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Overview: Type 2 diabetes

Last Update: December 18, 2023; Next update: 2026.


Type 2 diabetes is a metabolic disorder that causes your blood sugar levels to increase. The severity of diabetes can vary quite a bit: Some people get the disease well under control, and in others it leads to more health problems over time.

There are two main types of diabetes: Type 1 diabetes usually develops in childhood or the teenage years. This disease is a result of damage to the pancreas that leaves it producing either very little insulin or none at all.

Things are different in type 2 diabetes, where insulin is made by the pancreas but the body’s cells gradually lose the ability to absorb and use the insulin. In the past, type 2 diabetes was often referred to as “adult-onset” diabetes because it is commonly diagnosed later in life. Type 2 diabetes is much more common than type 1 diabetes. About 90% of people who have diabetes have type 2 diabetes.

At a glance

  • Type 2 diabetes usually develops in the second half of life.
  • This condition increases your blood sugar levels.
  • Getting more exercise and changing your diet can sometimes already make a big enough difference.
  • If that isn't effective enough, treatment with tablets or insulin injections is considered.
  • The possible long-term effects of diabetes include problems with the heart, kidneys, eyes or feet.


If type 2 diabetes goes untreated, blood sugar levels stay high all the time. Type 2 diabetes can develop gradually over several years without any noticeable symptoms, so the diagnosis often comes as a surprise. Having high blood sugar levels for months or years eventually causes the following symptoms, though:

  • Extreme thirst
  • Frequent urination
  • Tiredness, fatigue and lack of drive
  • Trouble concentrating
  • Nausea
  • Dizziness
  • Erection problems

If someone has extremely high blood sugar levels, they may feel confused and drowsy or even lose consciousness (diabetic coma).


Our metabolism makes sure that the sugar (glucose) in our food is distributed evenly throughout the body, so all of our organs get enough. One of the things that is needed for this process to work properly is a hormone known as insulin. It is made by the pancreas. After you eat something, the sugar levels in your blood rise and insulin is released into your bloodstream. Insulin allows cells to absorb sugar from the blood, for instance in the liver and muscle tissue. If insulin stops having this effect, the body can no longer use the sugar in the blood properly. This leads to an increase in the amount of sugar in the blood. The medical term for blood sugar levels that are too high is hyperglycemia.

In people who have type 2 diabetes, the pancreas actually produces enough insulin, but it no longer has an effect on the body's organs. This is what doctors refer to as “insulin resistance.” The pancreas can compensate for this for a while by producing more insulin. But at some point it can no longer keep up, and then blood sugar levels start to rise.

Risk factors

Various factors can increase the likelihood of developing type 2 diabetes:

  • Being overweight and not getting enough physical exercise
  • Smoking
  • A low-fiber, high-fat and sugary diet
  • Certain medications that affect the body’s sugar metabolism
  • Genetic factors: Type 2 diabetes is more common in some families


People who have type 2 diabetes are at greater risk of developing the following health problems:

  • Cardiovascular (heart and blood vessel) diseases: These include heart attacks, strokes and problems with the circulation in their legs and feet (peripheral arterial disease, PAD). Complications like this are known as macrovascular complications. “Macrovascular” means that they affect the larger blood vessels. The risk of developing them is especially high in people who also have high blood pressure.
  • Damage to the eyes, nerves and kidneys: These are microvascular complications of diabetes. “Microvascular” means that the smaller blood vessels are affected. This can make your eyesight get worse over time. Health problems caused by microvascular damage are more common in people who develop type 2 diabetes at a fairly young age – for instance, around the age of 50. People who develop diabetes in older age are less likely to have these problems.
  • Diabetic foot: Here the nerve damage in the foot is so severe that pain can hardly be felt at all there. The legs and feet have a poor blood supply too. Then things like blisters and bruises can easily lead to wounds that don't heal well. If a wound isn't treated soon enough, some of the tissue may die.


If your doctor thinks you might have type 2 diabetes, he or she will first ask about any symptoms and other conditions that you may have. You will then also have a physical examination and your blood sugar levels will be measured. To check your blood sugar levels before your first meal and over the course of a day, several blood samples are taken and then analyzed in a laboratory. The HbA1c value is also measured: This value is a measure of the average blood sugar levels over the last two to three months.

If blood sugar levels are high enough to be causing typical diabetes symptoms, sugar can usually be detected in urine (pee) as well. You can measure the level of sugar in your urine with easy-to-use test strips. These are available from pharmacies and doctor's practices in Germany and many other countries.


There’s a lot of advice out there about how to prevent type 2 diabetes. It mainly concerns lifestyle factors such as eating a balanced diet, getting enough exercise, and keeping your weight down as a result.

People who have a higher risk of diabetes can, in fact, delay the onset of diabetes for a number of years by changing their diet and getting more exercise. But it's not clear whether eating the "right" foods and getting more physical exercise can help you prevent type 2 diabetes completely.


A number of factors influence which treatment approach for type 2 diabetes is suitable: They include other health problems, age, life circumstances and personal goals.

  • Lifestyle changes: Losing weight and getting more exercise can lower your blood sugar levels. Quitting smoking helps to reduce the risk of cardiovascular (heart and blood vessel) disease. Some people manage to get their diabetes under control simply by changing these kinds of habits.
  • Medication: Many people need medication to regulate their blood sugar levels. Some take tablets, and others inject insulin. It is also possible to use a combination of tablets and injections.
  • Surgery: If very overweight (obese) people find it hard to lose weight, surgical approaches such as stomach stapling may be an option.
  • Treating other health problems: A lot of people who have type 2 diabetes also have other health problems, such as high blood pressure or high cholesterol. Treating those problems helps to reduce the risk of cardiovascular disease too.

Everyday life

People with type 2 diabetes can do various things themselves to help them get by without medication. The most important thing is to lose at least a little weight by changing your diet – even though that may be difficult to do in practice. Getting more physical exercise (for example, by walking regularly) can have a positive effect too.

That's not always enough, though. You can then consider medication that has to be used regularly over a long period of time. It can take a while to get used to the idea of using medication for the rest of your life – especially if you don’t feel ill and don’t notice any immediate benefits. But knowing all about diabetes can make dealing with the condition a normal part of your daily routine and help you maintain a high quality of life.

Further information

The key to managing diabetes is understanding your body and the disease, and knowing what you can do for your health yourself. You can get help here – for instance, from doctors and other healthcare professionals, including nurses, diabetes consultants, diet consultants, and foot specialists (podiatrists).

There are also a wide range of different services that offer individual advice and support if you are ill. These include support groups. Many of the offers vary greatly, depending on where they are based, and they aren’t always easy to find. Our list of points of contact can help you to find and make use of local offers in Germany.

You can also take part in a “disease management program” (DMP) provided by your statutory health insurer. Here diabetes specialists offer patient education, advice and comprehensive medical care. They help you to manage the disease and treatment in everyday life.


© IQWiG (Institute for Quality and Efficiency in Health Care)
Bookshelf ID: NBK279509


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