Type 2 diabetes is by far the most common form of diabetes. Of the 40.1 million people living with diabetes in the United States, roughly 90 to 95 percent have type 2. Type 1 diabetes accounts for about 2.1 million diagnosed cases, and the remaining fraction includes rarer forms like gestational diabetes and other genetic subtypes.
How Type 2 Differs From Type 1
The core difference comes down to what goes wrong with insulin. In type 1 diabetes, the immune system destroys the cells in the pancreas that produce insulin, so the body can’t make it at all. This usually appears in childhood or adolescence and requires insulin from the start.
Type 2 diabetes works differently. Your body still produces insulin, but your cells gradually stop responding to it properly. This is called insulin resistance. The pancreas tries to compensate by pumping out more insulin, but over time it can’t keep up. Blood sugar rises, first into a range called prediabetes, and eventually into full diabetes. Obesity is the most common driver of this process. Excess body fat reduces the number of functioning insulin receptors on cells and disrupts the signaling pathways that let glucose enter.
Why Type 2 Is So Widespread
Type 2 diabetes is closely tied to lifestyle and genetic factors that affect a huge portion of the population. You’re at higher risk if you are overweight or obese, are 35 or older, have a family history of diabetes, or are physically inactive. Certain racial and ethnic groups, including Black, Hispanic, Asian American, American Indian, and Pacific Islander populations, face elevated risk as well.
Body measurements matter in specific ways. Adults with a BMI of 25 or higher are considered overweight and at increased risk, though the threshold is lower for Asian Americans (BMI of 23 or higher). Men with a waist circumference over 40 inches and women with a waist over 35 inches also carry higher risk, regardless of overall weight. A history of gestational diabetes or giving birth to a baby weighing 9 pounds or more raises a woman’s lifetime risk.
The disease is no longer limited to middle-aged and older adults. Among young people in the U.S., the rate of new type 2 diabetes diagnoses doubled between 2002 and 2018, going from 9 to 18 per 100,000 per year. That’s a roughly 5 percent annual increase. The typical age of diagnosis in this younger group is around 16, and the sharpest increases have been among Asian/Pacific Islander, Hispanic, and Black youth.
Symptoms That Develop Slowly
One reason type 2 diabetes is so common yet so underdiagnosed is that symptoms creep in gradually. Globally, an estimated 43 percent of adults with diabetes don’t know they have it. In the U.S., more than 1 in 4 adults with diabetes are undiagnosed.
The symptoms themselves can be easy to dismiss or attribute to other things: increased thirst, urinating more often, feeling hungrier than usual, fatigue, blurred vision, and dry skin. Cuts and sores may heal noticeably slower. Some people develop tingling or numbness in their hands or feet, which signals early nerve involvement. Women may notice recurring yeast infections or urinary tract infections. Many people have no obvious symptoms at all until a blood test catches it.
How It’s Diagnosed
Three common blood tests can confirm a diabetes diagnosis. The A1C test measures your average blood sugar over the past two to three months. An A1C of 6.5 percent or higher on two separate tests means diabetes. Between 5.7 and 6.4 percent is prediabetes, and below 5.7 is normal.
A fasting blood sugar test checks your level after an overnight fast. Normal is below 100 mg/dL. Between 100 and 125 mg/dL falls into the prediabetes range, and 126 mg/dL or higher on two separate tests confirms diabetes. A glucose tolerance test follows a similar overnight fast, then measures how your body handles a sugary drink over two hours. Your doctor may use one or more of these depending on the situation.
Long-Term Complications
Sustained high blood sugar damages blood vessels and nerves throughout the body, which is why type 2 diabetes can affect so many different organs over time. The most serious complications include:
- Heart disease and stroke: People with diabetes are twice as likely to have heart disease or a stroke compared to those without it. This is the leading cause of death among people with type 2 diabetes.
- Kidney disease: About 1 in 3 adults with diabetes develops chronic kidney disease, which can progress to kidney failure if untreated.
- Nerve damage: Numbness and pain, most commonly in the feet and legs, though it can also affect digestion, blood vessels, and the heart.
- Eye damage: Diabetes can harm blood vessels in the retina, cloud the lens, or increase pressure inside the eye. All three can lead to vision loss.
- Amputations: When nerve damage and poor circulation combine, especially in the feet, infections can become severe enough to require amputation.
- Gum disease: Leads to tooth loss and can make blood sugar harder to control, creating a cycle that worsens both problems.
Depression is also more common among people with diabetes, and the risk increases as complications accumulate.
What Makes It Manageable
The same factors that drive type 2 diabetes also offer a path to managing it. Because insulin resistance is strongly linked to body weight and physical activity, losing even a moderate amount of weight (5 to 7 percent of body weight) can meaningfully improve blood sugar control. Regular physical activity helps your cells use insulin more effectively, independent of weight loss.
Most people with type 2 diabetes start with lifestyle changes and oral medications that help the body use insulin better or reduce the amount of sugar the liver releases. Some people eventually need insulin injections, especially as the disease progresses and the pancreas produces less on its own. The key difference from type 1 is that type 2 can sometimes be pushed into remission through sustained weight loss and lifestyle changes, particularly when caught early.
Prediabetes is the clearest warning sign and the best window for prevention. With 40.1 million Americans already living with diabetes and the diagnosis rate climbing in every age group, catching the disease in its early, reversible stage makes the biggest difference in long-term outcomes.