During the last years the intensified insulin therapy has proven to be more successful than standard insulin treatment in patients with type I diabetes mellitus. For this kind of insulin therapy, intermediate and short acting insulin is injected in an independent manner. The basic need for insulin of the organism is covered with the intermediate insulin while application of the short acting insulin depends on carbohydrate intake and blood glucose levels. The patients are learning the intensified insulin therapy by structured guidance that they are able to modify the insulin dosage by themselves. The patients have to take several parameters into account to calculate the actual insulin need such as physical activity, interval between meal and injection, infectious diseases, or the circadian rhythm. An intensified insulin therapy involves a great deal of time for the patient since he has to perform insulin injections and measurements of blood glucose levels up to four times a day. However, this kind of treatment increases the flexibility of the patient's food intake and metabolic control which reduces the onset of diabetic side effects.