More than 800 million adults worldwide are living with diabetes, a number that has quadrupled since 1990. In the United States alone, 40.1 million people have the condition, roughly 1 in every 8 Americans. These numbers only tell part of the story, though, because millions more have diabetes and don’t know it yet.
Global Numbers at a Glance
The worldwide prevalence of diabetes in adults doubled from 7% to 14% between 1990 and 2022, according to the World Health Organization. That trajectory shows no sign of slowing. Projections from the International Diabetes Federation estimate 783 million adults will have diabetes by 2045.
Diabetes was the direct cause of 1.6 million deaths in 2021, with nearly half of those deaths occurring in people under 70. An additional 530,000 deaths from kidney disease were attributed to diabetes that same year. Globally, about 12% of all health spending goes toward diabetes care, averaging $1,760 per person with the condition each year.
How Many Americans Have Diabetes
The CDC reports that 40.1 million U.S. adults have diabetes. That 1-in-8 figure includes both diagnosed and undiagnosed cases. More than 1 in 4 American adults with diabetes don’t know they have it, meaning they aren’t managing their blood sugar and face a higher risk of complications like nerve damage, vision loss, and heart disease.
Age is the single biggest demographic factor. Among Americans 65 and older, 28.8% have diabetes. That’s nearly three times the rate seen in younger adults, driven largely by decades of gradual insulin resistance that often builds silently in middle age.
The Undiagnosed Problem
Globally, an estimated 252 million adults are living with diabetes and have never been diagnosed. That’s 43% of all people with the condition. Almost 90% of those undiagnosed cases are in low- and middle-income countries, where routine blood sugar screening is less accessible. In wealthier nations, the gap is smaller but still significant. The U.S. figure of more than 1 in 4 going undiagnosed means roughly 10 million Americans are walking around with elevated blood sugar levels that are actively damaging their blood vessels, kidneys, and nerves without their knowledge.
Undiagnosed diabetes is dangerous precisely because the condition can be painless for years. Blood sugar can run high enough to cause internal damage long before symptoms like excessive thirst, frequent urination, or blurred vision become obvious.
Prediabetes: The Larger Hidden Number
The diabetes figures don’t capture the full scope of the problem. In the United States, 115.2 million adults have prediabetes, a condition where blood sugar is elevated but not yet high enough for a diabetes diagnosis. That’s more than a third of American adults.
Prediabetes prevalence climbs steeply with age. Among 18- to 44-year-olds, about 36% have it. That rises to nearly 49% of adults aged 45 to 64, and crosses 52% in adults 65 and older. In other words, more than half of older Americans have blood sugar levels outside the normal range even if they haven’t been diagnosed with full diabetes. The practical significance: prediabetes is the stage where lifestyle changes like increased physical activity and modest weight loss are most effective at preventing progression to type 2 diabetes.
Type 1 vs. Type 2 Breakdown
Type 2 diabetes accounts for 90% to 95% of all diagnosed cases. It develops when the body gradually loses its ability to use insulin effectively, typically over years or decades. Weight, physical activity level, genetics, and age all play a role. Type 1 diabetes makes up the remaining 5% to 10% and is an autoimmune condition where the body destroys the cells that produce insulin. Type 1 usually appears in childhood or adolescence, though it can develop at any age, and it requires insulin from the point of diagnosis.
The distinction matters because the two types have different causes, different trajectories, and different management strategies. The global surge in diabetes is almost entirely driven by type 2, which tracks closely with rising rates of obesity and sedentary lifestyles across the world.
Why the Numbers Keep Rising
The fourfold increase since 1990 reflects several overlapping trends. Diets worldwide have shifted toward processed foods high in refined carbohydrates and added sugars. Physical activity levels have dropped as economies move toward desk-based work. Urbanization in low- and middle-income countries has accelerated both of these changes simultaneously. Population aging also plays a role, since the risk of type 2 diabetes increases with every decade of life.
Better detection partly inflates the numbers as well. More people are being screened and diagnosed than in previous decades, which is a good thing for individual outcomes even though it pushes the headline figures higher. Still, the gap between diagnosed and undiagnosed cases, particularly in developing nations, suggests the true global count may already be higher than current estimates reflect.