Diabetes

Diabetes mellitus, commonly known as diabetes, is a group of diseases where the body has trouble managing sugar in the blood. This happens because the pancreas does not make enough of a hormone called insulin, or because the body’s cells do not respond well to the insulin it makes. When this happens, sugar builds up in the blood and can cause many health problems.

People with diabetes often feel very thirsty, need to use the bathroom a lot, and may feel extra hungry. They might also lose weight without trying and have blurry vision. If diabetes is not treated, it can hurt the heart, eyes, kidneys, and nerves.

There are several types of diabetes. The most common is type 2, which usually develops in adults but can occur at any age. Type 1 diabetes is less common and often starts in childhood or young adulthood. It happens when the body’s immune system attacks the parts of the pancreas that make insulin. Another type, called gestational diabetes, can happen during pregnancy but usually goes away after the baby is born. Treatments for diabetes include insulin injections, medicines, and changes to diet and exercise.

The number of people with diabetes has grown quickly over the past few decades. In 1990, about 200 million people had diabetes, but by 2024, that number had risen to 828 million. Diabetes is now one of the leading causes of death worldwide, especially in poorer countries. Both men and women are equally affected, and the cost of caring for people with diabetes is very high, estimated at US$760 billion each year.

Signs and symptoms

Common signs of diabetes include feeling very thirsty, needing to use the bathroom a lot, feeling very hungry, and losing weight without trying. You might also feel tired, notice your vision is blurry, or have a strange smell in your urine. Some people with diabetes don’t show any signs at all.

Diabetes can sometimes cause serious health problems. One emergency is when the body makes too much of a special kind of energy, leading to feeling sick, having stomach pain, and breathing in a special way. Another emergency happens when blood sugar gets very high, causing dehydration and confusion. Low blood sugar from treatment can also cause sweating, shaking, and confusion. Over time, diabetes can affect blood vessels, leading to problems with the heart, eyes, kidneys, and nerves. It can also cause vision loss, kidney disease, nerve damage, and problems with hearing. People with diabetes should see a special eye doctor regularly to check their eyes.

Types

Diabetes is classified by the World Health Organization into six categories:

• Type 1 diabetes
• Type 2 diabetes
• Hybrid forms of diabetes
  (including slowly evolving, immune-mediated diabetes of adults and ketosis-prone type 2 diabetes)
• Hyperglycemia first detected during pregnancy
• Other specific types
• Unclassified diabetes

Diabetes is more variable than once thought, and individuals may have a combination of forms.

Type 1

Main article: Type 1 diabetes

Type 1 diabetes is the most common type in children and teens, but it can occur at any age. It happens when the body can no longer make insulin due to the loss of certain cells in the pancreas. This leads to very high blood sugar levels and often comes on suddenly.

Type 1 diabetes is partly inherited, and certain genes can increase the risk. Environmental factors, like a viral infection, may also trigger the disease in people who are genetically susceptible. It is not fully genetic, as identical twins do not always both develop the condition.

Type 2

Main article: Type 2 diabetes

Type 2 diabetes is the most common type and usually develops in adults, though it can occur in younger people as well. It happens when the body does not use insulin properly, and may also involve reduced insulin production. This type is often linked to lifestyle factors such as obesity, lack of physical activity, poor diet, and stress.

Certain diets, like those high in sugar-sweetened drinks and unhealthy fats, can increase the risk. Some medications and childhood experiences, such as neglect or abuse, can also raise the chances of developing type 2 diabetes later in life.

Gestational diabetes

Main article: Gestational diabetes

Gestational diabetes occurs in pregnancy when the body cannot make enough insulin to meet the increased needs of the developing baby. It usually appears in the second or third trimester and often goes away after the baby is born, but some women may develop type 2 diabetes later.

Maturity-onset diabetes of the young

Main article: Maturity-onset diabetes of the young

Maturity-onset diabetes of the young (MODY) is a rare form of diabetes that runs in families. It is caused by gene mutations that affect insulin production and can appear at different ages. People with MODY may manage it without insulin.

Type 5 (malnutrition-related)

Malnutrition-related diabetes involves low insulin production due to poor nutrition rather than autoimmune damage. It does not cause the same symptoms as type 1 diabetes.

Other types

Other types of diabetes can result from various causes, such as genetic defects, diseases affecting the pancreas, hormonal imbalances, infections, or certain medications. One example is when a person with type 1 diabetes also develops insulin resistance, sometimes called "double diabetes."

Unofficial types include conditions like insulin resistance linked to Alzheimer's disease, though these terms are not commonly used in medical practice.

Pathophysiology

Insulin is a special hormone that helps your body take sugar, called glucose, from the blood into your cells where it can be used for energy. Without enough insulin or when cells don’t respond well to it, sugar stays in the blood instead of going into cells.

Your body gets sugar mainly from food, from breaking down stored sugar in your liver, and from making sugar from other materials. Insulin helps keep sugar levels balanced. It tells your body to store sugar, use it for energy, or turn it into other important things.

When there isn’t enough insulin or cells don’t listen to it, sugar can’t get into cells properly. This means too much sugar stays in the blood, which can make you very thirsty, need to go to the bathroom a lot, and feel extra hungry.

Diagnosis

See also: Glycated hemoglobin and Glucose tolerance test

Doctors can find out if someone has diabetes by checking the amount of sugar in their blood. There are a few ways they can do this:

• A fasting plasma glucose level of 7.0 mmol/L (126 mg/dL) or higher, measured in the morning after not eating overnight.
• A plasma glucose level of 11.1 mmol/L (200 mg/dL) or higher two hours after drinking a special sugar solution, as part of a glucose tolerance test.
• Signs of high blood sugar along with a plasma glucose level of 11.1 mmol/L (200 mg/dL) or higher, whether fasting or not.
• Glycated hemoglobin (HbA_1C) of 48 mmol/mol (6.5 DCCT%) or higher.

If a test shows possible diabetes, doctors will usually repeat the test another day to be sure. Checking fasting glucose is often easier and quicker than other tests.

Prevention

See also: Prevention of type 2 diabetes

There is no known preventive measure for type 1 diabetes. However, type 2 diabetes—which makes up most cases—can often be prevented or delayed by keeping a normal body weight, being active, and eating a healthy diet. Doing more than 90 minutes of activity each day can lower the risk by 28%. Eating foods like whole grains and fiber, and choosing good fats from nuts, vegetable oils, and fish helps. Avoiding sugary drinks and eating less red meat can also help. Quitting smoking is another important step to prevent diabetes.

The main things that raise the risk for type 2 diabetes, like extra weight, poor diet, not being active, and smoking, are the same around the world. These risks are linked to big changes in society, such as globalization, cities growing, people getting older, and how health policy is made.

Comorbidity

People with diabetes often face other health problems that can make their care more expensive and complicated. These can include infections in the lungs, urinary tract, and skin, as well as heart problems, high blood pressure, and kidney disease. Because of these extra health issues, people with diabetes may need more medical help.

Those with type 1 diabetes are also more likely to have other conditions where the body’s immune system attacks itself. For example, about one in four people with type 1 diabetes also have another such condition, and some may have celiac disease, which affects how the body processes certain foods. Keeping blood sugar levels under control is very important for helping to prevent or delay these additional health problems.

Management

Managing diabetes means keeping blood sugar levels close to normal without causing them to drop too low. This can be done through changes in diet, exercise, weight loss, and using the right medicines such as insulin or oral medications.

Learning about diabetes and taking an active role in treatment is important. People who keep their blood sugar levels well-managed often have fewer and less serious problems. The goal is to have a certain blood sugar measure (called HbA_1C) below a specific number. It’s also important to watch for other health issues that can make diabetes worse. These include smoking, high blood pressure, metabolic syndrome, obesity, and not exercising regularly. Specialized footwear helps prevent foot problems, and checking the feet every year is important for people with diabetes.

Lifestyle

See also: Diet in diabetes

People with diabetes can benefit from learning about the disease, making changes to their diet, and exercising. The aim is to keep blood sugar levels within a healthy range both now and in the future. Because diabetes can increase the risk of heart problems, changing lifestyle habits to control blood pressure is also recommended.

Losing weight can help prevent prediabetes from turning into diabetes type 2. It can also lower the risk of heart disease or even improve diabetes in some people. There isn’t one perfect diet for everyone with diabetes, but healthy diets like the Mediterranean diet, low-carbohydrate diet, or DASH diet are often suggested. For people with type 2 diabetes who have trouble keeping blood sugar under control, diets with fewer carbohydrates can be helpful. Any diet that helps someone who is overweight with type 2 diabetes lose weight can be effective.

In children

While type 1 diabetes is more common in children, type 2 diabetes is becoming more common, making up about a third of new cases. Risk factors include family history, not getting enough exercise, eating an unhealthy diet, and being overweight. Children with type 2 diabetes may face problems like high blood sugar, frequent urination, and feeling very thirsty. It’s important to recognize and treat diabetes early in children to avoid long-term complications.

Checking for type 2 diabetes usually starts at age 10 for children who are overweight and have at least two risk factors. Doctors look at blood tests to determine if a child has diabetes and may do more tests to tell apart type 1 and type 2 diabetes.

Treatment and management

Making healthy choices and using medicine like metformin are recommended to start with. Healthy habits include exercising for at least 60 minutes a day, limiting screen time, and learning about good nutrition.

Metformin, a medicine taken at 500 mg per day, is used when diabetes is first diagnosed. Insulin is used for children whose blood sugar is very high and whose HbA_1C is above a certain level.

Education

Managing diabetes in children works best when the family and healthcare team work together. The team may include a doctor who specializes in diabetes in children, a nurse who helps with diabetes, a dietitian, a psychologist, a social worker, and other specialists. The goal is to help the child learn to make healthy choices for a better life.

Medications

Glucose control

See also: Anti-diabetic medication

Most medicines for diabetes help by lowering blood sugar in different ways. Keeping blood sugar within a healthy range helps people with diabetes avoid problems like issues with the kidneys or eyes. However, there is some debate about whether this is the best approach for older people, because lowering blood sugar too much can sometimes cause problems.

There are many types of medicines for diabetes. People with type 1 diabetes need insulin, usually given in a mix of long-acting and quick-acting doses to copy the body’s natural insulin release. Type 2 diabetes is often first treated with oral medicines such as metformin, though some people later need insulin or other injections.

Metformin is usually the first medicine suggested for type 2 diabetes because it helps reduce the risk of serious problems. It works by lowering the amount of sugar made by the liver and helping the body use sugar better. Other medicines may also help lower blood sugar, such as those that increase insulin release, slow down sugar absorption, make the body more sensitive to insulin, or help the body get rid of sugar through urine. When insulin is needed in type 2 diabetes, a long-acting type is often added while continuing oral medicines.

In some serious cases of type 2 diabetes, insulin may be used, and the dose is increased until blood sugar levels are where they should be.

Blood pressure lowering

Cardiovascular disease is a serious concern for people with diabetes. Guidelines often suggest aiming for lower blood pressure targets than 140/90 mmHg, but there isn’t strong evidence to say exactly what the best target is. Some research shows that aiming for very low blood pressure might not be better and could cause problems.

Guidelines from 2015 suggest that people with diabetes who have kidney problems should take medicine to help protect their kidneys and heart. There is some evidence that certain medicines work better than others, but more recent research shows they may be similar.

Aspirin

Using aspirin to prevent heart problems in diabetes is not clear-cut. Some guidelines suggest low-dose aspirin for people at intermediate risk of heart disease, but others do not recommend it for everyone with diabetes.

Surgery

Weight loss surgery can be very helpful for people with obesity and type 2 diabetes. Many people are able to keep their blood sugar normal with little or no medicine after surgery, and they live longer. However, there is a small risk with the surgery itself. The exact weight levels that should qualify someone for this surgery are still being figured out. It is an option for those who can’t control their weight and blood sugar with other methods.

A pancreas transplant is sometimes an option for people with type 1 diabetes who have serious complications, especially if they also need a kidney transplant.

Self-management and support

In countries with a general practitioner system like the United Kingdom, care for diabetes often happens outside of hospitals, with hospital care only for complications or difficult cases. Using technology like home telehealth can help people manage their diabetes better. Programs using computers to teach adults with type 2 diabetes about managing their health have not shown clear benefits for things like cholesterol, blood pressure, exercise, or mood.

Epidemiology

Main article: Epidemiology of diabetes

Many people around the world have diabetes. In 2013, about 382 million people had it, up from 108 million in 1980. About 9 out of every 100 adults have diabetes, which is almost double the rate from 1980. Most of these cases are a type called type 2 diabetes.

Diabetes can affect people everywhere, but it is more common in richer countries. However, the number of cases is growing fast in poorer countries, especially in Asia and Africa. This increase is linked to changes in lifestyle, like less physical activity and eating more foods high in sugar and fat. By 2045, the number of people with diabetes may grow by almost half. In the United States, about 4 out of every 10 adults had a early stage of diabetes called prediabetes in 2020.

History

Main article: History of diabetes

Diabetes is one of the oldest known diseases. Ancient Egyptian writings from around 1500 BCE mention people having too much urine. Greek doctors later named this condition "diabetes," meaning "to pass through," because of the large amount of urine produced. Over time, different cultures noticed that the urine of people with diabetes was sweet.

It wasn't until the early 1900s that doctors found a way to treat diabetes. In 1921 and 1922, researchers in Canada discovered insulin, a substance that helps control blood sugar levels. This discovery changed how diabetes is treated and helped many people live better lives.

Society and culture

Further information: List of films featuring diabetes

In 1989, the "St. Vincent Declaration" was created to help improve care for people with diabetes. This is important because diabetes can affect quality of life, life expectancy, and use health resources.

Some countries have started programs to better treat diabetes, but these have had mixed success.

Diabetes stigma

Some people have negative feelings or unfair treatment toward individuals with diabetes. This can happen because some believe diabetes (especially Type 2) is caused by poor choices, though it can also be due to other factors. This stigma can affect people in many areas of life, including relationships, jobs, and social situations. People with diabetes may also feel negative about themselves, which can affect their health and interactions with doctors.

Inequalities in Diabetes

Certain groups face higher rates of diabetes. For example, Hispanic/Latino adults have a higher chance of developing Type 2 diabetes compared to others. African Americans are also more likely to be diagnosed with diabetes. Asians may develop diabetes at a younger age and with lower body weight. Many of these cases go undiagnosed.

People with diabetes who experience numbness or tingling in their feet or hands are more likely to face unemployment. In the United States, people from lower-income areas visit emergency rooms more often for diabetes-related issues than those from higher-income areas. Women often face extra challenges with diabetes, including mental health concerns and limited support. Transgender individuals also report difficulties in receiving proper care for diabetes.

Naming

Today, we use the terms "type 1 diabetes" and "type 2 diabetes" instead of older names like "juvenile diabetes" or "adult-onset diabetes." Sometimes diabetes is called "sugar diabetes" to distinguish it from a different condition called diabetes insipidus, which has similar symptoms but is not related.

Diabetes in other animals

Diabetes can happen in many animals, like mammals and some reptiles, but birds don’t get diabetes because their bodies handle high blood sugar better. Some signs in animals with diabetes can include drinking and urinating more, but sometimes these changes happen very slowly. Animals with diabetes might also get infections more easily. The ways to help animals with diabetes, like giving medicine and managing their weight, are similar to how doctors help humans. Some cat breeds, like the Burmese, Russian Blue, Abyssinian, and Norwegian Forest, and certain small dog breeds such as Miniature Poodles, are more likely to develop diabetes.