The early symptoms of diabetes are easy to miss: a little more thirst, a few extra trips to the toilet at night, feeling tired after meals. Many people have no symptoms at all for years. That matters in India, where the ICMR-INDIAB study estimated that about 101 million adults have diabetes and another 136 million have prediabetes. This guide covers the warning signs of high blood sugar, the signs of low blood sugar, which tests confirm diabetes, and when to get help.
Quick answer: The classic signs of high blood sugar are excessive thirst, frequent urination, unexplained weight loss, tiredness, blurred vision, slow-healing wounds and repeated infections. Diabetes is confirmed by a blood test: fasting glucose of 126 mg/dL or more, HbA1c of 6.5% or more, or a 2-hour glucose tolerance result of 200 mg/dL or more. Low blood sugar (below 70 mg/dL) causes shaking, sweating, hunger and confusion, and needs quick sugar straight away.
Key takeaways
- ✅ No symptoms does not mean no diabetes. Adults over 30 in India should be screened.
- ✅ Type 1 diabetes often starts suddenly; type 2 creeps up slowly.
- ✅ Vomiting, deep fast breathing or drowsiness with high sugar is an emergency.
- ✅ Caught early, prediabetes can often be reversed with diet, activity and weight loss.
Early warning signs of high blood sugar
- Frequent urination, especially at night, as the kidneys try to flush out extra sugar
- Excessive thirst and a dry mouth
- Constant hunger, even soon after eating
- Unexplained weight loss, more typical of type 1 but also seen in type 2
- Tiredness and weakness
- Blurred vision that comes and goes
- Slow-healing cuts and sores, and frequent skin, gum or urinary infections
- Itching and fungal infections in the groin or genital area
- Tingling, burning or numbness in the feet or hands
- Dark, velvety skin patches on the neck or armpits (acanthosis nigricans), a sign of insulin resistance
Type 1 vs type 2 diabetes symptoms
|
Type 1 |
Type 2 |
| Usual age | Children and young adults, but can occur at any age | Adults, increasingly young adults and teenagers in India |
| Onset | Sudden, over days to weeks | Gradual, over months to years; often found on a routine test |
| Typical signs | Marked thirst, bed-wetting, rapid weight loss, vomiting | Tiredness, infections, slow healing, or no symptoms |
| Cause | The immune system destroys insulin-making cells | Insulin resistance plus reduced insulin, linked to family history, belly fat and inactivity |
| Treatment | Insulin is essential from the start | Lifestyle changes and tablets first; insulin if needed |
Diabetes symptoms in children
Watch for a child who is suddenly always thirsty, starts wetting the bed again after being dry, loses weight despite eating well, is unusually tired or irritable, or has repeated vomiting and tummy pain. These can be signs of type 1 diabetes. Get a blood sugar test the same day, because children can develop diabetic ketoacidosis quickly.
Diabetes in pregnancy (gestational diabetes)
Gestational diabetes usually causes no symptoms, which is why every pregnant woman in India is advised a glucose test. The national programme uses a single test: a 75 g glucose drink with a blood sugar check two hours later, whether or not you have eaten, where a value of 140 mg/dL or more is treated as gestational diabetes. Good control protects both mother and baby, and the mother should be checked again after delivery because her future risk of type 2 diabetes is higher.
Tests that confirm diabetes
| Test |
Normal |
Prediabetes |
Diabetes |
| Fasting plasma glucose (8 hours without food) | Below 100 mg/dL | 100 to 125 mg/dL | 126 mg/dL or more |
| HbA1c (3-month average) | Below 5.7% | 5.7 to 6.4% | 6.5% or more |
| 2-hour OGTT (after 75 g glucose) | Below 140 mg/dL | 140 to 199 mg/dL | 200 mg/dL or more |
| Random glucose with classic symptoms | — | — | 200 mg/dL or more |
Unless there are clear symptoms, a result in the diabetes range is usually repeated to confirm it. A home glucometer reading is useful for monitoring but is not used on its own to diagnose diabetes. For more on meters, CGMs and target ranges, see our complete guide to glucose monitoring.
Signs of low blood sugar (hypoglycemia)
Low blood sugar mostly affects people taking insulin or certain diabetes tablets (such as sulfonylureas), especially after a missed meal, extra exercise or alcohol. A reading below 70 mg/dL is low; below 54 mg/dL is significantly low.
- Shaking, sweating and a fast heartbeat
- Sudden hunger, anxiety or irritability
- Dizziness, headache, blurred vision
- Confusion, unusual behaviour or slurred speech
- At night: nightmares, sweaty sheets, or a morning headache
The 15–15 rule
If sugar is below 70 mg/dL and the person is awake and can swallow, give 15 g of fast sugar: 3 to 4 glucose tablets, half a glass (150 ml) of fruit juice or regular soft drink, or 1 tablespoon of sugar or honey. Recheck after 15 minutes and repeat if still low. Once it is above 70, eat a snack or the next meal. If the person is drowsy, unconscious or having a fit, do not put anything in their mouth. Call an ambulance (108).
When high blood sugar is an emergency
Go to hospital immediately if high sugar comes with:
- Vomiting, tummy pain or being unable to keep fluids down
- Deep, fast breathing or a fruity smell on the breath
- Severe dehydration, drowsiness or confusion
- Readings that stay above 300 mg/dL despite your usual treatment
These can be signs of diabetic ketoacidosis (DKA) or a hyperosmolar state, both of which need urgent treatment.
Long-term warning signs: feet, eyes and kidneys
- Feet: numbness, burning, cracks, blisters, colour change or a wound that will not heal. Check your feet daily and never walk barefoot. Any foot ulcer needs prompt medical care.
- Eyes: diabetic eye disease is often silent at first, so have a dilated eye check every year.
- Kidneys: swelling of the feet or face and foamy urine can be late signs. A yearly urine albumin test and creatinine catch problems early.
Not the same thing: diabetes insipidus
Diabetes insipidus also causes large amounts of urine and extreme thirst, but blood sugar is normal. It is a rare hormone or kidney problem involving vasopressin (ADH), and is diagnosed with urine and blood concentration tests. If you pass very large volumes of pale urine and your sugar tests are normal, ask your doctor about it.
Who should get tested
- All adults aged 30 and above, as advised under India's national screening programme
- Anyone with a parent or sibling with diabetes, excess weight around the waist, high blood pressure or high cholesterol
- Women with past gestational diabetes or PCOS
- Anyone with the symptoms listed above
If your test shows prediabetes, our 7-day Indian meal plan for prediabetes is a practical place to start.
Frequently asked questions
Can you have diabetes without any symptoms?
Yes. Many people with type 2 diabetes feel completely well for years. That is why regular screening matters.
What blood sugar level is dangerous?
Below 70 mg/dL needs treatment straight away, and below 54 mg/dL is significantly low. Persistently above 250 to 300 mg/dL, especially with vomiting or drowsiness, needs urgent medical advice.
Can prediabetes go back to normal?
Often, yes. Losing 5 to 7% of body weight, walking about 150 minutes a week and cutting sugary drinks and refined carbohydrates can bring sugar back to the normal range for many people.
Which foods should people with diabetes limit?
Sugary drinks, sweets, fruit juices, white bread, maida products, large portions of white rice, fried snacks and processed foods. Choose whole grains, dals, vegetables, and protein at every meal.
Last updated: September 2026. General health information only, not a diagnosis or a treatment plan. Please discuss your test results and any change to your medicines with a qualified doctor.
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