Diabetes mellitus is a chronic condition affecting millions of people worldwide, where blood sugar levels rise higher than they should. While there’s no cure yet, learning about the condition and managing it effectively can help you live a full, healthy life and prevent serious complications.

Understanding Diabetes and Its Reach

Diabetes is a condition that develops when your body struggles to properly manage blood sugar, also known as glucose. This happens either because your pancreas (an organ behind the stomach) doesn’t make enough insulin, or because your body’s cells don’t respond to insulin the way they should. Insulin acts like a key that unlocks your cells, allowing glucose from your bloodstream to enter and provide energy. Without enough insulin or proper insulin function, glucose builds up in your blood instead of powering your cells.^[1]

The scale of this health challenge is significant. In 2022, about 14% of adults aged 18 and older around the world were living with diabetes, which represents an increase from 7% in 1990. The number of people with diabetes rose from 200 million in 1990 to 830 million in 2022. More than half of adults living with diabetes were not taking medication for their condition in 2022.^[7]

In the United States alone, more than 38 million people have diabetes, which is about 1 in 10 Americans. Many don’t even realize they have it. The condition was the seventh leading cause of death in the country, and diabetes affects people of all ages, though certain types are more common at different life stages.^[1][4]

Diabetes has been rising more rapidly in low- and middle-income countries compared to high-income countries. Treatment coverage was lowest in these same regions, creating disparities in care and outcomes. In 2021, diabetes directly caused 1.6 million deaths worldwide, and nearly half of all deaths from diabetes occurred before the age of 70.^[7]

Different Forms of the Condition

Diabetes is not a single disease but rather a group of related conditions. The most common form is Type 2 diabetes, which accounts for the majority of cases. With Type 2 diabetes, your body doesn’t use insulin properly, a state called insulin resistance. Over time, the pancreas can’t keep up with the body’s increased need for insulin. Type 2 diabetes mainly affects adults, but children and teenagers are increasingly being diagnosed as well.^[1][2]

Type 1 diabetes is quite different. It’s an autoimmune disease, meaning your immune system mistakenly attacks and destroys the insulin-producing cells in your pancreas. People with Type 1 diabetes need to take insulin every day to survive. This type usually appears in children and young adults, though it can develop at any age. Up to 10% of people with diabetes have Type 1.^[1][2]

Gestational diabetes develops during pregnancy in women who have never had diabetes before. This type usually goes away after the baby is born, but it increases the mother’s risk of developing Type 2 diabetes later in life. Babies born to mothers with gestational diabetes are also at higher risk for obesity and Type 2 diabetes as they grow older.^[2]

Prediabetes is a warning stage that comes before Type 2 diabetes. Blood glucose levels are higher than normal but not high enough to be diagnosed as diabetes. In the United States, about 1 in 3 adults has prediabetes, and more than 8 in 10 people with prediabetes don’t know they have it. This stage offers a critical opportunity to make changes and prevent the progression to Type 2 diabetes.^[2][3]

There are also less common forms. Type 3c diabetes happens when the pancreas is damaged by conditions like pancreatitis, pancreatic cancer, or cystic fibrosis. LADA (latent autoimmune diabetes in adults) develops slowly, like an autoimmune reaction similar to Type 1 but in adults over 30. MODY (maturity-onset diabetes of the young) results from inherited genetic mutations and commonly runs in families. Neonatal diabetes is a rare form occurring within the first six months of life.^[1]

What Causes This Condition

The causes of diabetes vary significantly depending on the type. Type 1 diabetes is thought to be caused by an autoimmune reaction where the body mistakenly attacks itself. This reaction destroys the insulin-producing beta cells in the pancreas. Currently, no one knows exactly what triggers this autoimmune response, and there is no known way to prevent Type 1 diabetes.^[2][4]

Type 2 diabetes develops when the body becomes resistant to insulin or when the pancreas can’t produce enough insulin to overcome that resistance. This type develops over many years. The exact cause isn’t fully understood, but it involves a combination of genetic factors and lifestyle choices. Unlike Type 1, Type 2 diabetes is often preventable through healthy lifestyle changes.^[2]

Gestational diabetes occurs because hormonal changes during pregnancy can make cells more resistant to insulin. The pancreas tries to compensate by making extra insulin, but sometimes it can’t keep up. This leads to high blood sugar during pregnancy. After delivery, hormone levels typically return to normal and the diabetes usually resolves.^[8]

Who Is Most at Risk

Several factors increase your chances of developing Type 2 diabetes. Being overweight or having obesity significantly raises risk because excess body fat, especially around the abdomen, makes cells more resistant to insulin. Physical inactivity also contributes, as regular exercise helps your body use insulin more effectively.^[8]

Family history plays an important role. If a parent or sibling has Type 2 diabetes, your risk increases. Certain racial and ethnic groups face higher risk, including African Americans, Hispanic or Latino Americans, American Indians, and some Pacific Islanders and Asian Americans. The reasons for these differences aren’t fully understood but likely involve both genetic and environmental factors.^[8]

Age is another factor. The risk of Type 2 diabetes increases as you get older, especially after age 35, because the body’s ability to manage sugar declines with age. However, Type 2 diabetes is increasingly being diagnosed in younger people, including children and teenagers, largely due to rising obesity rates.^[3]

Women who had gestational diabetes during pregnancy have a much higher risk of developing Type 2 diabetes later. Women with polycystic ovary syndrome (PCOS) also face increased risk. Having prediabetes is one of the strongest risk factors, as it often progresses to Type 2 diabetes if lifestyle changes aren’t made.^[2]

Recognizing the Warning Signs

Diabetes symptoms depend on how high your blood sugar is. Some people, especially those with prediabetes or Type 2 diabetes in its early stages, may not have any symptoms at all. In Type 1 diabetes, symptoms tend to come on quickly and be more severe, while Type 2 diabetes symptoms may develop gradually over many years and can be mild enough to go unnoticed.^[6]

Common symptoms that affect both Type 1 and Type 2 diabetes include feeling much thirstier than usual and needing to urinate more often, including during the night. Many people experience unexplained weight loss even when they’re eating normally. You might feel very tired and weak, or notice that you’re more irritable or experiencing other mood changes.^[6]

Blurry vision is another frequent symptom, as high blood sugar can affect the lens of the eye. Sores or cuts that heal very slowly are also common, as elevated blood glucose affects the body’s ability to repair itself. People with diabetes may get more infections than usual, particularly infections of the gums, skin, or vaginal area.^[6]

Some people with Type 1 diabetes may have ketones in their urine. Ketones are byproducts that form when the body breaks down muscle and fat for energy because it can’t use glucose properly. This can be dangerous and requires immediate medical attention. Other symptoms can include tingling, numbness, or pain in the hands or feet.^[6]

Because Type 2 diabetes symptoms can be so mild, many people don’t realize they have it until they develop complications or the condition is discovered during routine blood tests. This is why regular screening is so important, especially if you have risk factors.^[7]

Preventing Diabetes Before It Starts

While Type 1 diabetes cannot currently be prevented, Type 2 diabetes is often preventable through healthy lifestyle changes. These same changes can also help people with prediabetes avoid progressing to full diabetes. A healthy diet is one of the most powerful prevention tools available. This means eating a variety of fruits, vegetables, and whole grain foods like whole wheat bread, brown rice, and oats, along with pulses such as chickpeas and lentils.^[7][17]

Limiting processed foods that are high in salt, sugar, and unhealthy fats is important. This includes reducing intake of items like bacon, chips, cheese, sweets, and biscuits. Avoiding sugary drinks like soft drinks and choosing water or unsweetened tea instead can make a significant difference. Eating smaller portions throughout the day, rather than three large meals, can help keep blood sugar levels steadier.^[17]

Regular physical activity is equally crucial. The recommendation is to spend at least 2.5 hours per week doing activities that leave you slightly out of breath, such as walking, biking, or swimming. Physical activity helps your body use insulin more effectively and helps maintain a healthy weight. Even small increases in activity can make a meaningful difference.^[7][17]

Losing weight if you’re overweight can significantly reduce your risk. Even losing 5 to 10 pounds can help. Weight loss happens most effectively through a combination of healthy eating and regular exercise. Maintaining a normal body weight and avoiding tobacco use are also important preventive measures. Smoking increases the harmful effects of diabetes, so quitting is especially important for those at risk or already diagnosed.^[7][22]

Getting enough sleep is another often-overlooked factor in diabetes prevention. Poor sleep can affect how your body processes sugar and can increase stress hormones that raise blood sugar. Keeping your bedroom dark and cool, avoiding screens before bed, and maintaining a regular sleep schedule can all help.^[18]

How Diabetes Changes Your Body

Understanding what happens inside your body helps explain why diabetes causes the symptoms and complications it does. Normally, when you eat, your digestive system breaks down carbohydrates into simple sugars, mainly glucose. This glucose enters your bloodstream, which carries it throughout your body. When blood glucose levels rise, your pancreas releases insulin, which signals cells throughout your body to take in the glucose and use it for energy.^[1][3]

In people without diabetes, blood glucose levels normally vary within a narrow range, about 70 to 110 milligrams per deciliter of blood. The pancreas adjusts insulin production throughout the day to keep glucose levels stable. After you eat a meal, glucose levels rise, insulin production increases, and within about two hours, glucose returns to pre-meal levels.^[3]

In Type 1 diabetes, the immune system destroys the beta cells in the pancreas that make insulin. Without these cells, little or no insulin is produced. Glucose can’t enter cells properly, so it accumulates in the bloodstream while cells are starved of energy. The body may start breaking down fat and muscle for fuel, producing ketones as a byproduct, which can be dangerous.^[4][9]

In Type 2 diabetes, cells become resistant to insulin’s signals. At first, the pancreas compensates by making extra insulin to try to overcome this resistance. For a while, this works and blood glucose stays relatively normal. But over time, the pancreas becomes exhausted from overproduction and can’t keep up. Blood glucose levels then rise and stay elevated. Eventually, the pancreas may produce less and less insulin.^[9]

High blood glucose levels over time damage blood vessels throughout the body. Small blood vessels in the eyes, kidneys, and nerves are particularly vulnerable. Larger blood vessels that supply the heart, brain, and legs can also be affected. This damage happens gradually and is why controlling blood sugar is so important for preventing complications.^[1][3]

Over time, consistently high blood glucose causes serious health problems. It can damage nerves, a condition called diabetic neuropathy, which often causes pain, tingling, or numbness in the hands and feet. It can harm the kidneys, potentially leading to chronic kidney disease or kidney failure. High blood sugar damages the small blood vessels in the eyes, causing vision problems and potentially blindness. It increases the risk of heart attack, stroke, and poor circulation in the legs, which can lead to serious infections and, in severe cases, amputation.^[1][7]