Background: Diabetes mellitus is a heterogeneous metabolic disorder characterized by hyperglycemia. It is often associated with complications, such as cataracts. Cataract, characterized by cloudiness or opacity of the eye lens, is the leading cause of blindness worldwide.
Methods: The present study investigated the effect of lutein, alone or combined with insulin on the progression of eye lens opacities in streptozotocin-diabetic rats for a period of 12 weeks. Tissue markers of oxidative stress were also determined at the end of the experiment.
Results: Herein we demonstrate that lutein treatment prevents the development and progression of cataracts (0 eyes with mature cataract, and ten out of 16 eyes with clear lenses in the lutein-treated diabetic animals group, vs. seven and three eyes in the non-treated diabetic group, respectively). Lipid peroxidation is significantly increased in diabetic lens (up to three-fold); lutein and insulin, alone or in combination, are able to prevent this alteration. Only insulin and lutein together could prevent the diabetes-induced decrease of glutathione content.
Conclusions: The combined treatment with lutein and insulin is useful in preventing the development of cataracts in streptozotocin-induced diabetic rats, supporting its utility in diabetes management, especially when a tight metabolic control is difficult to achieve.