Prediabetes is remarkably common — and remarkably quiet. According to the CDC, more than 1 in 3 U.S. adults have prediabetes, and roughly 8 in 10 of them don't know it. That's largely because prediabetes often produces no symptoms at all until blood sugar has climbed for years.

Signs That Sometimes Show Up

When symptoms do appear, they tend to be subtle and easy to explain away. Some people notice:

  • Feeling more tired than usual, especially after meals
  • Increased thirst or more frequent urination
  • Patches of darkened skin, often around the neck or armpits (a sign called acanthosis nigricans)
  • Slower-healing cuts or bruises
  • Blurred vision

None of these are exclusive to prediabetes, and many people with prediabetes have zero symptoms whatsoever. That's exactly why it so often goes undetected — it doesn't announce itself.

Who's Most at Risk

Risk climbs with factors like being over 45, carrying extra weight (especially around the midsection), having a family history of type 2 diabetes, low physical activity levels, and a history of gestational diabetes. Some racial and ethnic groups — including Black, Hispanic, American Indian, and Asian American individuals — also carry statistically higher risk according to CDC data.

The Only Way to Really Know

Because symptoms are so unreliable, the CDC and ADA recommend a simple blood test as the only dependable way to check: fasting plasma glucose, A1C, or an oral glucose tolerance test. Prediabetes is generally defined as an A1C between 5.7% and 6.4%, or fasting glucose between 100–125 mg/dL.

The Encouraging Part

Prediabetes is not a diagnosis of inevitability. Research, including the landmark Diabetes Prevention Program study, has repeatedly shown that modest weight loss and regular physical activity can significantly reduce the chance of prediabetes progressing to type 2 diabetes — in some studies cutting the risk by more than half.