach.
It is a timed procedure and not a single blood draw. You come having fasted overnight, and a first sample is taken before you drink anything. You then drink the measured 75-gram glucose solution and remain at the facility while further samples are taken at set intervals — usually at one hour and at two hours, depending on what your doctor has requested. Throughout the wait you should sit quietly without eating, smoking or walking about, because muscle activity pulls glucose out of the blood and would change the readings in a way the test cannot account for.
The value of the exercise is that it exposes something a fasting measurement can hide. Many people maintain a fasting glucose that looks unremarkable while their blood sugar rises too far and falls too slowly after a meal, which is often the earliest visible sign that insulin is no longer working efficiently. Watching the response over time reveals that pattern directly. As with any dynamic test, preparation matters as much as the procedure: eating your normal diet beforehand, particularly your usual carbohydrate, is essential, because several days of low carbohydrate intake makes the body handle the drink less well and can make the result look worse than your everyday physiology.
Ordered when fasting glucose is borderline, to confirm prediabetes, or as an alternative diagnostic method for gestational diabetes using international criteria.
Blood sugar can look unremarkable while fasting yet rise too far after food, and only a timed challenge shows that pattern.
When a fasting glucose or HbA1c sits in an ambiguous zone, this test gives a clearer answer about how the body handles sugar.
It can be used as a single procedure to assess gestational diabetes, without a separate screening step beforehand.
Impaired glucose handling often appears years before diabetes does, and finding it early is when lifestyle change has most effect.
Reasons your doctor may request the Glucose Tolerance Test (GTT, 75 Grams) test
Your doctor may order this test for any of the reasons below. Some are routine checks, others follow specific symptoms or an earlier result.
Clarifying a borderline result
A fasting glucose or HbA1c result sitting in a borderline zone that needs clarification.
Pregnancy assessment & follow-up
Assessment for gestational diabetes using the single-step approach in pregnancy.
Follow-up after a previous pregnancy affected by gestational diabetes.
Family history & insulin resistance
A strong family history of type 2 diabetes alongside features of metabolic risk.
Polycystic ovary syndrome or another condition associated with insulin resistance.
Pick a morning slot online or on WhatsApp — come fasted per the prep note below.
A DHA-licensed nurse collects your sample at home or in the office — free home collection.
A physician-reviewed, easy-to-read report lands securely by WhatsApp and email.
A timed test of blood sugar after a 75g glucose load.
Glucose Tolerance Test (GTT, 75 Grams)
A timed test of blood sugar after a 75g glucose load.
Blood sugar is measured at several time points (fasting, 1h and 2h). Each value is interpreted against its own target. See your detailed report.
This test is reported descriptively rather than on a numeric scale — each finding below explains what your report may say.
This information is for general education only and is not medical advice. Reference ranges can vary by laboratory, age, sex, and individual factors. Always consult your physician or doctor to interpret your results.
What a higher result can point to
- Impaired glucose tolerance or diabetes, in which insulin cannot clear the load efficiently.
- Gestational diabetes, where the hormones of pregnancy add to insulin resistance.
- Steroid treatment and some other medicines that raise blood sugar while they are being taken.
- Restricting carbohydrate in the days before the test, which reduces the body's readiness to handle a large sugar load.
- Acute illness, infection or major physical stress at the time of testing, which temporarily raise blood sugar.
What a lower result can point to
- An exaggerated or delayed insulin response, in which too much insulin arrives after the peak and drives the level down.
- Glucose-lowering medicine taken before the test, when it should have been delayed until afterwards.
- Previous stomach or weight-loss surgery, after which sugar is absorbed rapidly and then cleared abruptly.
These are possibilities, not diagnoses. A single value outside the reference range is interpreted alongside your symptoms, history and other tests — your doctor decides what it means for you.
What this test cannot tell you
- The whole sequence must be completed for the result to mean anything; leaving early, eating or vomiting partway through usually means repeating it on another day.
- The result reflects glucose handling on that day, and illness, stress, steroid treatment or poor preparation can all shift it.
- Restricting carbohydrate beforehand makes the result look worse rather than better, so an unprepared test can mislead.
- It describes how the body handles a standard load, not how it handles your usual meals, and is interpreted alongside HbA1c and the clinical picture rather than alone.
Risks of the blood draw
- Mild bruising or brief soreness where the needle went in.
- Occasional lightheadedness, which settles after a few minutes of rest.
- Bleeding or infection at the site, which is rare with sterile single-use equipment.
- 1This is a timed procedure with several blood samples, not a single draw, and you stay at the facility throughout.
- 2An overnight fast is required, with only plain water before the first sample.
- 3Eat your normal diet, including your usual carbohydrate, in the days beforehand.
- 4Sit quietly between samples: eating, smoking and walking about all change the result.
- 5It can reveal impaired glucose handling in people whose fasting result looks unremarkable.
Frequently Asked Questions
Everything you need to know about the Glucose Tolerance Test (GTT, 75 Grams) test. Can't find what you're looking for?
Talk to our team→A fasting result shows only your starting point. Many people hold a reasonable fasting level while their blood sugar climbs too high and clears too slowly after eating. Sampling at set times after a standard drink exposes that pattern, which is often the earliest sign that insulin is losing efficiency.
It is the single-step approach: one fasting sample, one measured drink and timed samples afterwards. The alternative pregnancy pathway uses a shorter non-fasting screening challenge first and only proceeds to a longer test if that is abnormal. Which route is used depends on the protocol your doctor follows.
The body adapts to what it is regularly given. After several days of low carbohydrate intake it becomes less prepared to process a large sugar load quickly, so blood sugar rises higher and falls more slowly than it normally would. The result then reflects the preparation rather than your everyday physiology.
Plain water is usually allowed; ask the team. Coffee, tea, other drinks, food and smoking are not, because caffeine and nicotine affect how glucose is handled and any food adds sugar. Anything taken during the waiting period makes the readings unreliable.
The 75g GTT measures your body's ability to handle a glucose load. Blood sugar is measured fasting and at 1 and 2 hours after drinking 75 grams of glucose. Used to diagnose diabetes and prediabetes.
Ordered when fasting glucose is borderline, to confirm prediabetes, or as an alternative diagnostic method for gestational diabetes using international criteria.
Yes. We recommend fasting for 10-12 hours before your Oral Glucose Tolerance (75g) test; plain water is fine. Overnight fasting (8–14 hours) is required. A high-carbohydrate diet for 3 days before the test is recommended.
The Oral Glucose Tolerance (75g) test uses a plasma (naf) sample, collected quickly by our DHA-licensed phlebotomist with minimal discomfort.
Results for the Oral Glucose Tolerance (75g) test are typically ready within 1 day. You will receive a secure digital report, and your Smart Report highlights anything outside the normal range.
The Oral Glucose Tolerance (75g) test is AED 170, which includes free home sample collection and a physician-reviewed report. You can also build a custom panel and pay only for the markers you choose.
Yes. A DHA-licensed phlebotomist can collect your sample at home or the office anywhere in Dubai at no extra cost, 7 days a week. See how it works.
It is commonly chosen by adults at metabolic risk. If you are not sure it is right for you, our care team is happy to advise.
Add the Oral Glucose Tolerance (75g) test to your cart and complete the short booking wizard, choosing home collection or a lab visit. Guest checkout lets you book without creating an account.
Yes. It is processed at our EIAC-accredited laboratory (ISO 15189:2022) under DHA license 0046381 and verified by board-certified pathologists.
Every report includes reference ranges and plain-language notes. If you have questions, our care team can arrange a clinician review — just get in touch.
Absolutely. Add it to a curated health package or bundle it with any of our 160+ biomarkers, often from a single sample in one visit.