Changes in connective tissue against the background of hyperglycemia in patients with type 1 diabetes mellitus is a morphological substrate for the formation of diabetic complications. The presence of undifferentiated connective tissue dysplasia in a patient with absolute insulin deficiency, the prevalence of individual external manifestations of which among young people is 85.4%, can increase the risk of developing and progressing complications of diabetes mellitus. The purpose of the review is to summarize the literature data on the impact of undifferentiated connective tissue dysplasia on the course of type 1 diabetes mellitus and its complications when they are combined in one patient. An analysis of the literature has shown that today there are single studies that have studied the specifics of the course of type 1 diabetes mellitus and its complications against the background of undifferentiated connective tissue dysplasia, with some aspects analyzed in children and adolescents, others in adults, which does not allow to draw clear conclusions. The results of these studies demonstrated earlier development and progression of such diabetic complications as nephropathy, neuropathy, post-injection lipodystrophy in patients with increased dysplastic stigma. According to some experts, patients with type 1 diabetes mellitus and concomitant undifferentiated connective tissue dysplasia should be allocated to a separate group of dispensary observation, since they may have a higher risk of developing and progressing rate of chronic complications of diabetes mellitus, which leads to a concomitant decrease in quality of life and increased risk of disability. However, to date, the question of the influence of increased dysplastic stigmatization on the course of type 1 diabetes mellitus has not been fully studied.