Show main content

What is type 1 diabetes?

Scientific support: Prof. Dr. Carolin Daniel

With type 1 diabetes, the body is unable to produce enough or any of the essential hormone insulin. Without insulin, the cells in the body cannot absorb the sugar from food. The blood glucose level rises – with serious health consequences.

Type 1 diabetes cannot currently be cured. People with type 1 diabetes have to take insulin for the rest of their lives, either by injection or an insulin pump.

Type 1 diabetes is the most common metabolic disease in children. The disease usually starts in puberty, between the ages of 10 and 15. This form of diabetes therefore used to also be called juvenile diabetes. However, the disease can manifest at any age.

Type 1 diabetes: an autoimmune disease

Unlike type 2 diabetes, personal lifestyle, overweight or lack of exercise are irrelevant in the development of type 1 diabetes. It is an autoimmune disease where the misdirected immune system destroys the cells in the own body that produce insulin. Insulin is produced by beta cells. These are in what are called the islets of Langerhans, specific areas of cells in the pancreas. Beta cells account for 65 to 85 percent of the islets of Langerhans. This is why they are often referred to as islet cells.

The pancreas is an organ located in the upper abdominal region behind the stomach. It releases various substances into the intestine or directly into the blood and therefore plays a role in the digestion of food. 

Insulin is an essential hormone, i.e. a messenger substance that is released by the beta cells into the bloodstream. Severe metabolic disorders can develop without insulin. The amount of glucose in the blood rises. 

Click here to find out more about the processes in the body and the development of type 1 diabetes.

What are the typical signs of type 1 diabetes?

Typical signs of type 1 diabetes are:

  • Feeling very thirsty
  • Increased urination
  • Weight loss
  • Muscle weakness
  • Tiredness and exhaustion
  • Poor wound healing
  • Dry skin
  • Visual impairment

With type 1 diabetes these symptoms can develop within just a few weeks or even days. The growing hyperglycemia in the body can trigger a serious metabolic imbalance relatively quickly and without warning. This is know as diabetic ketoacidosis. This manifests with acidification of the body, which can trigger typical symptoms, such as   

  • Abdominal pain 
  • Vomiting 
  • Nausea
  • Deep labored breathing 
  • Foul-smelling breath or urine 
  • Brain fog and loss of consciousness through to coma

If diabetes is suspected, a medical laboratory test will generally clarify the situation quite quickly. Typical changes in the blood panel and urine are:

  • Elevated blood glucose levels (hyperglycemia)
  • Increased level of glucose in urine (glucosuria)
  • Acidification of the blood caused by a buildup of ketones (Ketoacidosis)

Good to know:

Personal lifestyle has nothing to do with the development of type 1 diabetes. Type 1 diabetes is an autoimmune disease

Diabetes can result in a range of complications. A high level of glucose in the blood damages the small and large blood vessels and the nerves. This can have an effect on many organs. Regular medical checkups are therefore important. This particularly concerns the eyes, kidneys, brain, cardiovascular system and the feet. Nerve damage can lead to reduced perception of pain, such as not noticing small injuries on the feet. In unfavorable cases, wounds may develop that do not heal well.

What are the possible complications of type 1 diabetes and how can they be prevented?

After every meal, the food is broken down into its components for digestion. The most important substances are protein, fat and carbohydrates. Foods such as bread, pasta, rice or potatoes are largely made up of carbohydrates. Carbohydrates are broken down in the digestive system into small sugar components. These are called glucose.

Glucose is the most important energy supplier to the body. After eating there is a large amount of glucose in the blood, and the blood glucose level rises. The pancreas measures the glucose content in the blood at all times. If the values increase, this prompts the release of the hormone insulin into the blood.

A hormone is a messenger substance produced by the body, which sends messages between difference cells in the body. Insulin is tasked with delivering glucose into the cells of the body. The blood transports the insulin to the cells in the body, the muscles and the brain. Insulin acts like a key, allowing the glucose in the food to pass through into the cells in the body. The cells need glucose as a source of energy.

Diabetic ketoacidosis mainly manifests in people with type 1 diabetes. It develops when the blood glucose level is sharply increased because there is not enough insulin. If there is too little insulin, the glucose in the blood cannot enter the cells in the body – so they are then missing energy for the metabolic processes. The body then begins to break down fatty tissue to meet its energy needs. The fat is broken down into fatty acids and these are then incompletely broken down into what are known as ketone bodies. The elevated concentration of ketone bodies leads to dangerous acidification of the blood. The symptoms of ketoacidosis include the following:

  • Dry mouth
  • Dry skin
  • Severe nausea with vomiting
  • Abdominal pain
  • Breath that smells of acetone (like the smell of nail varnish or spoiled fruit)
  • Deep breathing (Kussmaul breathing)
  • Severe fatigue / sleepiness
  • Thirst
  • Frequent urination (polyuria)
  • Nighttime urination (nocturia)
  • Feeling of weakness
  • Drowsiness
  • Confusion
  • Visual impairment

Untreated, ketoacidosis can lead to diabetic coma, a complex metabolic imbalance with loss of consciousness and acute threat to life for the patient. diabetic ketoacidosis must be treated in hospital, and usually on the intensive care ward.

People with diabetes who consistently have blood glucose levels exceeding 240 mg/dl (13.3 mmol/l) should test the ketone content of their urine with a ketone test strip.

If the test shows ketone bodies in the urine (Ketonuria), the patient should drink plenty and avoid physical activity as much as possible. If the ketonuria does not resolve in the next 8 hours, the person must see a doctor immediately. This prevents a ketoacidosis metabolic imbalance.


Danne, T. et al. (2014): Diabetes bei Kindern und Jugendlichen. 7. Auflage. Springer Verlag, Heidelberg, ISBN: 978-3-642-24645-6
Fayfman, M. et al.: Management of Hyperglycemic Crises: Diabetic Ketoacidosis and Hyperglycemic Hyperosmolar State. In: Med Clin North Am, 2017, 101: 587-606
Häring, H.-U. et al. (2011): Diabetologie in Klinik und Praxis. 6. Auflage. Georg Thieme Verlag KG, ISBN: 9783135128061
Umpierrez, G. et al.: Diabetic emergencies — ketoacidosis, hyperglycaemic hyperosmolar state and hypoglycaemia. In: Nat Rev Endocrinol, 2016, 12: 222-232
As of: 26.10.2019