Diabetes mellitus is a metabolic disorder characterized by hyperglycemia. It is often associated with complications, such as cataracts and increased susceptibility to frequent and protracted infections. High glucose levels induce oxidative stress in immune system cells, both in vitro and in vivo, as well as an increase in their Nuclear Factor-kappa B activity. A study conducted by Muriach M and co-workers demonstrated that lutein treatment of lymphocytes from diabetic rats inhibited oxidative stress and reduced the Nuclear Factor-kappa B activity . They concluded that lutein is a potential candidate for the reduction of susceptibility to infections of diabetic patients.
Diabetes patients have an increased risk of cataract, leading cause of blindness characterized by cloudiness or opacity of the eye lens. Many scientific studies have focused on the protective effect of lutein against the development of cataract. A Spanish team lead by Arnal E found that a combined treatment with lutein and insulin prevented the development of cataracts in streptozotocin-induced diabetic rats . Lutein and insuline, alone or in combination, significantly inhibited lipid peroxidation in the diabetic lens. Only a combination of insulin and lutein prevented the diabetes-induced decrease of glutathione content.
 Lutein prevents the effect of high glucose levels on immune system cells in vivo and in vitro. J Physiol Biochem. 2008 Jun;64(2):149-57.
 Lutein prevents cataract development and progression in diabetic rats. Graefes Arch Clin Exp Ophthalmol. 2009 Jan;247(1):115-20.