Objective To record and analyze the changes in the ocular surface and cornea in diabetic patients using a battery of ophthalmic tests and high resolution laser scanning confocal microscopy. Methods Prospective case control study. One hundred and eight patients with type 2 diabetes and 33 normal people (controls) were enrolled in this study. Based on the classification stages of diabetic retinopathy, patients were divided into 2 groups, those 42 patients (59 eyes) with non-diabetic retinopathy (NDR) and 66 patients (86 eyes) with proliferative diabetic retinopathy (PDR). All patients were examined using corneal sensitivity measurements, Schirmer's I test,non-invasive tear film break-up time (BUT), and corneal fluorescein staining. The testing regime also included DR-1 tear film interferometer camera and corneal confocal microscopy examinations.Parameters among groups were analyzed with a one-way ANOVA, a chi-square test and Spearman's rank correlation analysis. Results There was a significant difference between the NDR group (32％ were equal to or greater than grade Ⅲ) and the control group (14％) in the tear film test (P＜0.01). Corneal sensitivity was significantly lower in the PDR group [(33.0±12.4)mm] than in the control group [(47.2±9.7)mm] (P＜0.01). Tear secretion was (11.8±4.2)mm in the PDR group, and (15.2 ±4.3)mm in the control group. The difference between the two groups was statistically significant (P＜0.01). Tear film BUT was significantly shorter in the diabetic group [(7.3±2.5)s] than in the control group [(13.7±4.0)s] (P＜0.01). There was a sgnificant difference between the PDR group (50％ were equal to or gerater than grade Ⅲ) and the control group (14％) in the tear tim test (P＜0.01). Seventy-four percent patients were positive in PDR group in corneal fluorescein staining, much higher than control group (8％) (P＜0.01). Densities of corneal epithelium and corneal nerve fiber were all significantly lower in the PDR group [(4407±480)/mm2, (898±153)μm/field] than in the control group [(4736±313)/mm2, (1231±