Lipodystrophy at the insulin injection sites: current trends in epidemiology, diagnostics and prevention

Abstract

Lipodystrophy at the injection sites is most common local complication of insulin therapy. The history of its study started in 1926, when first cases of lipoatrophy at the sites of insulin injections were described. As we moved to human insulin and insulin analogues, immune mediated atrophic form of lipodystrophy has been replaced by hypertrophic one, which reflects anabolic and mitogenic effect of insulin. Lipohypertrophy at the injection sites is detected by physical examination in 40-70% of insulin-treated subjects. The detection efficiency depends on health care provider`s skills. Therefore, training of medical doctors and nurses in physical examination of injection sites seems to be reasonable. In recent years, ultrasound was introduced for diagnostics of insulin-induced lipohypertrophy. The method is more sensitive compared to palpation; ultrasound-verified lipohypertropthy was detected in more than 80% of cases. In patients with wide-spread lipohypertrophy ultrasound can be used to find suitable sites for injections (ultrasound injection map). Strain sonoelastography and 3D-power Doppler ultrasound can be used for quantitative estimation of rigidity and vascularization of lipohypertrophy. Both MRI and infrared images are considered as promising diagnostic tools. In a number of studies, it has been shown that the presence of lipohypertrophy is associated with high HbA1c levels, enhanced glycemic variability, unexplained hypoglycemia, and increased insulin doses. Thereby, lipohypertrophy aggravates the diabetes-related costs. The main risk factor for lipohypertrophy is inappropriate injection technique, including the lack of the site rotation, injections into lipodystrophic lesions, small injection area, reuse or excessive length of the needles. Accordingly, training patients in the injection technique is the basis for prevention of complication. The cessation of injections in lipohypertrophy areas and regular site rotation is essential for adequate titration of insulin dose and achievement of glycemic targets.