Prediabetes Symptoms: Why Most People Miss Them (and What to Check)

Prediabetes symptoms are easy to miss because, for most people, there are none. About 98 million American adults, more than 1 in 3, have prediabetes, and more than 8 in 10 of them do not know it, according to the CDC. Blood sugar can sit above normal for years without causing anything you can feel. The good news is that prediabetes is common, testable, and often reversible, and one of the largest prevention trials ever run showed how much everyday habits can change the outlook.

This guide covers what prediabetes is, the few signs that can show up, which blood tests confirm it, and what the research says about turning it around.

What Is Prediabetes?

Prediabetes means your blood sugar is higher than normal but not yet high enough to be called type 2 diabetes. It usually develops when the body’s cells respond less well to insulin, the hormone that moves sugar out of the blood and into cells for energy. The pancreas makes more insulin to compensate, and for a while that works. Over time, blood sugar drifts upward.

Prediabetes is best thought of as a signal, not a diagnosis of failure. It tells you that the system that manages fuel in your body is under strain, early enough that you can still respond.

Does Prediabetes Have Symptoms?

Usually, no. That is the main reason it goes undetected. When signs do appear, they are subtle and easy to blame on something else. Possible clues include:

• Darkened, velvety skin on the back of the neck, armpits, elbows or knees. Doctors call this acanthosis nigricans, and it is linked to insulin resistance.
• More thirst or more frequent urination, usually only once blood sugar is climbing toward the diabetes range.
• Tiredness or blurry vision, which have many other causes and are not specific to prediabetes.
• Skin tags, which are common in general but appear more often in people with insulin resistance.

None of these signs can confirm or rule out prediabetes. If you rely on how you feel, you will likely miss it. A simple blood test is the only reliable check.

Who Is Most at Risk for Prediabetes?

Risk rises with age and with weight around the middle, but prediabetes also shows up in people who look healthy. Common risk factors include:

• Age 35 or older
• Overweight, especially extra weight around the waist
• A parent or sibling with type 2 diabetes
• Physical activity fewer than three times a week
• A history of gestational diabetes, or polycystic ovary syndrome
• High blood pressure or abnormal cholesterol

The U.S. Preventive Services Task Force recommends screening adults aged 35 to 70 who have overweight or obesity, and repeating the test about every three years if results are normal (USPSTF, JAMA, 2021). Many clinicians test earlier when other risk factors are present.

Which Tests Diagnose Prediabetes?

Three standard blood tests are used. The American Diabetes Association defines the prediabetes range for each (ADA Standards of Care, 2025):

• A1C: 5.7% to 6.4%. This reflects your average blood sugar over the past two to three months and does not require fasting.
• Fasting plasma glucose: 100 to 125 mg/dL after at least eight hours without food.
• Oral glucose tolerance test: 140 to 199 mg/dL two hours after drinking a standard sugar solution.

Results are usually confirmed with a repeat test. If you have had bloodwork recently, your A1C or fasting glucose may already be in your results. Our guide to the lab numbers worth discussing with a clinician covers how to bring these up at your next visit.

What Happens If Prediabetes Is Not Addressed?

Prediabetes does not always progress, but the risk is real. In a major review in The Lancet, researchers estimated that up to 70% of people with prediabetes eventually develop type 2 diabetes, with roughly 5% to 10% progressing each year depending on the population studied (Tabák et al., The Lancet, 2012). The same review noted that higher blood sugar in the prediabetes range is already associated with early changes in the kidneys, nerves, eyes and blood vessels.

The CDC also lists higher risk of heart disease and stroke. That is why prediabetes is worth taking seriously even though it causes no symptoms today.

Can Prediabetes Be Reversed? What the Research Shows

1. Lifestyle changes cut diabetes risk by more than half

The Diabetes Prevention Program enrolled 3,234 U.S. adults with elevated blood sugar and compared three approaches: an intensive lifestyle program, the drug metformin, or a placebo. The lifestyle group aimed for about 7% weight loss and 150 minutes of moderate activity per week. Over an average of 2.8 years, the lifestyle program reduced new cases of type 2 diabetes by 58% compared with placebo. Metformin reduced them by 31% (Knowler et al., NEJM, 2002). In people aged 60 and older, the lifestyle effect was even larger.

2. The benefit lasted for years

Researchers kept following participants long after the original trial ended. After about 15 years, people from the lifestyle group still had a 27% lower rate of diabetes than the placebo group, and metformin users had an 18% lower rate (DPP Research Group, Lancet Diabetes Endocrinol, 2015). Early action appeared to pay off for a long time.

3. Short movement breaks help blood sugar day to day

You do not need a gym to start. In a randomized crossover trial, adults who took five minutes of light walking every 30 minutes during an eight-hour sitting period had noticeably lower blood sugar after meals than when they sat without breaks (Duran et al., Med Sci Sports Exerc, 2023). Small, frequent movement adds up.

What researchers are exploring next

Most prevention studies measured group averages, so results vary from person to person. Genetics, sleep, stress and medications all influence blood sugar. It is also not yet clear which single change matters most for any one individual. The strongest evidence supports a combination: modest weight loss if needed, regular activity, and a diet built around whole foods and fiber.

5 Simple Steps If You Think You Might Have Prediabetes

• Get tested. Ask your clinician for an A1C or fasting glucose test, especially if you are 35 or older or have any risk factors above.
• Move after meals. A 10 to 15 minute walk after eating is an easy habit, and short breaks from sitting help too.
• Aim for modest weight loss if you carry extra weight. In the Diabetes Prevention Program, the target was about 7% of body weight, not a dramatic transformation.
• Build meals around fiber and protein. Vegetables, beans, whole grains and protein slow how quickly sugar reaches your blood. Our piece on fiber, the quiet tool most plans forget explains why.
• Protect your sleep. Short and irregular sleep are linked with worse blood sugar control. See our guide to sleep schedule consistency.

Not sure where your biggest opportunity is? The free Signal Map quiz helps you see which body systems may need attention first, and our overview of what metabolic health actually means puts blood sugar in context.

Frequently Asked Questions

What are the first signs of prediabetes?

Most people have no signs at all, which is why more than 8 in 10 adults with prediabetes do not know they have it. Some people notice darkened skin on the neck or armpits, and a few have increased thirst or tiredness, but a blood test is the only reliable way to know.

What A1C level is prediabetes?

The American Diabetes Association defines prediabetes as an A1C of 5.7% to 6.4%, a fasting glucose of 100 to 125 mg/dL, or a 2-hour glucose tolerance result of 140 to 199 mg/dL. An A1C of 6.5% or higher is in the diabetes range.

Can prediabetes be reversed?

Many people can bring their blood sugar back into the normal range. In the Diabetes Prevention Program, a lifestyle program built around modest weight loss and about 150 minutes of weekly activity cut the risk of developing type 2 diabetes by 58% over about three years.

Ready to take the next step? The 21-Day Metabolic Friction Reset is a simple, day-by-day plan for movement, meals and sleep habits that support healthier blood sugar. See the program →

Sources

1. Centers for Disease Control and Prevention. National Diabetes Statistics Report and Prediabetes: Could It Be You? CDC; 2023–2024. cdc.gov
2. Knowler WC, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346(6):393-403. doi:10.1056/NEJMoa012512
3. Diabetes Prevention Program Research Group. Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications over 15-year follow-up: the Diabetes Prevention Program Outcomes Study. Lancet Diabetes Endocrinol. 2015;3(11):866-875. doi:10.1016/S2213-8587(15)00291-0
4. Tabák AG, et al. Prediabetes: a high-risk state for diabetes development. Lancet. 2012;379(9833):2279-2290. doi:10.1016/S0140-6736(12)60283-9
5. American Diabetes Association Professional Practice Committee. 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes—2025. Diabetes Care. 2025;48(Suppl 1):S27-S49. doi:10.2337/dc25-S002
6. US Preventive Services Task Force. Screening for prediabetes and type 2 diabetes: recommendation statement. JAMA. 2021;326(8):736-743. doi:10.1001/jama.2021.12531
7. Duran AT, et al. Breaking up prolonged sitting to improve cardiometabolic risk: dose-response analysis of a randomized crossover trial. Med Sci Sports Exerc. 2023;55(5):847-855. doi:10.1249/MSS.0000000000003109

This article is for education only and is not medical advice. Talk with your healthcare professional about testing and before changing your health routine.