Type 2 diabetes is a chronic condition where your body stops responding properly to insulin, the hormone that moves sugar from your blood into your cells for energy. It accounts for roughly 90% to 95% of all diabetes cases, and the number of adults living with diabetes worldwide has now surpassed 800 million, more than quadrupling since 1990. Global prevalence in adults rose from 7% to 14% between 1990 and 2022.
How Type 2 Diabetes Develops
Insulin acts like a key that unlocks your cells so they can absorb glucose from the bloodstream. In type 2 diabetes, cells in your muscles, liver, and fat tissue gradually stop responding to that key, a process called insulin resistance. Your pancreas compensates by pumping out more and more insulin to keep blood sugar levels normal. For a while this works, but it puts the insulin-producing cells (called beta cells) under increasing strain.
Over months or years, those beta cells begin to wear out. Insulin production drops, blood sugar rises, and diabetes sets in. The buildup of fat in the liver and skeletal muscle is considered one of the main drivers of insulin resistance, though the full picture is still being mapped out. This slow progression is why many people spend years in a “prediabetes” phase before crossing into a full diagnosis.
Symptoms and Warning Signs
Type 2 diabetes symptoms often take several years to develop, and some people don’t notice any symptoms at all. When they do appear, the most common include:
- Frequent urination
- Increased thirst and hunger
- Unexplained weight loss
- Fatigue
- Blurry vision
- Irritability or mood changes
- Frequent urinary tract infections or yeast infections
A few symptoms are more characteristic of type 2 specifically: cuts and sores that heal very slowly, dark patches of skin around the neck, armpits, or groin (a condition called acanthosis nigricans), and numbness or tingling in the hands or feet. That last one signals early nerve involvement and is worth paying attention to.
Who Is Most at Risk
Weight is the single biggest modifiable risk factor. Most adults with a BMI of 25 or higher are considered overweight and face elevated risk. The thresholds differ by ethnicity: Asian Americans are considered overweight at a BMI of 23, while Pacific Islanders at 26. Waist circumference matters independently of BMI. Men with a waist measurement over 40 inches and women over 35 inches carry higher risk, because abdominal fat is closely linked to insulin resistance.
Family history plays a significant role. If a parent or sibling has type 2 diabetes, your own risk goes up substantially. Certain ethnic groups, including African American, American Indian, Asian American, Hispanic/Latino, and Pacific Islander populations, face higher rates regardless of weight. Risk also rises after age 35, though children and teens can develop it too.
Other factors that increase your chances: a sedentary lifestyle or a job that involves sitting for long periods, a previous diagnosis of prediabetes, and a history of gestational diabetes or giving birth to a baby weighing 9 pounds or more.
How It Is Diagnosed
Diagnosis relies on blood tests that measure how much sugar is circulating in your blood. The two most common are the A1C test and fasting blood glucose.
The A1C test reflects your average blood sugar over the past two to three months. A result of 6.5% or higher means diabetes. A reading between 5.7% and 6.4% falls in the prediabetes range. Fasting blood glucose, taken after at least eight hours without eating, follows a similar pattern: 126 mg/dL or above indicates diabetes, while 100 to 125 mg/dL signals prediabetes. Because type 2 diabetes develops gradually, many people are first caught in that prediabetes window, which is actually the best time to intervene.
What Happens if Blood Sugar Stays High
Chronically elevated blood sugar damages blood vessels throughout the body, and the consequences show up in two broad categories. Small-vessel damage (microvascular complications) affects the eyes, kidneys, and nerves. Large-vessel damage (macrovascular complications) affects the heart, brain, and legs.
In the eyes, high blood sugar thickens the tiny capillaries of the retina, triggers abnormal new blood vessel growth, and can eventually cause vision loss. This is called diabetic retinopathy, and it’s the leading cause of new blindness in working-age adults. In the kidneys, damage to the filtering units progressively reduces kidney function and can lead to chronic kidney disease or kidney failure over time. Nerve damage, or neuropathy, most commonly starts in the feet and legs with tingling, numbness, or pain, and can also affect digestion, bladder function, and sexual health.
On the large-vessel side, type 2 diabetes significantly raises the risk of heart attack, stroke, and peripheral artery disease, where narrowed blood vessels reduce blood flow to the legs. Cardiovascular disease is the leading cause of death among people with type 2 diabetes. This is why modern treatment strategies focus not just on lowering blood sugar but on protecting the heart and kidneys.
Treatment and Medication
Metformin has been the first-line medication for type 2 diabetes for decades, mainly because it works, it’s safe, and it’s affordable. It helps lower blood sugar primarily by reducing the amount of glucose your liver releases into the bloodstream.
Two newer classes of medication have changed the treatment landscape significantly. One type works by helping your kidneys flush excess glucose out through urine, lowering blood sugar while also reducing the workload on the heart and kidneys. The other mimics a gut hormone that triggers insulin release after meals, slows digestion, and reduces appetite, which often leads to meaningful weight loss. Both classes have consistently shown reductions in heart attacks, strokes, and kidney disease progression in people who already have cardiovascular risk, making them important tools beyond just blood sugar control.
Your treatment plan depends on your A1C level, your weight, and whether you have existing heart or kidney disease. Some people manage well on one medication alone. Others eventually need a combination of two or three, and some may need insulin if their beta cells can no longer produce enough on their own.
Lifestyle Changes That Matter Most
Physical activity directly improves insulin sensitivity, meaning your cells become better at absorbing glucose even without additional medication. The target is at least 150 minutes of moderate-intensity activity per week, which works out to about 30 minutes on most days. Walking, cycling, and swimming all count. Spacing activity so you’re never inactive for more than two consecutive days helps maintain the effect.
Resistance training (lifting weights, using resistance bands, or bodyweight exercises) adds further benefit by building muscle tissue, which is one of the body’s biggest consumers of glucose. Combining aerobic exercise with resistance training two to three times a week tends to produce the best results for blood sugar control.
On the dietary side, patterns that emphasize vegetables, whole grains, lean proteins, and healthy fats while limiting refined carbohydrates and added sugars consistently improve glucose levels. Reducing carbohydrate intake has a direct effect because carbohydrates are the macronutrient that raises blood sugar the most. You don’t need to follow one specific named diet. The core principle is straightforward: eat fewer processed foods, more fiber, and control portion sizes.
Can Type 2 Diabetes Be Reversed?
Remission is the formal term, and it’s defined as maintaining an A1C below 6.5% for at least three months without taking any diabetes medication. This is achievable for some people, particularly those diagnosed within the past few years who are able to lose a significant amount of weight.
Weight loss is the most reliable path to remission. Losing 10% to 15% of body weight through dietary changes, increased activity, or bariatric surgery can reduce fat stored in the liver and pancreas, which restores insulin sensitivity and beta cell function. Remission doesn’t mean a permanent cure. The underlying tendency toward insulin resistance remains, and blood sugar levels need ongoing monitoring. Many people who achieve remission maintain it for years, but a return to previous habits typically brings blood sugar back up.
Even when full remission isn’t reached, meaningful weight loss and lifestyle changes consistently improve blood sugar, blood pressure, and cholesterol, all of which reduce the risk of the complications described above. In 2022, nearly 450 million adults with diabetes worldwide were going untreated, a 3.5-fold increase since 1990. Early action, even modest changes, makes a measurable difference in long-term outcomes.