Insulin Prevents Latent Skin Lesions by Inhibiting the Generation of Advanced Glycation End Products in Streptozotocin-Induced Diabetic Rats

The preventive effect of insulin on latent skin lesions in streptozotocin-induced diabetic rats was investigated. Diabetes was induced in 72 male Sprague-Dawley rats, with 36 rats serving as the control group. Half of the diabetic rats were treated with insulin, and the other half were injected with vehicle. Skin tissues were collected 4, 8, and 12 weeks after the initiation of insulin therapy for measurement of glucose, collagen-related fluorescence and advanced glycation end product (AGE) expression, and histological observation. The diabetic rats exhibited changes in skin tissue, including a decrease in thickness, disappearance of the multilayer epithelium structure, degeneration of collagen fibers, and an increase in the infiltration of inflammatory cells, in addition to a significant increase in blood glucose and AGE expression. These effects were greatly ameliorated by insulin therapy. Insulin therapy in early-stage diabetes mellitus prevents potential skin lesions, possibly by inhibiting AGE formation and inflammatory reactions following glycemic control.