AIM: To determine the risk factors and time to non-arteric ischemic optic neuropathy (NAION) occurrence among Thai type 2 diabetes mellitus (T2DM) patients. METHODS: A retrospective review of 266 newly diagnosed T2DM cases at Rajavithi Hospital between 2007 and 2016 was conducted to determine time to occurrence of NAION and evaluate associated risk factors. RESULTS: Hypertension and dyslipidemia were the most common pre-existing vascular diseases and there was a significant male predominance in the NAION group. The mean age of the NAION group was significantly higher than that of the group without NAION. A higher proportion of subjects in the NAION group had hypertension, dyslipidemia, high diastolic blood pressure, smokers, and had a small cup-to-disc ratio (CDR). Higher levels of triglycerides and low-density lipoprotein-cholesterol in the group with NAION. Fifty-five patients among 266 participants (20.68%) developed NAION during a mean follow-up time of 81.26±25.04mo. In a multivariable logistic regression analysis, dyslipidemia (OR=8.36, 95%CI, 3.447-20.273, CONCLUSION: T2DM patients with dyslipidemia or a small CDR should be carefully followed up as they are at increased risk of developing NAION.