Increased risk of diabetes mellitus and hyperlipidemia in patients with differentiated thyroid cancer.

Objective: This study aimed to assess the risk of cardiometabolic disease (CMD) in patients with differentiated thyroid cancer (DTC) using a population-based nationwide cohort in Korea.

Design: This was a population-based cohort study.

Methods: We selected 2649 patients with DTC and 7947 matched controls. The primary outcome was the composite of CMD including diabetes mellitus (DM), hypertension, hyperlipidemia, cerebrovascular disease, and ischemic heart disease. The secondary outcomes were each individual type of CMD, all-cause mortality, and CMD-specific mortality. The cause-specific hazard ratios (HRs) for each outcome were estimated based on cause-specific Cox proportional hazard regression models.

Results: Patients with DTC had an 11% higher risk of the primary composite outcome than controls (HR, 1.11; 95% confidence interval [CI], 1.04-1.19). The risks of DM (HR, 1.22; 95% CI, 1.08-1.38) and hyperlipidemia (HR, 1.36; 95% CI, 1.24-1.48) were higher in patients with DTC. In contrast, the risk of CMD-specific mortality was lower in those with DTC (HR, 0.24; 95% CI, 0.09-0.68). A nonlinear, U-shaped relationship was observed between the daily dose of levothyroxine and the risk of DM (P = .021), but the risk of hyperlipidemia was low with high doses of levothyroxine in patients with DTC (P = .003).

Conclusions: Patients with DTC had an increased risk of CMD, especially DM and hyperlipidemia, but a low risk of CMD mortality. Special attention to metabolic diseases is required in the long-term follow-up of patients with DTC.