Brief overview
- Symptoms: intense thirst, increased urination, weight loss, dizziness, nausea, weakness, in extreme cases, impaired consciousness or even unconsciousness
- Causes: Autoimmune disease (antibodies destroy insulin-producing beta cells in the pancreas); gene mutations and other factors (such as infections) are thought to be involved in the development of the disease
- Investigations: Measurement of blood glucose and HbA1c, oral glucose tolerance test (oGTT), screening test for autoantibodies.
- Treatment: Insulin therapy
- Prognosis: Treated, usually favorable prognosis with slightly reduced life expectancy; without treatment: risk of complications and life-threatening course
What is diabetes type 1?
Type 1 diabetes is a form of diabetes mellitus in which the body is barely or not at all able to produce the insulin necessary for sugar metabolism. As a result, the sugar (glucose) is not available to the cells, but remains in the blood, resulting in a constantly elevated blood sugar level.
What are the symptoms of type 1 diabetes?
People with type 1 diabetes are usually slim (unlike type 2 diabetics). They typically show severe thirst (polydipsia) and increased urine output (polyuria). The trigger for these two symptoms is the greatly elevated blood glucose level.
Many sufferers experience weight loss, fatigue and lack of drive. In addition, dizziness and nausea sometimes occur.
When blood glucose levels are very elevated, diabetes type 1 patients develop impaired consciousness. Sometimes they even fall into a coma.
You can read more about the symptoms and consequences of diabetes mellitus in the article Diabetes mellitus – symptoms and consequences.
What causes type 1 diabetes?
In type 1 diabetes, the body’s own antibodies destroy the insulin-producing beta cells (islet of Langerhans cells) of the pancreas. Type 1 diabetes is therefore a so-called autoimmune disease.
Why the immune system attacks the beta cells of the pancreas in people with type 1 diabetes mellitus has not yet been precisely clarified. Scientists suspect that genes and other influencing factors such as infections with certain pathogens play a role in the development of type 1 diabetes.
Genetic causes
According to current medical guidelines, around ten percent of type 1 diabetes patients have a first-degree relative (father, sister, etc.) who also has diabetes. This suggests a genetic predisposition. Researchers have already identified several gene mutations that are associated with the development of type 1 diabetes. As a rule, several gene alterations are present that together lead to type 1 diabetes mellitus.
A group of genes located almost exclusively on chromosome six appears to have a particularly strong influence: The so-called human leukocyte antigen system (HLA system) has a significant influence on the control of the immune system. Certain HLA constellations such as HLA-DR3 and HLA-DR4 are associated with an increased risk of type 1 diabetes.
Other influencing factors
Experts suspect that various external factors also influence the development of type 1 diabetes. In this context, researchers discuss:
- A too short breastfeeding period after birth
- A too early administration of cow’s milk to children
- A too early use of gluten-containing food
- Toxins such as nitrosamines
It is also possible that infectious diseases cause or at least promote immune system dysfunction in type 1 diabetes. Suspected infectious diseases include mumps, measles, rubella, and infections with Coxsackie viruses or the Epstein-Barr virus.
It is also striking that diabetes mellitus type 1 often occurs together with other autoimmune diseases. These include, for example, Hashimoto’s thyroiditis, gluten intolerance (celiac disease), Addison’s disease, and autoimmune gastritis (type A gastritis).
Finally, there is also evidence that damaged nerve cells in the pancreas are involved in the onset of type 1 diabetes.
Type 1 special form: LADA diabetes
As in “classic” type 1 diabetes, diabetes-specific autoantibodies can be detected in the blood in LADA – but only one specific type (usually glutamic acid decarboxylase antibodies = GADA), whereas type 1 diabetics normally have at least two different types of diabetes antibodies. These are, for example, autoantibodies against insulin (AAI), against islet cells (ICA), or precisely against glutamic acid decarboxylase (GADA).
Another common feature with type 1 diabetes is that LADA patients are usually rather slim.
However, while type 1 diabetes almost always appears in childhood and adolescence, LADA patients are usually older than 35 years at diagnosis. This is similar to type 2 diabetes, where the age of onset is usually after the age of 40.
In addition, LADA patients, like type 2 diabetics, often show evidence of metabolic syndrome. This is characterized by lipid metabolism disorders and high blood pressure, for example.
Because of the various overlaps, LADA patients are often diagnosed with type 1 or type 2 diabetes. Some consider LADA to be a hybrid of both main types of diabetes. However, physicians now tend to believe that LADA is caused by both types of diabetes at the same time and develops in parallel. The causes of LADA have not been conclusively determined.
Idiopathic diabetes type 1
Idiopathic diabetes type 1 is very rare. Patients have a permanent insulin deficiency but have no detectable autoantibodies. Their body or blood tends to become repeatedly hyperacidic (ketoacidosis). This form of diabetes is highly heritable and occurs predominantly in people of Asian or African descent.
Detect diabetes type 1
Tests for type 1 diabetes
The interview is followed by a physical examination. The doctor will also ask for a urine sample and make an appointment with you for a blood sample. This must be done on an empty stomach. This means that in the eight hours before the (morning) blood sample is taken, the patient must not eat anything and must consume at most unsweetened, calorie-free drinks (such as water). Sometimes an oral glucose tolerance test (oGTT) is useful.
You can read more about these tests in the article Diabetes testing.
Detection of autoantibodies
To distinguish between type 1 and type 2 diabetes, for example, the doctor tests the blood for typical autoantibodies. These are those that are directed against various structures of the beta cells:
- Islet cell antibodies (ICA)
- Antibodies against the glutamate decarboxylase of the beta cells (GADA)
- antibodies against tyrosine phosphatase
- antibodies against the zinc transporter of the beta cells
In particular, children with type 1 diabetes often also have antibodies against insulin.
Diabetes type 1 stages
The Juvenile Diabetes Research Foundation (JDRF) and the American Diabetes Association (ADA) already speak of diabetes type 1 when the patient does not yet have any symptoms but does have antibodies in the blood. They distinguish between three stages of the disease:
- Stage 1: The patient has at least two different autoantibodies
- Stage 2: Blood glucose levels (fasting or after eating) are elevated (“prediabetes”)
- Stage 3: Hyperglycemia is present
How to treat diabetes type 1?
Type 1 diabetes is based on an absolute insulin deficiency, which is why patients are dependent on injecting insulin for the rest of their lives. Generally, doctors recommend human insulin and insulin analogues. They can be administered with a syringe or (usually) a so-called insulin pen. The latter is an injection device that resembles a fountain pen. Some patients use an insulin pump that continuously delivers insulin to the body.
For type 1 diabetes patients, a thorough understanding of the disease and insulin use is very important. For this reason, every patient usually receives special diabetes training immediately after diagnosis.
In a diabetes training course, patients learn more about the causes, symptoms, consequences and treatment of type 1 diabetes. They learn how to measure blood glucose correctly and administer an insulin injection themselves. Patients also receive tips for living with type 1 diabetes, for example with regard to sport and diet. Since exercise lowers blood glucose levels, doctors advise patients to monitor their blood glucose levels closely and practice adjusting their insulin and sugar intake correctly.
With regard to nutrition, patients learn, for example, how much insulin the body needs when and for which foods. The decisive factor here is the proportion of usable carbohydrates in a food. This influences the amount of insulin that needs to be injected.
The so-called carbohydrate unit (KHE or KE) plays an important role here. It corresponds to ten grams of carbohydrate and increases the blood glucose level by about 30 to 40 milligrams per deciliter (mg/dL). Instead of the carbohydrate unit, medicine used to primarily use the so-called bread unit (BE). One BE corresponds to twelve grams of carbohydrates.
Doctors also recommend attending diabetes training for caregivers in institutions that type 1 diabetics visit. These are, for example, teachers or educators at a daycare center.
Conventional insulin therapy
In conventional insulin therapy, patients inject themselves with insulin according to a fixed schedule: insulin is injected two or three times a day at fixed times and in fixed doses.
One advantage of this fixed regimen is that it is easy to apply and particularly suitable for patients with limited learning or memory skills. Another advantage is that it does not require constant blood glucose measurements.
On the other hand, this fixed regimen leaves patients relatively little room for maneuver, for example if they want to change their meal plan spontaneously. A relatively rigid lifestyle is therefore required. In addition, blood glucose cannot be adjusted as uniformly with conventional insulin therapy as is possible with intensified insulin therapy. Consequential damage to diabetes mellitus is therefore more likely with this regimen than with intensified insulin therapy.
As part of intensified insulin therapy, patients usually inject a long-acting insulin once or twice a day. It covers the fasting insulin requirement, which is why doctors also call it basic insulin (basal insulin). Immediately before a meal, the patient measures his or her current blood glucose level and then injects a normal insulin or a short-acting insulin (bolus insulin). The dose depends on the previously measured blood glucose value, the carbohydrate content of the planned meal and planned activities.
The basic bolus principle requires good cooperation from the patient (adherence). In fact, blood glucose is measured several times a day to avoid hyperglycemia or hypoglycemia. This requires a small prick in the finger. The drop of blood that emerges is analyzed for its sugar content using a measuring device.
A major advantage of intensified insulin therapy is that the patient is free to choose the food as well as the amount of exercise. The dose of bolus insulin is adjusted accordingly. Provided that the blood glucose levels are permanently well adjusted, the risk of secondary diseases is considerably reduced.
However, blood glucose measurements by the patient are still necessary because there is a physiological difference between tissue and blood glucose.
Insulin pump
A diabetes pump is often used, especially for young diabetics (type 1). This is a programmable, battery-operated small insulin dosing device that the patient carries with him at all times in a small pocket, for example on his belt. The insulin pump is connected via a thin tube (catheter) to a fine needle inserted in the subcutaneous fatty tissue on the abdomen.
The pump delivers small amounts of insulin to the body throughout the day according to its programming. They cover the basic daily requirement (fasting requirement) of insulin. At mealtimes, a freely selectable amount of bolus insulin can be injected at the touch of a button. The patient must first calculate this amount. This takes into account the current blood glucose level (measured in advance), the planned meal and the time of day.
The insulin pump gives children in particular a great deal of freedom. The diabetes pump can also be disconnected briefly if necessary (for example, for showering). However, the pump should always be worn during sports. Many patients report that their quality of life has improved significantly thanks to the insulin pump.
Basically, the pump remains on the body at all times, even at night. However, if the catheter becomes clogged or kinks unnoticed, or if the device malfunctions, this interrupts the insulin supply. There is then a risk that dangerous hyperglycemia and subsequently hyperacidity (diabetic ketoacidosis) will quickly develop. In addition, insulin pump therapy is more expensive than intensified insulin therapy.
Continuous glucose monitoring (CGM) can also be combined with an insulin pump. The glucose sensor, which is inserted in the subcutaneous fatty tissue, transmits the tissue glucose readings directly to the pump and warns of possible hyperglycemia or hypoglycemia. Doctors refer to this as sensor-assisted insulin pump therapy (SuP). Regular blood glucose measurements are still necessary in this case.
Insulins
Few diabetics use animal insulin from pigs or cattle – mostly due to an intolerance to the preparations described above. However, this is no longer produced in Germany and must be imported.
Insulins can be classified according to their onset and duration of action. For example, there are short-acting and long-acting insulins.
You can read the most important facts about the different insulin preparations in the article Insulin.
Is type 1 diabetes curable?
Type 1 diabetes is an autoimmune disease that lasts a lifetime and currently has no cure. However, some scientists believe that sometime in the future type 1 diabetes will be curable. They have been researching various therapeutic approaches for years – so far without a breakthrough.
Since the causes are not clearly known and genetic factors are mostly behind the disease, there is no way to prevent it efficiently. As far as pathogens that are considered risk factors for type 1 diabetes are concerned, the risk can be reduced, if necessary, by appropriate vaccination.
Life expectancy
Complications
In the context of type 1 diabetes, some people experience various complications. These include acute life-threatening conditions (hypoglycemia, ketoacidotic coma) and long-term consequences of diabetes. They are more likely to be avoided the better a patient’s blood glucose levels are controlled.
Low blood sugar (hypoglycemia)
The most common complication of type 1 diabetes is hypoglycemia (low blood sugar) caused by incorrect insulin calculation. It is usually manifested by symptoms such as dizziness, weakness, nausea and trembling of the hands, as well as cramps, palpitations and sweating. Missing a meal or extensive exercise also cause hypoglycemia if the therapy is inadequately adjusted.
Hypoglycemia should not be underestimated. In the case of severe hypoglycemia, for example, there is an undersupply of blood to the brain, which leads to unconsciousness. In this case, the emergency physician must be informed immediately!
Ketoacidotic coma
One of the most feared complications of type 1 diabetes is ketoacidotic coma. Sometimes diabetes mellitus is not noticed until the onset of this condition, which occurs as follows:
When these are metabolized, acidic degradation products (ketone bodies) are produced. They cause hyperacidity of the blood (acidosis). The body exhales a certain amount of acid in the form of carbon dioxide through the lungs. Affected type 1 diabetes patients therefore exhibit extremely deep breathing, known as kissing-mouth breathing. The breath often smells of vinegar or nail polish remover.
At the same time, the lack of insulin in type 1 diabetes sometimes raises blood glucose levels to the high hundreds. The body reacts to this with increased urine excretion: it excretes excess glucose together with large amounts of fluid from the blood via the kidneys. As a result, it begins to dehydrate.
The severe loss of fluid and the acidification of the blood may be accompanied by a loss of consciousness. This makes the ketoacidotic coma an absolute emergency! Patients must receive immediate intensive medical treatment. In case of suspicion, the emergency physician should therefore always be alerted.
You can read more about this metabolic derailment in our article “Diabetic ketoacidosis”.
Consequential diseases of type 1 diabetes
In the kidneys, the vascular damage triggers diabetic nephropathy (diabetes-related kidney damage). If the retinal vessels are damaged, diabetic retinopathy is present. Other possible consequences of diabetes-related vascular damage include coronary heart disease (CHD), stroke, and peripheral arterial disease (PAVD).
Over time, the excessively high blood glucose levels in poorly controlled type 1 (or 2) diabetes also damage nerves (diabetic polyneuropathy) and lead to serious functional disorders. The most common complication in this context is diabetic foot syndrome. It is usually accompanied by persistent wounds (ulcers) that heal with difficulty.
Depending on the course of the disease and the success of treatment, diabetes mellitus can lead to severe disability if complications occur. It is therefore all the more important to start diabetes therapy as early as possible and to carry it out consistently.
You can read more about possible complications of diabetes in the article Diabetes mellitus.