About 12% of the total U.S. population, or 40.1 million people, have diabetes as of 2023. That figure includes both diagnosed and undiagnosed cases. Among adults specifically, the prevalence is higher: 15.8% of U.S. adults have diabetes based on survey and lab data collected between 2021 and 2023.
How Many People Don’t Know They Have It
Roughly one in four American adults with diabetes have never been diagnosed. That translates to about 11 million people walking around with blood sugar levels in the diabetic range who haven’t been told by a doctor. The CDC defines undiagnosed diabetes as having a fasting blood sugar at or above 126 mg/dL, or an A1C of 6.5% or higher, without ever receiving a formal diagnosis.
Among adults, 11.3% have diagnosed diabetes and 4.5% have undiagnosed diabetes. The gap matters because untreated high blood sugar quietly damages blood vessels, nerves, kidneys, and eyes over years. Many people with undiagnosed diabetes only find out after a complication surfaces.
Age Makes a Big Difference
Diabetes prevalence climbs sharply with age. Among adults 65 and older, 28.8% have diabetes, nearly one in three. This steep increase reflects decades of gradual insulin resistance compounded by changes in body composition, physical activity, and how the body processes sugar as it ages. Younger adults have far lower rates, but the overall trend is moving upward across all age groups.
Prediabetes Affects Even More People
Beyond the 40 million with diabetes, another 115.2 million American adults have prediabetes. That’s more than two in five adults. Prediabetes means your blood sugar is elevated but not yet high enough for a diabetes diagnosis, with an A1C between 5.7% and 6.4% (normal is below 5.7%, and diabetes starts at 6.5%).
Most people with prediabetes don’t know they have it either. There are no obvious symptoms. The higher your A1C climbs within that prediabetes range, the greater your risk of progressing to full diabetes. The practical significance of catching prediabetes early is that modest weight loss (5% to 7% of body weight) and regular physical activity can delay or prevent the transition to type 2 diabetes in many cases.
Type 2 Accounts for the Vast Majority
Type 2 diabetes makes up roughly 90% to 95% of all diabetes cases in the U.S. It develops when the body becomes resistant to insulin or doesn’t produce enough of it, typically later in life and often linked to excess weight, inactivity, and genetics. Type 1 diabetes, where the immune system destroys insulin-producing cells, accounts for about 5% to 10% of cases and usually appears in childhood or adolescence, though it can develop at any age.
The Financial Toll
Diabetes cost the U.S. an estimated $412.9 billion in 2022. Of that, $306.6 billion went to direct medical expenses: hospital stays, medications, insulin, doctor visits, and managing complications like kidney disease and amputations. The remaining $106.3 billion came from indirect costs, including missed work, reduced productivity, disability, and premature death. People with diagnosed diabetes spend roughly 2.6 times more on healthcare than they would without the condition.
Where the Numbers Are Headed
Projections from the CDC suggest diabetes prevalence will continue rising for decades. A middle-ground estimate puts the adult prevalence at 25% to 28% by 2050. If diabetes incidence keeps climbing at recent rates and mortality from the disease stays relatively low, prevalence could reach 33% of all U.S. adults. Even the most optimistic scenario, assuming lower incidence and higher diabetes-related mortality, still projects prevalence rising to 21% by 2050.
The driving forces behind these projections are an aging population, rising obesity rates, and the fact that better treatments are keeping people with diabetes alive longer. More new cases each year plus longer survival equals a steadily growing number of Americans living with the disease. Combined with the 115 million adults already in the prediabetes pipeline, the trajectory points clearly upward.