Type 1 diabetes


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PantherMedia / Dmitrii Kiselev

Diabetes is a metabolic disease that affects many parts of the body. Depending on the type of diabetes, the body either cannot produce insulin itself (type 1) or is unable to use the insulin it produces properly (type 2). Insulin is a hormone – a chemical messenger that is transported in the blood and regulates important body functions. Without insulin your body cannot get the energy it needs from the food you have eaten.

This vital hormone is usually produced in the pancreas and released into the bloodstream. Here it enables the sugar (glucose) in our food and drink to be transported into our cells and converted into energy for our bodies. Without insulin our bodies cannot use the sugar in our blood, so the sugar builds up there. Very high blood sugar concentrations cause a number of symptoms.

People with type 1 diabetes have to inject insulin on a daily basis because their can only produce insulin in very small quantities, or can’t produce any insulin at all. Insulin therapy helps prevent strong fluctuations in blood sugar levels and the unpleasant effects of high and low blood sugar. It is also intended to prevent complications that may arise as a result of high blood sugar levels.

Illustration: Insulin molecules and position of the pancreas

Insulin molecules and position of the pancreas


They might not always notice it at first. But very high blood sugar (hyperglycemia) can cause the following problems:

  • Frequent urination
  • Extreme thirst
  • Tiredness and listlessness
  • Nausea
  • Dizziness

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

Causes and risk factors

Insulin is produced in cells in the pancreas known as beta cells. In people who have type 1 diabetes, the beta cells are attacked by their own immune system. Over the years these cells become so damaged that they only produce very little insulin, or none at all.

Type 1 diabetes is more common in certain families. This means that some people have a higher risk of developing diabetes because of their genes. Other things are believed to play a role too, for example particular infections or environmental factors. But it is not clear what exact role they play. 

Prevalence and outlook

About 200,000 people in Germany have type 1 diabetes. About 30,000 of them are children and teenagers under the age of 19. Every year about 2 out of 10,000 children develop type 1 diabetes.

Because it usually starts in children, teenagers or young adults – and only rarely in older people – type 1 diabetes is also called “juvenile” (young) diabetes.

If left untreated, type 1 diabetes can soon lead to problems. Very high blood sugar causes typical symptoms like thirst, frequent urination and . These symptoms can quickly be relieved with insulin. Diabetic coma due to extremely high blood sugar levels is very rare nowadays. Before insulin therapy was introduced in 1922, it was an unavoidable consequence of the disease, leading to death. As a result, people who developed type 1 diabetes did not live long.


Blood sugar levels that are very high over many years can have serious and irreversible health consequences. The complications and damage arising from poorly controlled diabetes may affect many organs. The small blood vessels that supply the tissue become damaged.

Over time, the tiny blood vessels in, for instance, the retina of the eye (diabetic retinopathy) or kidneys (diabetic nephropathy) can become so damaged that the person affected might go blind or have kidney failure. Another common diabetes-related problem is known as diabetic neuropathy, which attacks the nerves. It affects the sense of touch and the perception of temperature and pain. This can lead to the development of wounds because people might not notice sore areas and small injuries. These wounds often don't heal well because of the poor blood supply. 


To find out whether someone has diabetes, their blood sugar levels are measured before their first meal of the day and then again during the day. Several samples of blood are taken in a doctor’s practice and sent to a laboratory to be tested. To see whether someone’s blood sugar levels have been too high over a longer period of time, something known as the HbA1c value is measured. This value indicates how high your blood sugar has been on average in the last two to three months.


In type 1 diabetes, the focus of treatment is to monitor blood sugar levels every day and regularly use insulin. Insulin therapy makes up for the lack of insulin in the body and lowers the concentration of sugar in the blood. It is important to avoid using too much or too little insulin, to prevent blood sugar levels from getting too low or too high. Treatment also aims to prevent long-term complications associated with diabetes as much as possible. There are different types of insulin and different treatment approaches.

Blood sugar levels are not only affected by the amount of insulin you inject but also by what you eat and drink, as well as how much energy you use during physical activity. The time of day, inflammatory diseases, other medications or hormonal changes can influence your blood sugar levels too. So most people learn to finely adjust their insulin therapy according to their own body and personal habits.

In order for treatment to be successful, people need to be well informed about their diabetes, manage their own therapy and have reliable medical care. But over the long term, your general health will depend on other things besides just blood sugar levels. Aspects like blood pressure can have a big effect in diabetes. Because of this, people with diabetes often take other medications as well, for example to prevent cardiovascular disease.

Everyday life

Although there is currently no cure for diabetes, it is possible to lead an almost normal life with the disease. There were times when people with diabetes had to lead strictly regulated lives. For example, they had to wait a certain amount of time between injecting insulin, eating and doing physical activity. These rules have relaxed a lot since then. Insulin therapy has become much more flexible.

Nowadays, people who have diabetes can largely decide for themselves what kind of treatment they would like and how to fit it into their daily lives. Diabetes no longer dominates all aspects of their lives.

But managing diabetes still requires a good deal of effort, care and discipline. That isn't always easy and can sometimes be quite a burden, especially for younger people. Just like most people who have a chronic condition and have to take medication every day, those with diabetes might forget to inject insulin or take their medication every now and then. People who do not follow their treatment plan properly often feel quite normal and do not necessarily notice that their blood sugar levels are poorly controlled. But this can lead to serious health problems in the long term.

Deutsche Diabetes Gesellschaft e.V. (DDG). Diagnostik, Therapie und Verlaufskontrolle des Diabetes mellitus im Kindes- und Jugendalter. S3-Leitlinie. October 2015. (AWMF-Leitlinien; volume 057 - 016).

Deutsche Diabetes Gesellschaft e.V. (DDG). Therapie des Typ-1-Diabetes. S3-Leitlinie. September 2011. (AWMF-Leitlinien; volume 057 - 013).

Leelarathna L, Guzder R, Muralidhara K, Evans ML. Diabetes: glycaemic control in type 1. BMJ Clin Evid 2011.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Updated on June 29, 2017
Next planned update: 2021


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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