Yanli Guo,1,* Dinggui Huang,2,* Jingxia Sun,3,* Zhenwei Zhai,3,* Hewei Xiao,4,* Weiguang Hao,5 Qiu Wang,3 Jianhao Huang,3 Miaomiao Jin,1 Wensheng Lu3,* 

1Department of Endocrinology, Heji Affiliated Hospital of Changzhi Medical College, Changzhi, Shanxi, 046011, People’s Republic of China; 2Project Fund Supervision Center, Health Commission of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, 530021, People’s Republic of China; 3Department of Endocrinology and Metabolism, Guangxi Academy of Medical Sciences, People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, 530021, People’s Republic of China; 4Scientific Research Cooperation Department, Guangxi Academy of Medical Sciences, People’s Hospital of Guangxi Zhuang Autonomous Region, Nanning, Guangxi, 530021, People’s Republic of China; 5Department of Endocrinology, Tongde Hospital, Yuncheng, Shanxi, 044000, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Wensheng Lu, Department of Endocrinology and Metabolism, Guangxi Academy of Medical Sciences and the People’s Hospital of Guangxi Zhuang Autonomous Region, No. 6, Taoyuan Road, Nanning, Guangxi, 530021, People’s Republic of China, Email Lwswxqz@163.com

Aim: This study aimed to assess the efficacy of antithyroid drugs (ATDs) and radioactive iodine-131 (RAI) therapies in reducing the risk of major adverse cardiovascular events (MACEs) and all-cause mortality in patients with hyperthyroidism complicated with type 2 diabetes mellitus (T2DM).
Methods: Between January 2013 and December 2021, 540 subjects were included in the analysis. All participants were followed up for 9 years, with a median of 54 months (2451 person-years). The subjects were categorized into two groups: the ATDs group (n = 414) and the RAI group (n = 126). According to the free triiodothyronine (FT3) tertiles, the patients receiving RAI were further grouped as follows: low-level (≤ 4.70 pmol/L, n = 42), moderate-level (4.70– 12.98 pmol/L, n = 42), and high-level (≥ 12.98 pmol/L, n = 42). The efficacy of ATDs and RAI therapies in reducing the risk of MACEs and all-cause mortality was assessed.
Results: Of the 540 participants, 163 experienced MACEs (30.19%), 25 (15.34%) of whom died. Multivariate Cox regression analyses revealed that RAI was associated with a 38.5% lower risk of MACEs (P = 0.016) and a 77.1% lower risk of all-cause mortality (P = 0.046). Stratified analyses indicated that RAI had a protective effect on MACEs in patients aged ≥ 60 years (P = 0.001, P for interaction = 0.031) and patients with a duration of diabetes mellitus ≥ 6 years (P = 0.013, P for interaction = 0.002). Kaplan‒Meier analysis revealed a lower cumulative incidence of MACEs and all-cause mortality in the RAI group (log-rank, all P < 0.05). Moreover, the ROC curve suggested an optimal FT3 cut-off value of 5.4 pmol/mL for MACE (P < 0.001).
Conclusion: Our findings suggested that RAI therapy effectively reduced the risk of MACEs and all-cause mortality in elderly patients with hyperthyroidism combined with T2DM.

Keywords: hyperthyroidism, type 2 diabetes mellitus, radioactive iodine-131, major adverse cardiovascular events, all-cause mortality