Insulin-Induced Lipohypertrophy: Insights From the Italian Care Model—diagnosis, Progression, Clinical Impact, Current Challenges, Future Perspectives, and the Rehabilitative Role of Education

Insulin-induced skin lipohypertrophy (LH) represents a highly prevalent yet frequently neglected localized complication of subcutaneous insulin therapy. Drawing extensively from the highly structured, three-tiered Italian diabetes care model, this comprehensive narrative review evaluates the current literature on the diagnostic criteria, prevalence, clinical consequences, pathogenesis, and treatment of LH. The Italian framework—characterized by a widespread network of territorial specialist centers (Second Level care)—provides unique real-world data on this phenomenon. Diagnosis of LH relies heavily on structured clinical examination and skin ultrasound, facilitated by specialized outpatient settings. Morphologically, LH disrupts insulin pharmacokinetics, precipitating erratic absorption, unexplained severe hypoglycemia, and extreme glycemic variability. These clinical events impose a massive economic burden on acute hospital care (Third Level). A global epidemic of injection errors highlights an alarming deficit in injection technique knowledge, not only among patients but also among healthcare professionals. Prevention and treatment hinge on strict adherence to proper injection techniques and the transition to ultra-thin 3.5mm/34G needles, which significantly reduce penetration force and improve patient adherence. However, technological advancement alone is insufficient: continuous, multimodal therapeutic educational rehabilitation—a core mandate of Italian territorial diabetes centers—is essential to regress LH lesions and restore metabolic control. Addressing these unmet needs globally requires updating international guidelines, such as the upcoming 2025 recommendations, while looking to the Italian integrated care model as a benchmark for the systemic implementation of standardized training.