AIM: To explore the factors that influence the pupil dilated in patients with type 2 diabetes mellitus.

METHODS: Totally 85 patients with type 2 diabetes were collected from April 2016 to August 2016 in department of Endocrinology in our hospital. Compound tropicamide was instilled in the right eyes of the 85 patients,then pupil diameters were measured 30min after instillation. They were divided into different groups according to the duration of diabetes, glycosylated hemoglobin levels, the degree of retinopathy and peripheral neuropathy. Influencing factors of the dilated pupil were analyzed.

RESULTS: In the three groups as the duration of diabetes was 5a, 5-10a or 10a or more respectively, the pupil diameters were 6.98±0.78mm, 6.18±0.67mm and 6.00±0.73mm, and the difference between the three groups was statistically significant(P<0.01). In non-proliferative diabetic retinopathy group, the pupil diameters(6.05±0.92mm)was significantly lower than that in the pre-clinical group(6.75±0.76mm), the difference between the two groups was statistically significant(P=0.001). The normal group of the ankle-knee conduction velocity(6.70±0.84mm)was significantly higherthan that in the abnormal group(6.23±0.81mm), and the difference was statistically significant between the two groups(P<0.05). In the three groups as the level of glycosylated hemoglobin was less than 8.4%, 8.4%～13.4% or more than 13.4%, pupil diameters were 6.60±0.82mm, 6.53±0.86mm and 6.73±0.73mm, the difference between the three groups was not statistically significant(P=0.708).

CONCLUSION: The main factors influencing the pupil are duration of diabetes, diabetic retinopathy and peripheral nerve lesions. In order to improve the effect of diabetes mellitus on the pupils, it is necessary to discover and treat the diabetic patients as early as possible. Diabetes patients with small pupil should more pay attention to the fundus examination, in order to avoid missed diagnosis of diabetic retinopathy.