Glaucoma, a leading cause of permanent blindness in the world, primarily affects older adults and is classified into four types, with diabetes mellitus potentially influencing the condition. The study aims to identify the link between Diabetes mellitus type two and Primary open angle Glaucoma. Subject and method A case-control study at Benghazi Educational Eye Hospital from December 2023 to February 2024. examined diabetic patients with and without glaucoma. Participants underwent ophthalmic examinations, including visual acuity, and gonioscopy. Patients with history of type two diabetes were included. The mean age of cases was significantly higher than controls [P=0.001]. There were significant differences in best corrected visual acuity between the two groups [P=0.035], Participants with high a [HbA1c] were more likely to have an advanced primary open angle glaucoma type. Participants with uncontrolled diabetes mellitus had higher intraocular pressure levels compared to the control group, [p=0.013]. There was a statistically significant difference in Retinal nerve fibers layers thickness in right eye, and Retinal nerve fibers layer thickness in left eye, between the case and control groups, [P= 0.041, 0.005 respectively. The age 66-75 years had a significantly higher risk of primary open angle glaucoma. A negative correlation between the duration of diabetes and Pattern standard deviation in left eye [ P = 0.051], as well as Visual Field left [P = 0.002]. The study reveals a significant link between diabetes mellitus type two and primary open angle glaucoma, with factors like higher intraocular pressure and older age causing higher incidence. early detection and management of risk factors could prevent or delay glaucoma onset.