Ba-Ali S, et al. - Researchers carried out a cross-sectional, comparative study between June 2016 and March 2017 at the Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark to evaluate the function of rod/cones and melanopsin in T1DM and T2DM with and without non-proliferative diabetic retinopathy (NPDR). For this investigation, pupillometry was performed on 22 healthy controls and four diabetic groups: 12 T1DM patients without NPDR and 12 with moderate NPDR, and 16 T2DM patients without NPDR and 12 with moderate NPDR. The melanopsin-mediated late redilation phase of postillumination pupillary light response (PIPR_Late) to blue light was the primary outcome. The mixed rod/cone and melanopsin responses, that are maximal pupil constriction and the early redilation phase of PIPR (PIPR_Early), were the secondary outcomes. In diabetics with or without NPDR, neither PIPR_Early nor PIPR_Late was significantly reduced as compared with healthy controls. The reduced maximal constrictions of pupils in diabetics with NPDR suggest decreased response of mixed rod/cone and melanopsin.