About 14% of adults worldwide have diabetes, a rate that has doubled since 1990. In the United States, the numbers are even higher: roughly 15.8% of American adults have diabetes, and more than 1 in 4 of them don’t know it.
Global Diabetes Numbers
More than 800 million adults worldwide are now living with diabetes. Global prevalence in adults rose from 7% in 1990 to 14% in 2022, a fourfold increase in total cases over roughly three decades. Much of that growth is driven by rising rates of type 2 diabetes, which is closely linked to obesity, physical inactivity, and aging populations.
Projections from the International Diabetes Federation estimate that global prevalence among adults aged 20 to 79 will climb from about 10.5% to 12.2% by 2045, potentially affecting more than 783 million people. These projections assume current trends continue without major intervention.
Diabetes Prevalence in the United States
The CDC reports that 40.1 million people in the U.S. have diabetes. That’s about 1 in every 8 Americans. When measured specifically in adults, the prevalence is 15.8%, which breaks down to 11.3% diagnosed and 4.5% undiagnosed. In practical terms, roughly 8.7 million American adults are walking around with blood sugar levels that meet the threshold for diabetes without knowing it.
Men are more likely to have diabetes than women. The age-adjusted rate for men is 16.6%, compared to 12.2% for women. The gap holds for undiagnosed cases too: about 4.9% of men have undiagnosed diabetes versus 3.5% of women.
How Age Affects the Numbers
Diabetes prevalence rises sharply with age. Among Americans 65 and older, 28.8% have diabetes, nearly one in three. This makes sense biologically: as the body ages, its ability to regulate blood sugar declines, and decades of lifestyle factors accumulate. Younger adults have much lower rates, though type 2 diabetes diagnoses in people under 40 have been increasing.
Type 1 vs. Type 2
Type 2 diabetes accounts for about 91% of all diagnosed cases. Type 1 makes up roughly 5.8%, with the remaining fraction consisting of rarer forms like gestational diabetes that persists after pregnancy or diabetes caused by other medical conditions.
Type 1 is an autoimmune condition where the body destroys the cells that produce insulin. It typically appears in childhood or early adulthood and is not preventable. Type 2 develops when the body becomes resistant to insulin or stops producing enough of it, and is strongly influenced by weight, diet, activity level, and genetics. The overwhelming majority of the global increase in diabetes is driven by type 2.
The Undiagnosed Problem
One of the most striking statistics is how many people have diabetes without knowing it. In the U.S., about 22.8% of adults with diabetes are undiagnosed. That means for every four people who know they have it, there’s a fifth person who doesn’t. These individuals aren’t managing their blood sugar, which means years of damage can accumulate in blood vessels, kidneys, nerves, and eyes before they ever get a diagnosis.
Undiagnosed diabetes is identified through blood tests: either a fasting blood sugar level at or above 126 mg/dL, or a hemoglobin A1c of 6.5% or higher in someone who has never been told they have the condition. Because type 2 diabetes can develop slowly and cause few obvious symptoms in its early stages, routine screening is the only reliable way to catch it.
Income and Diabetes Risk
Diabetes does not affect all groups equally. People living below the federal poverty level have a diabetes rate of 13.1%, more than double the 5.1% rate seen in households earning five times the poverty threshold or more. Lower-income communities often face limited access to fresh food, fewer safe places to exercise, and greater barriers to preventive healthcare. These factors compound over time and help explain why diabetes clusters in certain populations.
How Many People Have Prediabetes
Beyond the 40 million Americans with diabetes, a far larger group has prediabetes, meaning their blood sugar is elevated but not yet high enough for a diabetes diagnosis. Estimates put that number at roughly 97 to 98 million U.S. adults, or about 1 in 3. Most people with prediabetes are unaware of it. Without changes to diet and physical activity, roughly 15% to 30% of people with prediabetes will develop type 2 diabetes within five years. The good news is that prediabetes is the stage where lifestyle changes, particularly modest weight loss and regular exercise, are most effective at preventing progression.