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Prediabetes Symptoms: Why Most People Have None, and the Signs Worth Noticing

About 8 in 10 people with prediabetes don't know it, because it rarely causes symptoms. Dr. Sayantan Banerjee explains the subtle signs, who should be tested, and when to see a doctor.

PREDIABETES REMISSION

Dr. Sayantan Banerjee

10/31/20267 min read

One of the most common questions about prediabetes is what it feels like. The honest answer is that, for most people, it doesn't feel like anything. That is exactly why so many people have it without knowing. The CDC estimates that about 8 in 10 Americans with prediabetes are unaware of it. In the UK, Diabetes UK estimates that almost 1.3 million people are living with undiagnosed type 2 diabetes, many of whom will have passed through years of unrecognised prediabetes first.

This article explains why prediabetes is usually silent, which physical signs can be clues, which symptoms suggest glucose has already risen into the diabetes range, and who should get tested even if they feel perfectly well.

Why prediabetes usually has no symptoms

The classic symptoms of diabetes, such as intense thirst and frequent urination, happen when glucose rises high enough to spill into the urine. For most people, that threshold is around 180 mg/dL (10 mmol/L). The kidneys then pull water out with the glucose, causing dehydration and thirst.

In prediabetes, glucose is raised, but usually not that high. Fasting glucose may be 100 to 125 mg/dL (5.6 to 6.9 mmol/L), and A1C 5.7% to 6.4% (39 to 47 mmol/mol). At these levels, the kidneys hold on to glucose, and the body doesn't produce obvious warning signs.

Meanwhile, what is happening under the surface, insulin resistance in the liver and muscles, a pancreas working harder to compensate, and often fat building up in the liver, produces no pain or discomfort. You can have it for years without any clue except a blood test.

Physical signs that can be clues

Some people do have visible or physical signs linked to insulin resistance. These aren't diagnostic on their own, and many people with prediabetes have none of them. But they are worth noticing.

Darkened, velvety skin. A condition called acanthosis nigricans causes patches of darker, thicker, velvety skin, usually on the back of the neck, in the armpits or groin, or over the knuckles. It is strongly linked to high insulin levels and insulin resistance. It is more common in people with darker skin and in people with obesity. If you notice it, ask your doctor about a glucose test.

Skin tags. Small, soft, flesh-coloured growths on the neck, armpits or eyelids are very common in the general population. But having many of them has been linked to insulin resistance in some studies.

A growing waist. Weight gain around the middle, particularly a waist more than half your height, is a strong sign of excess visceral fat, which drives insulin resistance.

Tiredness or sleepiness after meals. Some people notice energy dips after large, carbohydrate-heavy meals. This is common and not specific to prediabetes, but it may reflect larger glucose swings.

Increased hunger soon after eating, especially after refined carbohydrates. This is also non-specific, but sometimes reflects glucose rising fast and then falling.

Conditions that often travel with prediabetes

Some health conditions share the same underlying insulin resistance. If you have one of them, it is a good reason to check your glucose:

high blood pressure
high triglycerides or low HDL cholesterol
fatty liver disease, now called MASLD
polycystic ovary syndrome (PCOS)
obstructive sleep apnoea
a history of gestational diabetes
heart disease or stroke
gout

In women with PCOS, irregular periods, excess hair growth, acne and difficulty losing weight are often linked to insulin resistance. Many women with PCOS develop prediabetes or type 2 diabetes, sometimes at a young age.

Reactive hypoglycaemia

Some people with insulin resistance experience shakiness, sweating, anxiety, a racing heart or intense hunger two to four hours after a meal high in refined carbohydrates. This can be caused by a delayed but excessive release of insulin, which pushes glucose down quickly. It is sometimes called reactive or postprandial hypoglycaemia.

If you get these symptoms, it is worth discussing with your doctor. Eating balanced meals with protein, fibre and fewer refined carbohydrates often helps. Symptoms like these can also have other causes, so don't assume.

Symptoms that suggest diabetes, not just prediabetes

If glucose has risen into the diabetes range, symptoms are more likely. The NHS and CDC list:

feeling very thirsty
passing urine more often than usual, especially at night
feeling very tired
losing weight without trying
blurred vision
itching around the genitals, or repeated thrush (yeast infections)
cuts or wounds that heal slowly
numbness or tingling in the hands or feet
frequent infections, such as urinary or skin infections

If you have several of these, see your doctor soon for a blood test. If you are very unwell, vomiting, breathing fast, confused or very drowsy, seek urgent medical help, as these can be signs of a dangerous rise in glucose or ketones.

Who should be tested

Because prediabetes is usually silent, testing is based on risk rather than symptoms.

In the US, the US Preventive Services Task Force recommends screening adults aged 35 to 70 who have overweight or obesity. The American Diabetes Association recommends testing all adults from age 35, and earlier for people with overweight or obesity plus at least one other risk factor, such as a family history of diabetes, high-risk ethnicity, high blood pressure, abnormal cholesterol, PCOS, physical inactivity or a history of heart disease. Women who had gestational diabetes should be tested at least every three years for life.

In England, the NHS Health Check, offered every five years to adults aged 40 to 74 without certain existing conditions, includes an assessment of diabetes risk and may include a blood test. GPs also test people at higher risk. Diabetes UK offers an online Know Your Risk tool, and the CDC has a one-minute prediabetes risk test on its website.

If your result is normal, the ADA suggests retesting at least every three years. If you have prediabetes, test at least once a year.

Prediabetes in younger people

Prediabetes isn't only a condition of middle age. Rates have risen among young adults and teenagers, especially those with obesity, a family history, or from higher-risk ethnic groups. In children and teenagers, acanthosis nigricans is often the most visible clue. If you are a parent and notice dark, velvety skin on your child's neck, talk to your GP or paediatrician.

Why early detection matters

Finding prediabetes early is valuable because it is one of the most responsive stages of the condition. In the US Diabetes Prevention Program, lifestyle changes cut the risk of type 2 diabetes by 58%. People who returned to normal glucose, even once, had a 56% lower risk of diabetes over the following years.

Prediabetes is also linked to a modestly higher risk of heart disease and stroke, which is another reason to act on it. Knowing your numbers early gives you years in which to change direction.

What to do if you think you might have it

Check your risk using the CDC risk test or Diabetes UK's Know Your Risk tool.
Measure your waist. A waist more than half your height is a warning sign.
Ask your doctor for an A1C or fasting glucose test, especially if you have risk factors or any of the clues above.
If you have prediabetes, ask about a prevention programme, such as the CDC National Diabetes Prevention Program in the US or Healthier You in England.
Start with one change: a short walk after meals, cutting sugary drinks, or adding vegetables and beans to your meals.

Do home glucose tests help?

Finger-prick glucose meters and continuous glucose monitors are increasingly available to the public. They can be interesting and motivating, and some people use them to see how foods affect them. But they aren't a substitute for a proper diagnostic test. A single high reading after a meal doesn't mean you have prediabetes, and a normal fasting reading doesn't rule it out. If you are concerned, ask for an A1C test.

Checking your own risk

Because there are usually no symptoms, risk scores are one of the best ways to decide whether to get tested.

The prediabetes risk test used by the CDC and the American Diabetes Association asks seven simple questions:

How old are you?
Are you a man or a woman?
If you are a woman, have you ever had gestational diabetes?
Do you have a mother, father, sister or brother with diabetes?
Have you ever been diagnosed with high blood pressure?
Are you physically active?
What is your weight category, based on your height and weight?

Each answer adds points. A high score suggests you should be tested. The whole test takes about a minute.

In the UK, Diabetes UK's Know Your Risk tool asks about age, sex, ethnicity, family history, waist size, BMI and blood pressure. It was developed with the University of Leicester and is designed for UK populations, including people of South Asian and Black African and Caribbean heritage, who are at higher risk at lower weights.

Neither tool diagnoses prediabetes. They tell you whether a blood test is worthwhile.

Why so many people are missed

Several factors explain why most people with prediabetes don't know they have it. There are no symptoms to prompt a visit. Routine blood tests don't always include A1C or fasting glucose. Results just above the cut-off may not be discussed. Different cut-offs in the US and UK mean a result can be called normal in one system and prediabetes in another. And many younger adults rarely see a doctor at all.

If you have risk factors, don't wait to be offered a test. Ask for one. If you have had a test, ask for the actual number, not just whether it was normal.

What a diagnosis can feel like

Being told you have prediabetes can be unsettling, especially when you feel well. Some people feel anxious, others feel blamed, and some feel it isn't serious enough to bother with. All of these reactions are understandable. It may help to see the result as early information, given at the point where you have the most control over what happens next.

How my book can help

The Prediabetes Exit Strategy explains insulin resistance and the early metabolic changes behind prediabetes in plain language, and sets out practical steps across food, movement, sleep and daily habits. It is written for people who want to act early, before diabetes develops. More on the book page.

Frequently asked questions

What are the first signs of prediabetes? Usually there are none. Some people notice darkened skin on the neck or armpits, a growing waist, or tiredness after meals.

Can prediabetes make you tired? It can contribute, but tiredness has many causes. If you are persistently tired, see your doctor.

Does prediabetes cause frequent urination? Usually not. Frequent urination and thirst suggest glucose may be in the diabetes range.

Can prediabetes cause weight gain? Insulin resistance and prediabetes are linked to weight gain, especially around the waist, and weight gain worsens insulin resistance.

Can I have prediabetes with a normal weight? Yes, especially with a family history, inactivity, or more fat around the waist.

How do I know for sure? Only a blood test can tell. An A1C or fasting glucose test is the usual first step.

Can prediabetes cause blurred vision? Usually not. Blurred vision is more typical of higher glucose in the diabetes range and should be checked.

Can prediabetes cause tingling in the feet? Some people with prediabetes do develop early nerve changes, but tingling has many causes. See your doctor if you have it.

At what age should I get tested? The ADA recommends testing from age 35, and earlier if you have overweight plus other risk factors. In England, the NHS Health Check starts at 40.