Type 1 diabetes accounts for about 5.8% of all diagnosed diabetes cases, making it far less common than type 2, which represents roughly 91%. Despite being a small slice of the overall diabetes population, it affects millions of people worldwide, and its numbers have been climbing steadily for decades.
How Many People Have Type 1 Diabetes
Globally, 1.8 million children and adolescents under 20 are living with type 1 diabetes, according to the International Diabetes Federation. That figure only captures young people. When adults diagnosed in childhood and those diagnosed later in life are included, the total is significantly higher. In the United States alone, roughly 1.6 million people of all ages are estimated to have type 1 diabetes.
To put that in perspective, if you gathered 100 people with any form of diabetes in a room, about 6 of them would have type 1, around 91 would have type 2, and the remaining 3 would have rarer forms like gestational diabetes or monogenic diabetes. Type 1 is uncommon relative to type 2, but it is not rare. It is one of the most common chronic autoimmune conditions in children.
Incidence Is Rising, Especially in Children
Type 1 diabetes has become significantly more common over the past few decades. A long-running study in southwest Germany tracked new diagnoses in children over 38 years and found that the incidence rate doubled between 1987 and 2008, rising from about 10 new cases per 100,000 children per year to 23 per 100,000. That works out to a 4% annual increase sustained over two decades. Since 2008, the rate in that population has plateaued at the higher level rather than continuing to climb.
Similar upward trends have been documented across Europe, North America, and parts of Asia. The reasons are not fully understood. Genetics alone cannot explain a doubling in one generation, so researchers point to environmental factors: changes in early childhood infections, shifts in gut bacteria, dietary patterns in infancy, and possibly viral triggers. The COVID-19 pandemic also appeared to temporarily accelerate new diagnoses in some populations, though it is still unclear whether those cases were truly caused by the virus or simply unmasked earlier.
Who Gets Type 1 Diabetes
Type 1 diabetes can develop at any age, but it most commonly appears in two peak windows: between ages 4 and 7, and again between 10 and 14. Many people assume it only affects children (the old name “juvenile diabetes” reinforced this), but roughly half of all new type 1 diagnoses actually occur in adults over 18.
Family history plays a role, though a smaller one than most people expect. Having a parent or sibling with type 1 diabetes does increase your risk, but the vast majority of people who develop it have no close relative with the condition. The overall lifetime risk in the general population is low, somewhere around 0.4%, while a sibling of someone with type 1 faces a risk closer to 3-5%. That is meaningfully higher in relative terms but still means most siblings will never develop it.
In the U.S., type 1 diabetes is most common among white, non-Hispanic populations, though it occurs across all racial and ethnic groups. This pattern differs from type 2 diabetes, where rates are highest among American Indian, Black, and Hispanic adults.
Why Adults Are Often Misdiagnosed
When type 1 diabetes develops in adults, it frequently gets misclassified as type 2 at first. This happens because doctors naturally consider the most likely explanation: type 2 diabetes is vastly more common in adults, and the early symptoms (increased thirst, frequent urination, fatigue) look identical. An adult who walks into a clinic with high blood sugar is almost always started on type 2 treatments.
The misdiagnosis matters because the two conditions require fundamentally different management. Type 1 is an autoimmune disease in which the immune system destroys the cells that produce insulin. Without insulin from day one, blood sugar becomes dangerously uncontrolled. Type 2, by contrast, typically involves insulin resistance, and many patients can initially manage it with lifestyle changes or oral medications. An adult with type 1 who is treated as though they have type 2 will often deteriorate over weeks or months as their remaining insulin production dwindles, sometimes ending up in the emergency room with a serious complication called diabetic ketoacidosis before the correct diagnosis is made.
Simple blood tests for autoantibodies can distinguish type 1 from type 2, but they are not always ordered at the first visit. If you are diagnosed with type 2 diabetes but your blood sugar is difficult to control despite following your treatment plan, or if you are losing weight unexpectedly, asking about autoantibody testing is reasonable.
How Type 1 Compares Globally
Type 1 diabetes is not evenly distributed around the world. The highest rates are found in Finland and Sardinia, where the incidence in children exceeds 60 per 100,000 per year, more than double the rate in most other European countries. Nordic countries in general tend to have higher rates. East Asian and sub-Saharan African countries report some of the lowest incidence figures, though underdiagnosis and limited data collection in lower-income regions make true comparisons difficult. A child in a remote area without access to insulin can die before ever receiving a formal diagnosis, meaning official statistics in some countries undercount the real burden.
The geographic variation strongly suggests that environmental and genetic factors interact in complex ways. Populations with higher frequencies of certain immune system gene variants tend to have higher rates, but migration studies show that people who move from low-incidence to high-incidence countries see their risk increase over a generation, reinforcing the idea that something in the environment is pulling the trigger.