Medically reviewed: 11 September 2026 · Last updated: 11 September 2026
Why most people with prediabetes feel fine, and which test actually finds it
Being slim does not protect you from prediabetes. The ICMR-INDIAB study found it in about 15 in every 100 Indian adults, roughly 136 million people[1], and most people who have it notice no symptoms at all[2].
It is easy to miss for two reasons. Prediabetes symptoms rarely show up, and a person who looks slim can still have excess fat around the organs, which is linked with insulin resistance. This guide explains why weight alone can mislead you, which clues are worth noticing, and which blood test gives a clear answer.
Quick Answer
- Prediabetes symptoms are usually absent[2]. Dark, thickened skin on the neck, armpits, or groin can be a clue to insulin resistance, but it does not confirm prediabetes[6].
- Yes, you can have prediabetes at a normal weight. ICMR notes that Indians tend to carry more body fat and insulin resistance at any given BMI[3].
- India's national NCD programme targets adults aged 30 and above for screening, in line with ICMR guidance[3][4].
- A blood test is the only way to know, and the oral glucose tolerance test can find cases that fasting sugar alone may miss[3].
What Is Prediabetes?
Prediabetes means your blood sugar is higher than normal but not yet in the diabetes range. ICMR describes two forms: impaired fasting glucose, where the morning reading is raised, and impaired glucose tolerance, where sugar stays high after a glucose drink[3]. Some people have both.
The problem underneath is usually insulin resistance. Your body still makes insulin, but the cells respond to it sluggishly, so the pancreas has to work harder to keep sugar in check. It can go on quietly for a long time.
Prediabetes Symptoms: Why Most People Feel Nothing
This is the part most symptom lists leave out. Mayo Clinic states that prediabetes usually has no signs or symptoms at all[2]. The one possible sign it mentions is darker skin in body folds, which we cover below.
That means some popular warning signs do not hold up:
- Sleepiness after a heavy lunch: Common after any big meal, and it says little about blood sugar.
- Sugar cravings: Very common, but not a reliable clinical sign of prediabetes.
- Constant tiredness: It has many causes, including thyroid problems, which our thyroid test normal range chart explains.
More thirst, frequent urination, blurred vision, or weight loss you cannot explain is a different story. Mayo Clinic lists these as signs that sugar may have moved into the type 2 diabetes range[2]. Our guide to the early symptoms of diabetes covers them.
Can You Have Prediabetes at a Normal Weight?
Yes. ICMR describes a pattern called the Asian Indian phenotype. At any given BMI, many Indians carry more total body fat, more fat around the organs, and more insulin resistance than white Caucasian people[3]. The weighing scale cannot see that hidden fat. A tape measure sometimes can.
ICMR also sets a lower bar for Indians. It counts a BMI of 23 or more as overweight for screening, and a waist above 90 cm in men or 80 cm in women as a risk marker[3]. So a BMI that looks fine on a Western chart may already mean higher risk here.
Daily habits add to it. In the ICMR-INDIAB survey of four regions, 54.4% of adults were physically inactive[5]. Muscles that rarely work use less sugar, whatever the number on the scale.
Risk Clues Worth Taking Seriously
None of these proves you have prediabetes. Each one is a good reason to ask for a blood test, and ICMR lists all of them as grounds to screen earlier[3].
Dark, Velvety Skin Patches
Doctors call these patches acanthosis nigricans. They appear on the back of the neck, in the armpits, or in the groin, and they are most often linked to insulin resistance[6]. They do not confirm prediabetes or diabetes. Some medicines can cause them too, so let a doctor take a look before drawing conclusions[6].
Other Clues to Know
- A waist above 90 cm for men or 80 cm for women, even with a normal weight
- A parent, brother, or sister with type 2 diabetes
- Blood pressure of 130/80 or higher
- High triglycerides or low HDL on a cholesterol test
- PCOS, which ICMR lists as a reason to screen early. Our PCOS treatment guide explains how it affects metabolism
- Gestational diabetes in a past pregnancy
- Very little physical activity
Who Should Get Tested?
India's national NCD programme targets adults aged 30 and above for population-based diabetes screening[4], in line with ICMR's 2018 guidelines[3]. With any of the clues above, ICMR advises testing earlier. Under 30 with a strong family history? Our guide to type 2 diabetes in young Indians is written for you.
How often you test depends on the result. ICMR suggests repeating it every three years if normal, and once a year if it shows prediabetes[3].
Which Tests Detect Prediabetes?
Three blood tests are used. Fasting blood sugar is taken after an overnight fast. HbA1c reflects your average sugar over roughly three months, though ICMR notes it has some limitations in India. The oral glucose tolerance test (OGTT) checks sugar before and 2 hours after a 75 g glucose drink[3].
ICMR calls the OGTT the diagnostic test of choice[3]. That matters here, because impaired glucose tolerance only shows up after the glucose drink. You can have a normal fasting reading and still have prediabetes.
| Test | Normal | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting blood sugar | Below 100 (ADA) or below 110 (WHO) | 100 to 125 (ADA) or 110 to 125 (WHO), called impaired fasting glucose | 126 or higher |
| 2 hours after 75 g glucose (OGTT) | Below 140 | 140 to 199, called impaired glucose tolerance | 200 or higher |
| HbA1c | Below 5.7% | 5.7% to 6.4% | 6.5% or higher |
Glucose values in mg/dL, HbA1c in percent. Thresholds differ between guidelines. Source: ICMR Guidelines 2018, Table 3.1, which lists both WHO and ADA values[3].
Why two fasting numbers? WHO and the American Diabetes Association use different cut-offs for impaired fasting glucose, and ICMR's guidance shows both[3]. A result in the diabetes range should be confirmed with a repeat test on another day, unless sugar is clearly very high[3]. For more detail, see our normal blood sugar levels chart by age and our HbA1c normal range chart.
How an OGTT Can Detect Prediabetes That Fasting Glucose May Miss
What to Do If You Have Prediabetes
Start with the encouraging part, backed by Indian data. In the Indian Diabetes Prevention Programme, people with impaired glucose tolerance who made steady lifestyle changes cut their risk of diabetes by 28.5% over three years[7]. By the end, 55% of the control group had developed diabetes, against 39% of the lifestyle group[7].
That is a real benefit, not a guarantee. ICMR says diabetes can be prevented in up to a third of people with prediabetes[3], and Mayo Clinic notes lifestyle change can bring blood sugar back to normal for some[2].
- Move every day: Participants in the Indian trial were advised to walk for about 30 minutes daily[7].
- Eat for steadier sugar: Cut back on refined carbohydrates and sugar, and add more fibre[7]. If you also have PCOS, our Indian PCOS diet chart is a practical start.
- Retest every year so you can see whether things are moving in the right direction[3].
- Leave medicine to your doctor: ICMR says metformin may be considered alongside lifestyle for people likely to progress quickly, especially with both impaired fasting glucose and impaired glucose tolerance[3]. Never start it on your own.
For realistic timelines, read our guide on how long it takes to reverse prediabetes.
When to See a Doctor Sooner
Do Not Wait for a Routine Check If
- You notice more thirst, frequent urination, blurred vision, or weight loss you cannot explain. Arrange a blood sugar test promptly and speak with a doctor[2].
- Very high sugar comes with vomiting, breathlessness, or confusion. Call 112 or 108, or go to the nearest hospital. ICMR describes these as signs of a hyperglycaemic emergency[3].
Key Takeaways
- A normal weight does not mean normal blood sugar, especially for Indians.
- Prediabetes symptoms are rare, so a blood test is what finds it.
- A large waist, family history, PCOS, or dark neck patches are reasons to test early.
- An OGTT can find prediabetes that a fasting test may miss.
- Steady lifestyle change lowers diabetes risk, and yearly testing keeps you on track.
Frequently Asked Questions
What are the symptoms of prediabetes?
Usually there are none. Dark, thickened skin on the neck, armpits, or groin can be a clue to insulin resistance, but it does not confirm prediabetes. Thirst, frequent urination, blurred vision, or unexplained weight loss suggest sugar may already be in the diabetes range.
Can you have prediabetes at a normal weight?
Yes, it happens. ICMR notes that many Indians carry more body fat, more fat around the organs, and more insulin resistance at the same BMI as white Caucasian people. A normal weight lowers risk but does not rule prediabetes out.
Why can Indians with a normal weight develop prediabetes?
Hidden fat around the organs, family history, and low physical activity all play a part. In the ICMR-INDIAB survey of four regions, more than half of adults were physically inactive, and inactivity can raise insulin resistance at any weight.
Is dark skin on the neck a sign of prediabetes?
It can be a clue. Dark, velvety patches called acanthosis nigricans are most often linked to insulin resistance. They do not confirm prediabetes, and some medicines cause them, so ask a doctor about a blood test.
Which test is best to detect prediabetes?
ICMR names the oral glucose tolerance test as the diagnostic test of choice, because it can pick up impaired glucose tolerance that a fasting test may miss. Fasting sugar and HbA1c are also used, though HbA1c has some limitations in India.
At what age should Indians get tested for prediabetes?
From age 30, according to India's national NCD programme and ICMR, and earlier if you have risk factors. If the result is normal, repeat it every three years. With prediabetes, test once a year.
Can prediabetes go back to normal?
For some people, yes. Mayo Clinic notes lifestyle change can bring blood sugar back to normal, and in the Indian Diabetes Prevention Programme it cut diabetes risk by 28.5% over three years. Results vary, so keep testing.
Do people with prediabetes need medicine?
Most start with lifestyle changes alone. ICMR says metformin may be considered for people likely to progress quickly, especially with both impaired fasting glucose and impaired glucose tolerance. That decision belongs to your doctor.
References
- ICMR-INDIAB-17 Study, Lancet Diabetes and Endocrinology, 2023
- Mayo Clinic: Prediabetes Symptoms and Causes
- ICMR Guidelines for Type 2 Diabetes, 2018
- MoHFW: NP-NCD Screening Update, March 2025
- ICMR-INDIAB-5: Physical Activity in India, 2014
- DermNet: Acanthosis Nigricans
- Indian Diabetes Prevention Programme (IDPP-1), Diabetologia, 2006
About the Author
Iraphan Khan, BSN, D.Pharm, is the founder of RealMedVision. He writes evidence-based health guides for patients and families in India, drawing on hospital experience and sources such as ICMR, WHO, and NHS.
Medically Reviewed By
Dr Praveen Verma, MBBS, MD (Pathology), Pathologist and Clinical Laboratory Specialist
Dr Himanshu Morya, MBBS, Medical Educator
Review date: 11 September 2026
Medical disclaimer: This article is for general education and does not replace advice from your own doctor. It does not diagnose or treat any condition. If you are worried about your blood sugar, please get tested and speak with a qualified doctor. In an emergency, call 112 or go to the nearest hospital.