About 90% to 95% of all people with diabetes have type 2, making it by far the most common form of the disease. In the United States alone, more than 40 million Americans have diabetes (roughly 1 in 8), and the vast majority fall into the type 2 category. The remaining 5% to 10% is split among type 1 diabetes, gestational diabetes, and rarer forms caused by genetic conditions or other diseases.
How Type 2 Compares to Other Forms
Type 1 diabetes is an autoimmune condition where the body destroys the cells that produce insulin. It typically appears in childhood or adolescence and accounts for about 5% to 10% of all cases. Type 2, by contrast, develops when the body becomes resistant to insulin or stops making enough of it. This process usually unfolds over years in adults, though it is increasingly diagnosed in younger people.
Gestational diabetes occurs during pregnancy and usually resolves after delivery, though it significantly raises the risk of developing type 2 later in life. Other rare forms, sometimes called monogenic diabetes or secondary diabetes, make up a very small fraction of total cases.
Millions of Cases Go Undiagnosed
The 90% to 95% figure only captures people who know they have diabetes. A substantial number of cases remain undetected. CDC data from 2021 to 2023 found that 15.8% of U.S. adults aged 20 and older had diabetes, but only 11.3% had been formally diagnosed. The remaining 4.5% had diabetes without knowing it. Because type 2 can develop slowly and produce mild or no symptoms in its early stages, people can live with elevated blood sugar for years before getting a diagnosis.
On top of that, an estimated 115.2 million U.S. adults have prediabetes, a condition where blood sugar is higher than normal but not yet in the diabetes range. Among adults 65 and older, more than half (52.1%) have prediabetes. Without lifestyle changes, a significant portion of these individuals will progress to type 2.
The Prevalence Has Risen Sharply
Type 2 diabetes is not just the dominant form of diabetes. It’s also growing fast. A large observational analysis tracking U.S. patterns from 1990 to 2024 found that the prevalence of type 2 doubled over that period, climbing from 5.80% to 11.65% of the adult population. The incidence, meaning new cases per year, rose even more dramatically: from 3.52 per 1,000 people in the early 1990s to 59.30 per 1,000 by the early 2020s.
Rising obesity rates, sedentary lifestyles, and an aging population are the primary drivers. But the trend is also showing up in younger people. In the U.S., the rate of new type 2 diagnoses among children and adolescents nearly doubled between 2002 and 2018, going from 9.0 to 17.9 cases per 100,000 per year. Germany saw a threefold increase in 10- to 19-year-olds over a similar period. The COVID-19 pandemic appears to have accelerated this: one U.S. study across 24 diabetes centers found a 77% jump in new youth diagnoses during the first pandemic year compared to the two years prior.
Racial and Ethnic Disparities
Type 2 diabetes does not affect all populations equally. In the U.S., the prevalence of diagnosed type 2 diabetes among non-Hispanic white adults is about 7.6%. Among Asian Americans, it’s 9.0%. Among Hispanic Americans, 12.8%. Among African Americans, 13.2%. These gaps reflect a combination of genetic susceptibility, differences in access to healthcare, dietary patterns, and socioeconomic factors.
Some of the widest variation exists within broader ethnic categories. Among Native American populations, rates range from 6.0% in Alaskan Natives to 24.1% in certain southern Arizona groups. Among Hispanic subgroups, Central and South Americans have a prevalence of about 8.5%, while Puerto Ricans are at 14.8%. These differences matter because national averages can obscure the reality that certain communities carry a far heavier burden of the disease.
Why Type 2 Dominates the Numbers
The reason type 2 accounts for such an overwhelming share of diabetes comes down to its causes. Type 1 requires a specific autoimmune trigger that affects a relatively small number of people. Type 2, on the other hand, is driven by factors that are widespread across modern populations: excess body weight, physical inactivity, poor diet quality, and aging. Insulin resistance tends to build gradually, and the pancreas compensates for a while before it can no longer keep up. This means the pool of people at risk for type 2 is enormous, and it keeps growing as obesity rates climb and populations age.
Genetics play a role too. Having a parent or sibling with type 2 diabetes roughly doubles or triples your own risk. But unlike type 1, where genetics and autoimmunity are the whole story, type 2 is strongly influenced by modifiable factors. That’s why public health efforts focus heavily on weight management, physical activity, and early screening for prediabetes as the primary tools for slowing the epidemic.