Type 1 diabetes affects an estimated 9.5 million people worldwide as of 2025, and it is far less limited in who it strikes than most people assume. While long considered a childhood disease, emerging data shows that more than half of all type 1 diabetes cases develop in people over 20. It occurs across every race, ethnicity, and geographic region, though some groups face significantly higher risk than others.
Age at Diagnosis: Not Just a Childhood Disease
The stereotype of type 1 diabetes as something only children get is outdated. In a study of more than 1.3 million U.S. adults, the median age at diagnosis was 24 years old. While diagnoses peak around age 15, 37% of patients reported being diagnosed after age 30. Researchers at Johns Hopkins estimate that up to 62% of all type 1 diabetes cases develop in adulthood.
This matters because adults diagnosed later in life are often initially misdiagnosed with type 2 diabetes. A related condition called latent autoimmune diabetes in adults (LADA) accounts for roughly 9% of all people diagnosed with diabetes. LADA is essentially a slower-progressing form of autoimmune diabetes that looks like type 2 at first but eventually requires insulin, just like type 1. Men and racial or ethnic minorities tend to be diagnosed even later than women and non-Hispanic White adults, which can delay proper treatment.
Sex Differences
Men are more likely to develop type 1 diabetes than women. CDC data shows a prevalence of 0.64% in men compared to 0.46% in women, a statistically significant gap. The reasons aren’t fully understood, but the pattern holds across multiple populations and age groups.
Race and Ethnicity in the U.S.
Type 1 diabetes affects every racial and ethnic group, but rates are not evenly distributed. Among U.S. adults, non-Hispanic White individuals have the highest prevalence at 5.9 per 1,000 people. Non-Hispanic Black adults follow at 4.8 per 1,000, and Hispanic adults at 4.0 per 1,000.
Among children and teens, the gap narrows. Hispanic youth had a prevalence of 3.5 per 1,000, while non-Hispanic White youth were at 3.9 per 1,000. These numbers suggest that while White populations currently carry the highest burden in the U.S., type 1 diabetes is not rare in any group, and rates among non-White populations may be rising.
Geography: A 30-Fold Difference Across Countries
Where you live dramatically shapes your risk. There is a more than 30-fold variation in annual incidence rates around the world, ranging from less than 1 per 100,000 people in China to more than 30 per 100,000 in parts of Northern Europe and Eastern Africa. Finland has the world’s highest childhood incidence rate at 52.2 per 100,000, followed by Sweden at 44.1 and Kuwait at 41.7. Populations of Northern European descent consistently show the highest rates, but the Middle East and North Africa are seeing rapid increases.
Globally, about 513,000 new cases were diagnosed in 2025 alone. Of those, 164,000 were in children under 15 and 58,000 were in teens aged 15 to 19. The remaining roughly 290,000 new diagnoses were in adults, reinforcing that this is not predominantly a pediatric condition by the numbers.
Genetics and Family History
Your genes play the largest role in determining whether your immune system might attack the insulin-producing cells in your pancreas. The strongest genetic link involves a set of immune system genes that help your body distinguish its own cells from invaders. Specific variations in these genes can make the immune system more likely to misidentify pancreatic cells as threats.
Family history increases risk in a pattern that surprises many people. Having a father with type 1 diabetes raises a child’s risk two to three times more than having a mother with the condition. In one large study of nearly 5,000 newly diagnosed children, 5.1% had a father with type 1 diabetes, while only 2.8% had an affected mother. About 1.9% had a sibling with the disease. Still, the vast majority of people who develop type 1 diabetes, roughly 90%, have no close family member with it.
Environmental Triggers
Genetics loads the gun, but something in the environment pulls the trigger. In people who carry susceptibility genes, certain viral infections appear to set off the autoimmune attack on the pancreas. Enteroviruses, particularly one called Coxsackie B, are the leading suspects. These common viruses have been found directly in the pancreatic tissue of people with type 1 diabetes, and studies across European, African, Asian, Australian, and Latin American populations have linked enterovirus infection to increased disease risk.
Rotavirus, mumps, rubella, and cytomegalovirus have also been associated with higher risk, though the evidence is strongest for enteroviruses. The process is not instant. A viral infection may kick off a slow autoimmune process that destroys insulin-producing cells over months or even years before symptoms appear. This helps explain why type 1 diabetes can seem to come out of nowhere in someone with no family history.
A Growing Global Problem
Type 1 diabetes is becoming more common. The global count rose from 8.4 million people in 2021 to 9.5 million in 2025, a 13% increase in just four years. Annual incidence is climbing by about 2.4% per year. This acceleration is too fast to be explained by genetics alone, which points to changing environmental factors, though researchers have not pinpointed exactly which ones are driving the increase. The rise is happening in both high-income and low-income countries, across age groups, and in populations that previously had low rates.