Objective To investigate the prevalence of thyroid nodules in elderly patients (age≥80 years) with type 2 diabetes mellitus (T2DM), and to analyze the correlation between thyroid nodules and type 2 diabetes mellitus. Methods The study included two groups: one group included 103 patients with T2DM (diabetic group) and the other group included 103 patients without T2DM (control group). Information including clinical history, fasting plasma glucose(FPG), thyroid hormone, and ultrasonic finding of thyroid glands was collected for both groups. The clinical features of thyroid nodules were compared between the two groups and their relationship with other indices was analyzed. Results (1)The prevalence rate of thyroid nodules in diabetic group was greatly higher than that of the control group (84.47% vs 70.59%). The proportion of patients with multiple nodules was as high as 80.46% in the diabetic group. Presence of thyroid nodule was significantly associated with patient ages (χ²=7.060, P<0.05), but not with gender, body mass index (BMI), or serum glucose level. (2) The positive rate of thyroid dysfunction in the diabetic group was significantly higher than that in the control group (15.53% vs 6.80%, P<0.05). The prevalence rates of sub-clinical hypothyroidism were similar between the two groups. T₃ and T₄ levels of thyroid function in the diabetic group were significantly lower than those in the control group (P<0.05), and the thyroid stimulating hormone (TSH) levels were similar between the two groups. Conclusion Elderly patients (age≥80 years) have a higher liability for thyroid disease, which may affect the control and prognosis of diabetes. It is recommended for those patients to receive regular check-up for thyroid function and morphology changes.