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Signs of diabetes: symptoms, blood sugar levels and when to act

Being thirsty all the time, peeing more and feeling worn out can all point to diabetes. Many people have no signs at all. Here’s what to look for and what your numbers mean.

By the Nourish & Strong team7 min read
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The short answer: the most common signs of diabetes are feeling very thirsty, peeing more than usual, feeling very tired and blurred vision. Many people with type 2 diabetes have no signs at all, so a blood test is the only way to know. A healthy result is an A1C below 5.7% or a fasting blood sugar of 99 mg/dL or below.

Diabetes is common and often missed. About 38.4 million people in the US had it in 2021, and nearly 1 in 4 adults who had it didn’t know.

What are the signs of diabetes?

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the NHS and the CDC list these signs across the main types:

  • Feeling very thirsty
  • Peeing more often than usual
  • Feeling very hungry, even after you’ve eaten
  • Feeling very tired
  • Blurred vision
  • Losing weight without trying
  • Sores that don’t heal
  • Frequent infections, such as urinary tract, skin or yeast infections
  • Feeling irritable or moody

Type 2 can also show up as numbness or tingling in your hands or feet, or dark patches of skin around your neck, armpits or groin.

Tiredness on its own has plenty of other causes, so see why you might always be tired. Thirst has other causes too, including simply not drinking enough water. It’s the combination, especially thirst with lots of trips to the bathroom, that’s worth getting checked.

The NHS advises an urgent appointment for any symptoms of diabetes, in adults or children, so call your doctor promptly.

How do type 1 and type 2 symptoms differ?

The main difference is speed. Type 1 symptoms usually develop quickly, over a few days or weeks. It’s often diagnosed in children and young adults, but it can begin at any age. In children, unexplained bed-wetting can be a sign. Type 1 can’t be prevented.

Type 2 is the most common form, and its symptoms can develop slowly over several years. They can be so mild that you don’t notice them. Gestational diabetes, which develops during pregnancy, usually has no symptoms, and most pregnant women are tested for it.

Can you have diabetes without knowing?

Yes, and many people do. NIDDK estimates 8.7 million US adults had undiagnosed diabetes in 2021. Some people only find out when they develop another problem it caused, such as vision loss, chest pain or tingling feet.

That’s why testing matters even when you feel fine. NIDDK says experts recommend routine testing if any of these apply to you:

  • You’re 35 or older
  • You’re American Indian, Black or African American, Asian American, Hispanic or Latino, or Pacific Islander
  • You have overweight or obesity plus at least one other risk factor
  • You’ve had gestational diabetes

Normal results should be repeated every 3 years. If you have prediabetes, get tested every year.

What is a healthy blood sugar level?

For an adult who isn’t pregnant, a healthy result is an A1C below 5.7% or a fasting blood sugar of 99 mg/dL or below. A1C shows your average over about 3 months. Fasting glucose shows a single moment, after at least 8 hours without food or drink apart from sips of water.

ResultA1CFasting glucose2-hour glucose tolerance testRandom glucose (with symptoms)
NormalBelow 5.7%99 mg/dL or below139 mg/dL or belowNot used
Prediabetes5.7% to 6.4%100 to 125 mg/dL140 to 199 mg/dLNot used
Diabetes6.5% or above126 mg/dL or above200 mg/dL or above200 mg/dL or above

These are the American Diabetes Association cutoffs published by NIDDK. Pregnancy uses different ones. Doctors usually confirm diabetes with a second test, because one high result doesn’t always mean you have it. Cleveland Clinic notes that illness, certain medicines such as steroids, and anemia can throw a result off.

If you already have diabetes, your targets are different. NIDDK gives these common ones, and your care team may set others:

  • Before a meal: 80 to 130 mg/dL
  • About 2 hours after a meal starts: less than 180 mg/dL

How can you tell if you have diabetes at home?

You can’t. NIDDK says plainly not to try to diagnose yourself, and that a store-bought glucose meter can’t diagnose diabetes. If you’re worried, ask your doctor for a blood test. The A1C test needs no fasting, so you can eat and drink beforehand. The American Diabetes Association has an online risk test if you want a starting point.

What is prediabetes, and can it be reversed?

Prediabetes means your blood sugar is above normal but below the diabetes line. About 97.6 million US adults had it in 2021, which is more than 1 in 3, and it usually has no symptoms.

It’s a warning, and you have time to act on it. NIDDK says people with prediabetes have a high chance of developing type 2 within 5 to 10 years, but not everyone does, and healthy living may help prevent or reverse it. Prediabetes can also come with high blood pressure and high cholesterol, so ask to have those checked too.

What lowers your risk of type 2 diabetes?

The best evidence comes from the Diabetes Prevention Program, a trial of 3,234 people at high risk. Over about 3 years, an intensive lifestyle program lowered the chance of developing type 2 by 58% compared with placebo. Its goals were healthier eating, 150 minutes of activity a week and a 7% weight loss. The medicine metformin lowered it by 31%. Nothing here guarantees you won’t get diabetes, but you can start on these today:

  • Move most days. NIDDK suggests at least 30 minutes, 5 days a week. In large Harvard studies, a brisk half-hour walk each day was linked with about 30% lower risk.
  • Swap sugary drinks. Choose water, coffee or tea. Harvard links each extra 12-ounce sugary drink a day with 25% higher risk.
  • Choose whole grains. Their bran and fiber slow digestion, which means slower rises in blood sugar. Our high-fiber foods list makes this easy.
  • Don’t smoke. Harvard says smokers are roughly 50% more likely to develop diabetes.
  • Sleep enough. NIDDK includes this in its advice for prediabetes.
  • Ask about your own risk. Your doctor can tell you whether your weight or a medicine plays a part. The National Diabetes Prevention Program also runs lifestyle change programs.

When is diabetes an emergency?

Diabetic ketoacidosis (DKA) is life threatening, and it’s sometimes the first sign of type 1. It happens when a lack of insulin lets ketones build up in your blood. Symptoms can develop within 24 hours. Call 911, your local emergency number, or go to the ER if you have:

  • Fruity-smelling breath
  • Deep or fast breathing
  • Nausea, vomiting or stomach pain
  • Feeling very tired, sleepy or confused
  • Fainting

Severe low blood sugar mostly affects people who take insulin or some other diabetes medicines. Low means below 70 mg/dL, and severe means below 54 mg/dL. Early signs include shaking, sweating, hunger, a fast heartbeat and confusion.

If you’re awake and your level is low, NIDDK says to take 15 to 20 grams of fast sugar, such as 4 glucose tablets or half a cup of regular fruit juice. Skip orange juice if you have kidney disease. Check again after 15 minutes and repeat if it’s still low.

Call 911 or your local emergency number if someone has a seizure, passes out or can’t treat themselves. Give glucagon if they have it and you know how to use it. Don’t give an unconscious person food or drink, because they can’t swallow safely.

If you’d like a week of meals already decided, take a look at our free 7-day meal plan. If you have diabetes, check any new eating plan with your care team first.

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Quick questions

What is a healthy blood sugar level in the morning?

A healthy fasting blood sugar is 99 mg/dL or below for an adult without diabetes. That’s measured after at least 8 hours without food. A reading of 100 to 125 mg/dL suggests prediabetes, and 126 mg/dL or above suggests diabetes, usually confirmed with a second test.

What is a normal blood sugar level after eating?

For people with diabetes, NIDDK’s common target is under 180 mg/dL about 2 hours after a meal starts. For diagnosis, doctors use a set glucose drink instead of a meal, and 139 mg/dL or below two hours later is normal. Your doctor can explain your own readings.

Is prediabetes the same as diabetes?

No. Prediabetes means your blood sugar is higher than normal but not high enough for a diabetes diagnosis. It raises your chance of type 2 diabetes, though not everyone with it goes on to develop the disease. Test results of 5.7% to 6.4% A1C fall in this range.

Can you have diabetes without symptoms?

Yes. Many people with type 2 diabetes have no symptoms, or symptoms so mild they go unnoticed. Gestational diabetes and prediabetes usually have none either. NIDDK estimates 8.7 million US adults had undiagnosed diabetes in 2021, which is why routine blood tests matter if you have risk factors.

Does diabetes make you tired?

It can. Fatigue is one of the common symptoms listed by NIDDK, and the NHS lists feeling very tired among the main signs. Insulin helps your body use glucose for energy. Tiredness has many other causes, so ask your doctor for a blood test if it lasts.

Can you have diabetes without being overweight?

Yes. Type 1 happens when the immune system destroys the cells that make insulin. Weight is one risk factor for type 2, alongside family history, ethnicity, inactivity, smoking and a history of gestational diabetes, so testing can matter at any size.

This article is general information, not medical advice. If you have symptoms, take diabetes medicine or are pregnant, talk with your doctor.

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