Type 2 diabetes is a chronic condition where your body can’t use insulin effectively to move sugar from your blood into your cells for energy. Over time, blood sugar levels stay elevated, which gradually damages blood vessels, nerves, and organs throughout the body. It accounts for roughly 90 to 95% of all diabetes cases and affects nearly 16% of U.S. adults, though about 4.5% of those people don’t know they have it.
How Type 2 Diabetes Develops
Your body breaks down most of the food you eat into glucose, a simple sugar that enters your bloodstream. Insulin, a hormone made by your pancreas, acts like a key that lets glucose into your cells. In type 2 diabetes, your cells stop responding normally to insulin. This is called insulin resistance. Your pancreas compensates by producing more insulin, but eventually it can’t keep up. The result is a slow, steady rise in blood sugar that can go undetected for years.
This is different from type 1 diabetes, where the immune system destroys the insulin-producing cells in the pancreas entirely. In type 2, the pancreas still makes insulin, but either not enough or the body doesn’t use it well. The distinction matters because the causes, typical age of onset, and treatment approaches differ significantly.
Who Is at Risk
Type 2 diabetes has both genetic and lifestyle roots. Having a parent or sibling with the condition raises your risk, and certain racial and ethnic groups face disproportionately higher rates, including Black, Hispanic/Latino, American Indian, Alaska Native, and some Asian American and Pacific Islander populations. Age plays a role too: risk climbs after 45.
Modifiable risk factors include carrying excess weight (especially around the abdomen), being physically active fewer than three times a week, and having a history of gestational diabetes or giving birth to a baby weighing over 9 pounds. Non-alcoholic fatty liver disease and prediabetes are also strong predictors. Prediabetes, where blood sugar is elevated but not yet in the diabetic range, is essentially an early warning signal that the condition is developing.
Symptoms That Develop Slowly
One of the trickiest things about type 2 diabetes is that symptoms can take years to appear, and many people have no noticeable symptoms at all. When they do show up, the most common signs include urinating more frequently, feeling unusually thirsty, persistent fatigue, and blurred vision. You might also notice that cuts or sores heal slowly, or that you’re getting more frequent infections like urinary tract infections, skin infections, or yeast infections. Some people feel hungrier than usual even after eating a full meal.
Because these symptoms tend to creep in gradually, they’re easy to dismiss or attribute to aging, stress, or other causes. That’s a big part of why so many cases go undiagnosed.
How It’s Diagnosed
Doctors use a few straightforward blood tests to diagnose type 2 diabetes. The most common is the A1C test, which measures your average blood sugar over the past two to three months. An A1C of 6.5% or higher indicates diabetes. A fasting blood sugar test (taken after at least 8 hours without eating) of 126 mg/dL or above also qualifies. A third option is an oral glucose tolerance test, where you drink a sugary solution and have your blood drawn two hours later; a reading of 200 mg/dL or more confirms the diagnosis.
The U.S. Preventive Services Task Force recommends routine screening for adults aged 35 to 70 who are overweight or obese, even if they have no symptoms. Screening should start earlier for people in higher-risk racial and ethnic groups, and at a lower body mass index (23 instead of 25) for Asian Americans, who can develop diabetes at lower weights.
What Happens if Blood Sugar Stays High
Uncontrolled type 2 diabetes damages the body through persistently elevated blood sugar. The cardiovascular system takes the biggest hit. Diabetes tends to lower “good” HDL cholesterol while raising triglycerides and “bad” LDL cholesterol, which increases the risk of heart disease and stroke. Cardiovascular disease is the leading cause of death among people with type 2 diabetes.
High blood sugar also damages small blood vessels and nerves throughout the body. In the eyes, this can lead to diabetic retinopathy, where damaged blood vessels in the retina impair vision. In the kidneys, it can cause chronic kidney disease. Nerve damage, most commonly in the feet and legs, causes numbness and pain and can also affect digestion and heart function. In severe cases, the combination of poor blood flow and nerve damage in the feet leads to infections that don’t heal, sometimes requiring amputation.
These complications aren’t inevitable. They develop over years of poorly managed blood sugar, and keeping levels in a healthy range dramatically reduces the risk of all of them.
Treatment and Management
Lifestyle changes form the foundation of treatment. Losing a modest amount of weight, eating a balanced diet that limits refined carbohydrates and added sugars, and getting regular physical activity all improve how your body uses insulin. For many people, these changes alone can bring blood sugar into a healthier range.
When lifestyle changes aren’t enough, medication comes next. Metformin has long been the standard first-line drug. It’s effective, inexpensive, widely available, and has been shown to reduce the risk of cardiovascular events and complications affecting small blood vessels. A newer class of medications called GLP-1 receptor agonists has become increasingly prominent in treatment guidelines. These drugs help lower blood sugar, promote weight loss, and reduce the risk of heart attacks and strokes. Current guidelines now prefer GLP-1 based therapies over insulin for most people who need additional blood sugar control beyond metformin, in part because they carry a lower risk of dangerously low blood sugar and help with weight management, though they can cause gastrointestinal side effects like nausea.
For people with established heart disease or kidney disease, medications that protect those organs are prioritized regardless of how well blood sugar is already controlled. Treatment is highly individualized. Your doctor will consider your A1C level, other health conditions, weight, and risk factors when choosing the right approach.
Can Type 2 Diabetes Be Reversed?
Remission is possible for some people. An international consensus defines remission as maintaining an A1C below 6.5% for at least three months without taking any diabetes medication. This can happen through significant weight loss, dietary changes, or bariatric surgery. It’s more likely in people who are diagnosed early and who haven’t had the condition for many years.
Remission doesn’t mean the disease is cured. The underlying tendency toward insulin resistance remains, and blood sugar can rise again over time. People who achieve remission still need regular monitoring.
Prevention Is Highly Effective
The landmark Diabetes Prevention Program trial demonstrated that intensive lifestyle changes, focused on modest weight loss (about 5 to 7% of body weight) and 150 minutes of physical activity per week, reduced the risk of developing type 2 diabetes by 58% in people with prediabetes. That’s nearly twice as effective as medication alone, which reduced risk by 31%. Over 21 years of follow-up, participants in the lifestyle group still had a 24% lower cumulative rate of diabetes compared to those who received no intervention.
These numbers are striking because the lifestyle changes required are achievable. For someone who weighs 200 pounds, a 5% loss is just 10 pounds. Combined with regular walking or other moderate activity, this level of change meaningfully alters the trajectory of the disease before it starts.