Diabetes mellitus is one of the most common diseases in the world. 2.8% of the world's population is affected by it; 10-20% of the affected individuals have type 1 diabetes mellitus and the remaining 80-90% suffers from type 2 diabetes mellitus. The white race is more commonly affected by the juvenile form, and men and women are equally affected.
Type 1 diabetes mellitus (T1DM) is characterised by an error in the body's immune system. Under normal conditions, our body defends itself against bacteria and viruses by activating the immune system; in juvenile diabetes, however, the immune system attacks and destroys the body's own pancreatic cells which produce and secrete insulin. Consequently, the body begins to lack insulin, glucose cannot enter the cells and it starts to accumulate in the blood. The exact cause of this is unknown. Hereditary and environmental factors play a role in the appearance of disease. Certain viral infections may trigger this disease in people with a genetic predisposition towards it. People with a family history of disease (affected parents, siblings) run a higher risk of developing type 1 diabetes mellitus.
The signs and symptoms of diabetes mellitus are the result of a disturbed glucose metabolism. The increased concentration of glucose binds water from cells and tissues, making patients thirsty all the time. They thus increase the intake of liquid and, as a result, urinate more frequently. Since there is no insulin in the circulating blood that would enable glucose obtained from food to enter the cells, the patients constantly crave food, even after a large meal. Although they eat more than usual, they may lose a lot of weight. Glucose derived from food cannot enter the energy-requiring cells due to the absence of insulin. The body starts to "import" energy from the glucose stores in the liver and muscles, and when these stores are depleted it starts using the fat stores. Due to the lack of energy, the patients feel fatigued. When blood glucose concentration reaches very high levels, glucose starts attracting water from the eye lenses. Consequently, visual disturbances may result.
If blood glucose is not adequately controlled, i.e. if it is either too high or too low, it can lead to multiple complications. The acute complications, requiring urgent medical attention, are the result of either a very high blood glucose concentration (i.e. hyperglycaemia), very low blood glucose concentration (hypoglycaemia) or increased burning of fats and production of harmful substances—ketones (ketoacidosis). Such patients may become unconscious or they may vomit, experience severe abdominal cramps, have fever or acetone breath.
Long-term complications appear after years of existing disease and affect various organ systems such as the blood vessels, the heart, kidneys, nerves and the eyes. The younger the patient's age at presentation and the wider the swings in blood glucose levels, the greater the risk of developing complications and the worse the disease prognosis.
With typical signs and symptoms in the patient's history, a physician suspects diabetes mellitus. Two blood samples are drawn in order to confirm the diagnosis—the first one in the morning (fasting state) and the second one at any time during the day, independent of the meal. The concentration of glucose is measured from the samples and the result either confirms the diagnosis of diabetes mellitus or rules it out. In order to differentiate between type 1 and type 2 diabetes mellitus, antibodies are sought in the blood—these are substances used by the malfunctioning immune system to destroy insulin-producing cells. Type 1 diabetes is characterised by the presence of such antibodies and a very low or absent insulin. The patient also gives a urine sample where ketones are measured—ketones are substances produced during fat metabolism. Type 1 diabetes patients have higher quantities of ketones in the urine. Due to the lack of insulin, energy from glucose cannot be utilised and fats are used as the source of energy.
It is currently impossible to prevent the appearance of T1DM. Research is currently underway into the options for prevention of this disease in people with the highest chance of developing it, such as children with a close relative (mother, father, brother, etc.) with T1DM.
Only when detection of the disease in the latent phase becomes possible will it be possible to employ the strategies to slow down the disease progression and its consequences. In other people, however, it is possible to suspect T1DM on the basis of signs and symptoms of disease such as thirst, hunger, weight loss and increased urination. The suspicion may be confirmed by determining the concentration of glucose in blood plasma. An early diagnosis and early start of treatment are important in order to prevent the acute and late complications of diabetes mellitus.
The goal of the therapy is to maintain the blood glucose concentration as close to normal values as possible. In this way, the development of the acute and chronic complications of diabetes mellitus may be halted or slowed down.
The concentration of blood glucose in T1DM patients may only be maintained as close to normal as possible with the use of insulin. Thus, the old name of this disease was the insulin-dependent diabetes mellitus. The insulin dose must be accurately determined and adjusted based on diet and physical activity. After a glucose-containing meal, the blood glucose level rises and more insulin is required. During physical activity, however, the blood glucose drops due to the increased entry of glucose into the muscles; thus, the patient requires less insulin.
Measurement of blood glucose is performed a few times a day in order to exercise a short-term control over therapy success; most importantly, however, it provides useful information for the determination of the right dose before insulin is injected. Measurements are carried out with portable measuring devices that require only a drop of blood obtained from the finger, and are thus very convenient.
Insulin represents the main part of therapy because patients with T1DM do not naturally produce enough insulin or they do not produce and secrete any at all. There are many insulin types that are classified according to their length of action. In therapy, various types are combined. Thus, the short-acting insulin is used to regulate the increased glucose concentration after the meals, while the long-acting insulin is used to maintain an adequate 24-hour insulin and glucose concentration, thus preventing the breakdown of fat reserves. They are usually administered by special pen injections that allow for a simple dosing of the required insulin amount, or by special insulin pumps that are carried around the belt and constantly provide a specific insulin quantity to which an additional quantity is added after the meals.
Adequate nutrition is also an essential part of therapy. Generally speaking, there are two basic approaches. In standard insulin therapy, the patient injects insulin two or three times a day according to a predetermined scheme and strictly adheres to a rigid dietary regime. It can be said that these patients eat because they have injected insulin. In the other approach, i.e. the intensified insulin therapy, the entire quantity to be injected daily is divided into two parts; the first dose (i.e. 40-50% of the daily dose) is used to cover the basic insulin requirements and is administered in the form of a single injection of a long-lasting insulin or two injections of an intermediate-lasting insulin. The rest of the daily dose (i.e. 60-50%) is administered in the form of meal-associated doses of the short-acting insulin. Simply put, these patients inject their insulin because they want to eat and not vice versa. The intensified therapy is associated with a 50% reduction in the rate at which the late complications appear as well as with a slowed progression of the already existent chronic changes.
Physical activity lowers the concentration of plasma glucose and increases the sensitivity of cells to insulin. This effect additionally protects from increases in blood glucose; thus, the patients are advised to engage primarily in aerobic exercise (fast walking, running, swimming, etc.) on most days of the week. However, the concentration of glucose may drop too drastically during exercise. Thus, it is important to adopt a conscientious and systematic approach towards devising an exercise plan (i.e. the frequency and intensity of exercise) by initially measuring glucose concentrations more often at times before, during and after physical activity, and adjust the meals and their composition, if possible under medical assistance.
New treatment option
New treatment options include an artificial pancreas which is still in the trial phase, devices for non-invasive glucose measurements and gene therapy which would involve re-programming of the liver cells to secrete insulin in relation to the blood glucose level.