Objective To investigate the risk factors for the severity of leukoaraiosis (LA) in patients aged ≥80 years and analyze the characteristics of LA in the diabetic patients. Methods Totally 202 patients aged≥80 years who were identified with LA by head MRI in the Third Affiliated Hospital of Anhui Medical University were recruited in this study. The severity of LA was assessed according to the rating scale for age-related white matter changes (ARWMC). The clinical baseline data were compared among the patients with different severities of LA. According to glycosylated hemoglobin A1c (HbA1c) at admission, the diabetic patients were further divided into 3 subgroups, and their clinical features were compared. SPSS statistics 22.0 was used to perform the statistical analysis. One-way ANONA, Chi-square test and rank sum test was employed for different data types. Related risk factors for LA were analyzed with logistic regression analysis. Results As the severity of LA increased, the age showed an increasing trend, the prevalence of diabetes was elevated, and the fasting blood glucose level was increased, statistical differences were seen among the three groups (P<0.05). The ARWMC score was obviously higher in the diabetic group than the non-diabetic group [6.00 (4.00,8.00) vs 4.00 (3.00,6.00), P<0.001]. Multinomial regression analysis found that age and HbA1c level were independent risk factors for LA severity in diabetic mellitus group. Conclusion In the very old patients with LA, age and diabetes are correlated with LA severity. In the elderly diabetic patients with LA, HbA1c level is independently correlated with LA severity.