Background: The clinicopathological characteristics of patients with papillary thyroid carcinoma (PTC) combined with type 2 diabetes mellitus (T2DM) and patients with PTC alone were explored and compared in order to provide a more reasonable treatment plan for the clinical diagnosis and treatment of these patients. Methods: A total of 1,771 patients from January 2017 to December 2019 who underwent PTC surgery for the first time in the west branch of the Fourth Hospital of Hebei Medical University were analyzed retrospectively. Among them, 111 patients had PTC with T2DM (D-T group) and 1,660 patients had PTC alone (PTC group). The differences in general data and clinical characteristics between the D-T group and the PTC group were analyzed. Results: There were statistically significant differences in age, gender, and body mass index (BMI) between the D-T group and PTC group (P<0.05). Multifocality and extra-glandular invasion in the D-T group were significantly higher than the PTC group (P<0.05). In women, the D-T group was older, had a higher BMI, and was more likely to have extra-glandular invasion (P<0.05) than the PTC group. The prognosis of the D-T group was worse than that of the PTC group as determined by 3 well-developed prognostic staging systems, 8th AJCC TNM staging, MAGIS SCORE, AMES staging, and the results were statistically significant (P=0.001, P<0.001, P=0.021). Conclusions: Our study showed that the overall prognosis of PTC patients with T2DM was worse than that of patients with PTC alone. At the same time, especially in patients younger than 55 years of age, multifocal carcinoma and extra-glandular invasion are likely to occur. In addition, female patients with T2DM are more likely to have extra-glandular invasion than male patients. Therefore, for such patients, preoperative evaluation should be fully conducted.