As known insulin therapy is associated with induration of subcutaneous fat at injections sites called lypohypertrophy. It develops at any age and at anysite regardless of duration of the treatment. The size of lypohypertrophy varies in a wide range. Numerous studies have been conducted to elucidatemechanisms of lypohypertrophy (LH) and its risk factors including young age, low or high body mass index, frequency of the change of needles andinjection sites, female gender, and type 1 diabetes mellitus. It was shown that insulin crystals induce a local immune reaction and thereby interfere withadipocyte differentiation. At the same time, patients with LH have elevated titters of anti-insulin antibodies. The problem with LH is uncontrollableabsorption of insulin from injection sites. We noticed that patients with a target glucose level due to insulin therapy undergo its apparently causelessperiodic rises. Comparative ultrasonic examination of subcutaneous fat at different injection sites and control body areas revealed specific pathologicalchanges in adipose issue. This finding provided a basis for the hypothesis that LH can be detected by ultrasonography of subcutaneous fat. It wasconfirmed by the results of examination of 50 patients with DM1 treated with insulin of whom 41 were found to have pathological changes at injectionsites.