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Diabetes mellitus


Diabetes mellitus (diabetes) is a group of metabolic diseases based on insulin resistance or insulin deficiency which lead to increased glucose levels in the blood (hyperglycemia). The classification diabetes mellitus distinguishes four forms, with type 1 diabetes (primarily insulin-dependent) and type 2 diabetes (not primarily insulin-dependent) being the most common forms of the disease. Type 3 is composed of secondary diabetes, LADA and MODY diabetes. Type 4 refers to gestational diabetes (GDM).

Normal blood sugar levels when fasting are under 100 milligrams per deciliter. After eating, that amount may increase to a maximum of 140 milligrams per deciliter. Blood sugar levels which are above this may indicate the existence of diabetes.


In its initial stage diabetes can proceed without outward symptoms, even over longer periods of time. But with a significant increase in blood sugar, clinically observable symptoms can occur in both type 1 and type 2 diabetes. These include, among others, polyuria and nocturia, excessive thirst, loss of appetite and resulting weight loss, susceptibility to infections, fatigue and apathy, headaches, blurred vision and muscle cramps.

The symptoms associated with type 1 diabetes can develop within a few days or weeks, and are characterized primarily by rapid weight loss and extreme polydipsia, which may result in extreme cases in loss of consciousness or a diabetic coma.

The symptoms of type 2 diabetes develop more slowly over a longer period. They may go unnoticed at the beginning, or express in non-specific symptoms such as increased thirst or fatigue and susceptibility to infections, among others. This can also lead to complications such as impaired wound healing, retinopathy or polyneuropathy.

Causes and Risks

The causes of diabetes vary according to the type of the disease, however all are dependent on insulin (insulin resistance or insulin deficiency). Insulin is a hormone produced in the pancreas which is needed to accomplish the absorption and conversion of glucose in the cells. If this absorption is impeded, the concentration of glucose in the blood increases, which in turn leads to cell damage. In type 1 diabetes, the body's own antibodies destroy the pancreatic cells that produce insulin. Insulin production will thus be significantly affected, up to its complete cessation. The reasons why the organism produces antibodies are largely unknown, but there is evidence for genetic factors. Type 2 diabetes involves insulin resistance, in which the cells need considerably more insulin to cope with the glucose uptake from the blood. This leads to increased secretion of insulin which results in an overload of the pancreatic cells and then a decrease in insulin production.

Examination and Diagnosis

A diagnosis of diabetes mellitus is based on determining the blood sugar level (fasting and postprandial) and the urine sugar. The normal level of blood sugar in a fasting state is a maximum of 100 milligrams per deciliter. Additional diagnosis is possible through the oral glucose tolerance test (OGTT) and determination of the C-peptide and the A1C (long-term blood sugar). The affected person is said to be diabetic if elevated blood sugar levels were measured on at least two different days. Following the diagnosis, the levels in the ocular fundus, blood and kidney  should be determined as well as the patient's blood pressure and urine.


The treatment of diabetes depends on the type of the disease, but in principle a change in diet, physical exercise and sports are important components of the therapy concept. Drug therapy for type 1 diabetes ranges from conventional insulin therapy (CT) through intensified conventional therapy (ICT) to continuous subcutaneous insulin infusion therapy (CSII, insulin pump).

In the treatment of type 2 diabetes, oral anti-diabetics (OAD), hypoglycemic medications, or their combination with conventional insulin therapy (CT), intensified conventional insulin therapy (ICT) or insulin pump therapy, are employed.

Course and Prognosis

With optimal therapy and proper adjustment of the blood glucose levels, the prognosis and life expectancy with diabetes mellitus is considered relatively good, although certain complications and secondary diseases can occur in diabetics. Among others, diabetic retinopathy, diabetic nephropathy and related neuropathy and atherosclerosis can often develop. In addition, the risk of myocardial infarction, stroke and heart failure increases many times among those affected.

While preventive measures in the traditional sense are hardly possible with type 1 diabetes, as this is an autoimmune form of the diabetes disease, with type 2 diabetes a proper and balanced diet and exercise can be effective not only from a therapeutic perspective, but also in prevention.