Abstract:Objective To analyze the clinicopathological features of papillary thyroid carcinoma (PTC) with type 2 diabetes mellitus (T2DM) and their clinical relevance. Methods A total of 130 patients who underwent thyroidectomy and were confirmed with PTC by histopathologic examination in the Affiliated Hospital of Southwest Medical University from September 2015 to December 2019 were selected in the retrospective analysis, among which 65 PTC patients with T2DM were enrolled as the study group and 65 cases without T2DM were enrolled as the control group. Thyroid function, tumor size, multifocality ( ≥ 2), capsular invasion, extrathyroidal extension, comorbidity with benign thyroid nodules or Hashimoto’s thyroiditis, and cervical lymph node metastasis were compared between the two groups. Results Compared to the control group, the patients in the study group showed lower levels of free triiodothyronine (P < 0.05), and the lesions were more inclined to present multifocality, capsular invasion, extrathyroidal extension and lateral cervical lymph node metastasis (P < 0.05). Conclusions The PTC patient with T2DM shows lower level of free triiodothyronine, and the tumor seems more likely to be multifocal, with capsular invasion, extrathyroidal extension and lateral cervical lymph node metastasis, compared to PTC patient without T2DM.