A study is underway to determine the effects of topical insulin on tear inflammatory mediators interleukin-1a, interleukin-6 and matrix metalloproteinase-9 in people with diabetes and DED.90 A trial with topical insulin has demonstrated significant and similar improvement in the OSDI score as artificial tears; however, long-term studies in a larger patient population are required to confirm the efficacy and safety of topical insulin.91 This evidence concerns the gene INS and diabetes mellitus.