The Distinct Ultrasound Characteristics and Prognostic Features of Insulin-Induced Lipohypertrophy: A Systematic Review.

Background: Insulin-induced lipohypertrophy (LH) is a common complication of insulin therapy. However, its ultrasound characteristics, classification, and progression patterns remain poorly understood. This review aimed to systematically analyze the ultrasound characteristics and progression patterns of LH, and explore the relationship between different LH types and clinical outcomes.

Methods: A systematic literature search was conducted from January 2000 to October 2024 in PubMed, Web of Science, Embase, and Cochrane Library following PRISMA guidelines. Studies that examined LH using ultrasound in diabetic patients receiving insulin therapy were included. Two independent reviewers performed study selection and quality assessment using standardized tools.

Results: Twenty studies involving 5067 patients were included. Ultrasound showed significantly higher detection rates (57.6-100%) than physical examination (27.9-79.7%), with subclinical LH reported in 13.0-55% of cases. Twelve studies provided detailed ultrasound characteristics, with most describing well-defined borders, echo patterns predominantly showed hyper-echogenicity, and noted reduced or absent blood flow. Two ultrasound patterns were identified based on nodule size and echo patterns. Follow-up studies demonstrated distinct progression patterns and varying metabolic improvements among different LH types.

Conclusion: Ultrasound reveals three distinct patterns (nodular, diffuse, and hypoechoic), each with unique prognostic features, providing a basis for individualized management.