The purpose was to define the clinical peculiarities of bacterial keratitis in patients with type 1 diabetes mellitus (DM1) at visit 1. Methods. We retrospectively reviewed the results of 62 DM1 patients (62 eyes) with bacterial keratitis and 43 nondiabetic patients (43 eyes) with bacterial keratitis of the control group who were referred for visit 1 (before administering the treatment). Research methods were as follows: visual acuity, tonometry, slit-lamp biomicroscopy of anterior and posterior eye segments, bacteriological studies, fluorescein dye test, anterior eye OCT and non-contact corneal esthesiometry. Results. Compared to nondiabetic, DM1 patients with bacterial keratitis showed higher degree of inflammatory reaction in the anterior chamber of the eye at visit 1 (p<0.05) as well as 28.8% lower mean corneal sensitivity threshold (p<0.05). At visit 1, the degree of decreasing of corneal sensitivity in DM1 patients with bacterial keratitis was higher than in control group (p<0.05). Localization of bacterial keratitis, the degree of pericorneal injection, corneal ulcer defect size and depth, corneal infiltration as well as edema of the corneal tissue surrounding the ulcer did not depend on the presence of diabetes mellitus (р>0,05) at visit 1.Conclusions. There are clinical peculiarities of bacterial keratitis in patients with type 1 diabetes mellitus at visit 1.