Background: Stroke is the second leading cause of death and disability worldwide. According to the World Health Organization report (2018), Mongolia has one of the highest stroke rates in the Western Pacific region and ranks second globally in stroke mortality and first in stroke-related disability. However, studies investigating the prevalence of diabetes mellitus (DM) among stroke patients in Mongolia remain limited. Aim: To determine the prevalence of diabetes mellitus among patients hospitalized due to ischemic stroke and to analyse the distribution of stroke subtypes. Materials and Methods: This retrospective study included patients with ischemic stroke who were admitted to the First and Third Central Hospitals of Mongolia within 24 hours after stroke symptom onset between 2024 and 2025. Data from 292 patients were analyzed. Demographic characteristics, stroke severity, time intervals, and laboratory findings were collected and compared between patients with and without diabetes mellitus. Result: The mean age of the study population was 61.9±12.9 years, and the majority of participants were male. Diabetes mellitus was present in 25% of the patients. The median duration of diabetes was 16 years (range 0–23 years), and the mean HbA1c level was 8.81±2.46%. There were no significant differences between diabetic and non-diabetic patients in terms of age, sex distribution, stroke severity, length of hospital stay, or in-hospital mortality. However, body mass index and glycemic parameters were significantly higher in patients with diabetes (p<0.001). According to the TOAST classification, small vessel disease was the most common stroke subtype, accounting for 57.3% of cases in patients with diabetes and 44.2% in patients without diabetes. Conclusion 1. Diabetes mellitus was present in one out of every four patients hospitalized with ischemic stroke. 2. Atherosclerotic stroke was six times more frequent in patients with diabetes compared with those without diabetes, highlighting the importance of early detection and management of diabetes in stroke prevention.