About 40.1 million people in the United States have diabetes. That figure includes both those who know they have it and those who don’t, and it represents roughly one in eight American adults. On top of that, 115.2 million adults have prediabetes, a condition where blood sugar is elevated but not yet high enough for a diabetes diagnosis. Taken together, more than half of all American adults are living with diabetes or prediabetes.
Diagnosed vs. Undiagnosed Cases
Of the 40.1 million Americans with diabetes, about 29.1 million have been formally diagnosed. The remaining share, more than 1 in 4 adults with the disease, don’t know they have it. CDC survey data from 2021 to 2023 puts the overall diabetes prevalence at 15.8% of U.S. adults: 11.3% diagnosed and 4.5% undiagnosed.
Undiagnosed diabetes is identified through blood tests showing elevated fasting blood sugar or a high average blood sugar level over the prior two to three months. People in this category have never been told by a doctor that they have diabetes, yet their lab results meet the clinical threshold. Because diabetes can damage blood vessels, nerves, kidneys, and eyes for years before symptoms become obvious, that undiagnosed group faces serious health risks without knowing it.
Type 1 vs. Type 2 Breakdown
Type 2 diabetes accounts for the vast majority of cases. Of the 29.1 million people with a diagnosis, about 2.1 million have type 1 diabetes. That includes roughly 1.8 million adults and 314,000 children and adolescents under 20. Type 1 is an autoimmune condition where the body attacks its own insulin-producing cells, and it typically appears in childhood or young adulthood, though it can develop at any age.
Everyone else with a diagnosis, roughly 27 million people, has type 2 diabetes. In type 2, the body still makes insulin but can’t use it efficiently. It develops gradually, often over years, and is closely linked to weight, physical activity levels, and genetics. This is also the type that makes up nearly all undiagnosed cases, since it can progress silently.
Rising Rates in Children and Teens
Diabetes is increasingly a disease of the young. Between 2002 and 2018, the rate of new type 1 diagnoses in young people rose from 20 to 22 per 100,000 per year. The more striking trend is type 2: new cases in children and adolescents doubled over the same period, jumping from 9 to 18 per 100,000 per year. That increase tracks closely with rising rates of childhood obesity and more sedentary lifestyles.
Where Diabetes Hits Hardest
Diabetes is not evenly distributed across the country. The Southeast has the highest rates by a wide margin. A 2021 analysis found that 14 states, mostly in the Southeast plus Illinois, Oregon, and Pennsylvania, had rural diabetes prevalence of 15.8% or higher. North Carolina’s rural areas topped out at 21.3%, meaning more than one in five adults had the disease. West Virginia led among urban areas at 15.5%.
Colorado had the lowest rates in both rural and urban settings (8.4% and 6.9%, respectively). States in the Mountain West and Upper Midwest, including Montana, Utah, Wyoming, Minnesota, and Iowa, consistently clustered at the low end. Rural areas across all states had higher diabetes rates than urban areas, with a national gap of about 3 percentage points (14.3% vs. 11.2%).
Prediabetes: The Larger Problem
The 115.2 million American adults with prediabetes represent more than 2 in 5 adults, or about 42.6% of the adult population. Prediabetes means your blood sugar is higher than normal but below the diabetes threshold. Without changes to diet, exercise, or weight, roughly 15% to 30% of people with prediabetes will develop type 2 diabetes within five years.
Most people with prediabetes don’t know they have it either. There are no obvious symptoms. It’s typically caught through routine bloodwork, which is why screening recommendations target adults over 35 and anyone with risk factors like excess weight, a family history of diabetes, or a sedentary lifestyle.
The Financial Toll
Diabetes costs the U.S. $413 billion per year, making it the most expensive chronic condition in the country. Of that total, $307 billion goes to direct medical costs: hospitalizations, medications, doctor visits, insulin, and supplies. The remaining $106 billion reflects reduced productivity from disability, missed work, and premature death. People with diabetes spend about 2.3 times more on medical care than people without it.
Projected Growth Through 2050
The numbers are expected to keep climbing. CDC modeling projects that total diabetes prevalence among U.S. adults will rise from about 14% to somewhere between 21% and 33% by 2050, depending on whether new diagnoses continue at their current pace and how mortality trends shift. A middle-ground scenario estimates prevalence of 25% to 28%, meaning roughly one in four American adults could have diabetes by mid-century. Annual new cases are projected to nearly double, from about 8 per 1,000 adults to 15 per 1,000.
These projections reflect both an aging population and the continued rise of obesity, which remains the single strongest modifiable risk factor for type 2 diabetes. They also assume no major breakthroughs in prevention, which makes the prediabetes population a critical intervention point: that group of 115 million adults represents the pipeline feeding future diabetes cases.