Type 2 diabetes is by far the most common form, accounting for more than 95% of all diabetes cases worldwide. Of the 830 million people living with diabetes globally in 2022, the vast majority have type 2. In the United States alone, 40.1 million people have diabetes, and roughly 2.1 million of them have type 1, putting type 2 at well over 90% of the domestic total.
Why Type 2 Is So Much More Common
Type 1 and type 2 diabetes both involve problems with insulin, but they develop for very different reasons. Type 1 is an autoimmune condition where the body’s immune system destroys the cells in the pancreas that produce insulin. It typically appears in childhood or adolescence, and nothing about a person’s lifestyle triggers it. Type 2, on the other hand, develops when the body’s cells gradually stop responding to insulin the way they should, a process called insulin resistance.
Insulin resistance doesn’t happen overnight. In the years before type 2 diabetes appears, the pancreas compensates by pumping out more and more insulin to keep blood sugar levels normal. Eventually the pancreas can’t keep up, blood sugar rises, and diabetes develops. Because this process is driven largely by factors that affect huge portions of the population (excess weight, physical inactivity, aging), type 2 diabetes is far more widespread than type 1, which requires a specific genetic and immune trigger that is relatively rare.
Obesity is the single biggest driver. Studies have found that people with obesity are up to 80 times more likely to develop type 2 diabetes than those at a healthy weight. When excess fat accumulates in the liver and muscles, certain fat byproducts interfere with insulin’s ability to signal cells to absorb sugar from the blood. The more fat stored in these tissues, the worse insulin resistance becomes.
Who Is Most at Risk for Type 2
The CDC identifies several factors that raise your risk for type 2 diabetes and its precursor, prediabetes:
- Weight: Having overweight or obesity
- Age: Being 45 or older
- Family history: Having a parent or sibling with type 2
- Activity level: Being physically active fewer than three times a week
- Liver health: Having non-alcoholic fatty liver disease
- Pregnancy history: Having had gestational diabetes or delivering a baby weighing over 9 pounds
- Ethnicity: Being African American, Hispanic or Latino, American Indian, Alaska Native, Pacific Islander, or Asian American
Many of these risk factors overlap and compound one another. A person over 45 with a family history who is also sedentary and carrying extra weight faces considerably higher odds than someone with just one of these factors.
The Prediabetes Pipeline
One reason type 2 diabetes numbers keep climbing is the enormous pool of people with prediabetes. An estimated 115.2 million American adults, more than 2 in 5, currently have prediabetes. Their blood sugar is elevated above normal but not yet high enough to qualify as diabetes. The alarming part: 8 in 10 of them don’t know it.
Prediabetes is the stage where intervention is most effective. Modest weight loss (5% to 7% of body weight) and regular physical activity can significantly delay or prevent the progression to full type 2 diabetes. Without changes, though, many people with prediabetes will cross that threshold within a few years.
How Type 2 Is Diagnosed
Diagnosis typically comes from a blood test. A fasting blood sugar reading, an A1c test (which reflects your average blood sugar over the past two to three months), or an oral glucose tolerance test can all confirm diabetes. On the oral glucose tolerance test, a reading above 200 mg/dL two hours after drinking a sugary solution indicates diabetes, while a reading between 140 and 199 mg/dL falls in the prediabetes range. More than 1 in 4 adults with diabetes in the U.S. don’t know they have it, which is why routine screening matters, especially if you have risk factors.
Other Forms of Diabetes
Type 1 diabetes affects about 2.1 million people in the United States, including roughly 314,000 children and adolescents. Unlike type 2, it requires insulin from the day of diagnosis because the body produces little to none on its own. It cannot be prevented through lifestyle changes.
Gestational diabetes develops during pregnancy and affects an estimated 2% to 10% of pregnancies in the U.S. It usually resolves after delivery, but women who experience it have a significantly higher risk of developing type 2 diabetes later in life. Rarer forms, sometimes grouped under the label “other specific types,” include diabetes caused by genetic mutations, pancreatic disease, or certain medications, but collectively these account for a very small share of all cases.
A Global Problem That Keeps Growing
The worldwide scale of type 2 diabetes has changed dramatically in a single generation. In 1990, about 200 million people had diabetes. By 2022, that number had reached 830 million. The percentage of adults living with the disease doubled from 7% to 14% over the same period. Rising obesity rates, aging populations, and increasingly sedentary lifestyles in both high-income and low-income countries are fueling the trend, with no signs of slowing.