How many Americans have a health problem and don’t know it?
Some of the most common health problems cause no symptoms for years. Here’s how many people have them, how many don’t know, and the simple tests that find them.
Tens of millions. 8 in 10 US adults with prediabetes don’t know they have it, and that’s about 92 million people. About 9 in 10 adults with chronic kidney disease don’t know. About 4 in 10 adults with high blood pressure haven’t been told they have it, and 11 million people have diabetes that hasn’t been diagnosed. Most of these can be found with a blood pressure check or a routine blood test.
- Feeling fine doesn’t mean you’re fine. These conditions usually cause no symptoms for years.
- They’re common. Almost half of US adults have high blood pressure, and more than 2 in 5 have prediabetes.
- They’re connected. Diabetes and high blood pressure are the two biggest causes of kidney disease.
- Younger adults miss it most. Nearly 3 in 4 adults under 40 with high blood pressure don’t know they have it.
- They’re easy to find. A blood pressure check and a routine blood test cover almost everything on this page.
Sources: CDC National Diabetes Statistics Report (2026), CDC Chronic Kidney Disease in the United States (2026), NCHS Data Brief No. 511 (2024). Kidney disease awareness is for adults 20 and older.
longevityclinicshub.comPicture a room of 10 adults
Percentages can feel abstract. Here’s what the numbers look like in a room of 10 US adults.
Rounded from CDC figures: high blood pressure 47.7% of adults, prediabetes more than 2 in 5 adults, kidney disease 14% of adults and diabetes 12.0% of people. One person can have more than one condition, so the rows overlap.
longevityclinicshub.comPut another way: chances are someone you know is living with one of these right now, and may not know it yet.
Why so many people don’t know
These conditions have something in common. In the early years, most of them don’t hurt, don’t make you tired and don’t change how you feel. You can feel completely fine while your blood sugar, blood pressure or kidney function slowly drifts in the wrong direction.
It’s like a slow leak in a tire. The car drives fine for weeks, and nothing feels different from the driver’s seat. A tire gauge spots the leak in seconds, long before you’d ever notice it on the road. A blood pressure cuff and a routine blood test are the tire gauge.
Three things people often think
Compare what’s included and what it costs.
The conditions, one by one
Prediabetes
Your blood sugar is higher than normal, but not high enough to be called diabetes yet. It’s common, it’s quiet, and it’s often reversible with changes to diet, activity and weight.
Of every 10 adults with prediabetes, 8 don’t know it (outlined) and 2 do (filled).
It gets more common with age. More than half of adults 65 and older (52.1%, or 31.3 million people) have prediabetes. The CDC says healthy changes, like losing a modest amount of weight and moving more, can cut the risk of type 2 diabetes in half.
Higher risk if you: have overweight or obesity, are 45 or older, have a parent or sibling with type 2 diabetes, are active less than 3 times a week or had diabetes during pregnancy.
Chronic kidney disease
The kidneys slowly lose their ability to filter blood. Early on there’s usually nothing to feel, which is why it’s the least-known condition on this list.
Higher risk if you: have diabetes or high blood pressure (the two biggest causes), have heart disease, have obesity or have family members with kidney disease. About 1 in 5 adults with high blood pressure has kidney disease.
High blood pressure
The force of blood against your artery walls stays too high. Over years it strains the heart, brain, kidneys and eyes. It’s the most common condition on this list.
Gets more common with age: about 23% of adults under 40, 53% of adults 40 to 59 and 72% of adults 60 and older.
Diabetes
Blood sugar stays high enough to damage blood vessels and nerves over time. Most adults with diabetes know it, but a large group still doesn’t.
Higher risk if you: have the same risk factors as prediabetes. Having prediabetes is a major warning sign.
High cholesterol
Too much cholesterol in the blood builds up in artery walls over time. There are no symptoms at all, so the only way to know is a test.
Younger adults are the least likely to know
High blood pressure isn’t just an older person’s problem. Almost 1 in 4 adults under 40 has it, and nearly 3 in 4 of them don’t know.
Source: NCHS Data Brief No. 511. High blood pressure here means 130/80 or higher, or taking blood pressure medicine.
longevityclinicshub.comOne often leads to another
These conditions don’t stay in their own lanes. Catching one early can help you head off the next.
High blood pressure feeds into the same chain. About 1 in 5 adults with high blood pressure already has kidney disease.
When to get checked
Here’s what US screening guidelines say for adults without symptoms. Your doctor may suggest more, based on your history.
| Test | What it finds | How often |
|---|---|---|
| Blood pressure check | High blood pressure | Every year from age 40, or if you’re at higher risk. Every 3 to 5 years from 18 to 39 if your last reading was normal. |
| A1c or fasting glucose | Prediabetes and diabetes | Adults 35 to 70 with overweight or obesity. About every 3 years if normal. |
| Kidney blood and urine tests | Kidney disease | Ask your doctor, especially if you have diabetes or high blood pressure. |
| Lipid panel | High cholesterol | Ask your doctor. Many adults get it with routine blood work. |
Source: US Preventive Services Task Force (blood pressure, 2021; prediabetes and diabetes, 2021). Kidney and cholesterol timing depends on your health, so it’s a conversation with your doctor.
What you can do about it
The good news: every condition on this page can be found with quick, common tests, and most are part of a routine checkup. Start with your regular doctor. A yearly checkup with a blood pressure check and routine blood work catches most of this.
Longevity care can add to that, with a wider blood panel, more frequent tracking and a plan to keep the numbers moving the right way. If you’re curious what that looks like, read biomarker testing vs. your annual physical or see clinics near you.
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LongevityClinicsHub. (2026, October). How many Americans have a health problem and don’t know it? https://longevityclinicshub.com/learn/undiagnosed-health-conditions/ (Data: CDC.) Common questions
How many Americans have prediabetes?
115.2 million US adults, which is more than 2 in 5. 8 in 10 of them don’t know they have it.
What percentage of people with kidney disease don’t know it?
About 9 in 10 (87%) adults 20 and older with chronic kidney disease don’t know they have it, according to the CDC.
How many people have undiagnosed diabetes?
About 11.0 million, or 27.6% of adults with diabetes.
How many adults with high blood pressure don’t know it?
About 4 in 10. In 2021 to 2023, 59.2% of adults with high blood pressure had been told they have it. Among adults under 40, only 27.2% knew.
How often should I get my blood pressure checked?
US guidelines say every year from age 40, or if you’re at higher risk. Adults 18 to 39 with a normal reading can check every 3 to 5 years.
Can you have these conditions without symptoms?
Yes. That’s why they go unnoticed. Prediabetes, early kidney disease, high blood pressure and high cholesterol usually cause no symptoms for years. A blood pressure check and routine blood tests are how they’re found.
Prepared by the LongevityClinicsHub editorial team. How we research and source these guides.
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Sources
- CDC, National Diabetes Statistics Report (Sept 2026).
- CDC, Prediabetes: Could It Be You? (Feb 2026).
- CDC, Chronic Kidney Disease in the United States, 2026.
- NCHS, Hypertension Prevalence, Awareness, Treatment, and Control Among Adults: United States, August 2021 to August 2023. Data Brief No. 511 (Oct 2024).
- NCHS, Total and High-density Lipoprotein Cholesterol in Adults: United States, August 2021 to August 2023. Data Brief No. 515 (Nov 2024).
- CDC, Diabetes risk factors and Chronic kidney disease risk factors.
- US Preventive Services Task Force, Hypertension in Adults: Screening (Apr 2021) and Prediabetes and Type 2 Diabetes: Screening (Aug 2021).
- “About 92 million” is our math: 115.2 million adults with prediabetes times 8 in 10.
This guide is independent editorial content, written to orient, not to diagnose. It is not medical advice, and it is no substitute for a conversation with a licensed physician who knows your history. Where we describe what clinics claim, the claim belongs to the clinic.
Educational reading, not medical advice. Talk to a clinician about your own health.