Prediabetes Symptoms: The Silent Signs (and What Your Skin Can Reveal)

You heard the word "prediabetes" at a checkup, and now you're scanning your body for warning signs. Here's the hard part: there usually aren't any. Prediabetes is famously quiet, which is exactly why it can go unnoticed for years.

That silence is the real risk. But your body, and especially your skin, can occasionally hint that something is off. Knowing what to look for, and when to simply get tested, is how you catch this early enough to do something about it.

What Are the Symptoms of Prediabetes?

For most people, prediabetes has no clear symptoms at all. Blood sugar is higher than normal but not yet high enough to cause the obvious signs of diabetes, so it can persist for years undetected. According to the CDC, about 8 in 10 adults with prediabetes don't know they have it. In 2021, roughly 97.6 million U.S. adults had prediabetes, a reminder of how common and how hidden this condition is.

When symptoms do show up, they tend to be mild and easy to brush off as stress, aging, or a busy season of life. That's why prediabetes is often called a "silent" condition, and why a simple blood test matters far more than waiting to feel sick.

• Increased thirst
• Frequent urination
• Fatigue or low energy
• Blurred vision
• Cuts and scrapes that heal slowly

The Skin Sign Most People Miss: Acanthosis Nigricans

One of the few visible clues to prediabetes shows up on your skin. It's called acanthosis nigricans: patches of dark, thick, velvety skin that most often appear on the back of the neck, in the armpits, and in the groin. The skin in these folds can look dirty or stained, but it won't wash off.

This is more than a cosmetic quirk. Acanthosis nigricans is a recognized marker of insulin resistance, the underlying process that drives prediabetes. When the body becomes resistant to insulin, blood levels of insulin climb, and that excess insulin can stimulate skin cells to grow and darken in these creased areas. Most people with acanthosis nigricans have become resistant to insulin and are much more likely to develop type 2 diabetes, which makes this skin finding a genuinely useful early warning sign.

If you notice these darker, velvety patches developing in body folds, it's worth mentioning to a clinician and asking about blood sugar testing, especially alongside any other risk factors.

Why Prediabetes Stays Hidden

Prediabetes sits on a spectrum. Your blood glucose has crept above the normal range, but it hasn't reached the threshold where the body floods you with thirst, urination, and weight changes. In that in-between zone, the warning system mostly stays quiet.

Underneath, insulin resistance and stress on the insulin-producing beta cells are slowly building. You can't feel that happening day to day, which is why screening, not symptom-watching, is the reliable way to catch it. If you have risk factors like family history, higher body weight, high blood pressure, or a history of gestational diabetes, testing is the smart move even when you feel completely fine.

How Prediabetes Is Diagnosed

Because you usually can't feel it, prediabetes is diagnosed with a blood test rather than a symptom checklist. Two common measures are the A1C and the fasting blood glucose test.

The A1C reflects your average blood sugar over the prior two to three months, so it smooths out daily ups and downs. Here's how the standard thresholds line up:

• A1C 5.7%–6.4% indicates prediabetes; below 5.7% is normal and 6.5% or higher indicates diabetes
• Fasting blood glucose 100–125 mg/dL indicates prediabetes
• A single result should be confirmed and interpreted by a clinician, not self-diagnosed

Prediabetes vs. Type 2 Diabetes: Why Catching It Early Matters

Prediabetes is not the same as diabetes, and it is not a guarantee that you'll develop it. Roughly one third of people with prediabetes progress to type 2 diabetes over a 5–7 year period, which means the trajectory is far from fixed. Beyond diabetes itself, prediabetes also raises the risk of heart disease and stroke, so it's worth taking seriously.

The encouraging part is how much influence you have. The CDC notes that losing 5%–7% of your body weight and getting at least 150 minutes per week of brisk walking can significantly cut the risk of moving from prediabetes to type 2 diabetes. Small, consistent changes, not perfection, move the needle here.

When to See a Doctor

Because prediabetes is usually symptomless, the most important time to act is before you notice anything at all. Ask a clinician about screening if you have risk factors such as a family history of diabetes, higher body weight, high blood pressure, or you're over 45.

See a doctor promptly if you develop the classic signs of high blood sugar: marked thirst, frequent urination, unexplained fatigue, blurred vision, or slow-healing cuts. And if you notice new dark, velvety patches in your skin folds, bring them up, since they can be an early flag for insulin resistance. A short conversation and a simple blood test are all it takes to know where you stand, and to build a plan that fits your life.