IL31 and diabetes mellitus: Although the involvement of IL-31 in diabetes is not known, IL-31 was detected in both the serum and vitreous samples of PDR patients (76% and 58.6%, respectively), and the percent detectable and level in the vitreous fluid of PDR patients were significantly higher than those in patients with ERM or MH, suggesting a possible role of IL-31 in the pathogenesis of diabetes.