Cardiovascular Effects of Cumulative Doses of Radioiodine in Differentiated Thyroid Cancer Patients with Type 2 Diabetes Mellitus

SIMPLE SUMMARY: The cardiovascular effects of radioiodine ((131)I) therapy on people with differentiated thyroid cancer (DTC) and concomitant type 2 diabetes mellitus (T2DM) are unknown. To the best of our knowledge, this study is the first of its kind. Our aim was to assess the relationship between the left ventricular ejection fraction (LVEF) and high cumulative (131)I doses in DTC/−T2DM and DTC/+T2DM female patients. In the DTC/−T2DM group, LVEF was negatively associated with high cumulative doses of (131)I. This association did not exist in patients with DTC/+T2DM. ABSTRACT: Radioiodine ((131)I) therapy for differentiated thyroid cancer (DTC) involves exposure of the whole body, including the heart, to ionizing radiation. This exposure to the subsequent risk of heart disease is uncertain, especially in patients with DTC associated with type 2 diabetes mellitus (DTC/+T2DM). The current study aimed to assess the relationship between left ventricular ejection fraction (LVEF), high cumulative (131)I dose, and peripheral blood parameters in patients with DTC/−T2DM and DTC/+T2DM. The study enrolled 72 female patients with DTC/−T2DM and 24 with DTC/+T2DM who received cumulative (131)I doses above 150 mCi (5.55 GBq). LVEF was lower in patients with concomitant T2DM than those without (p < 0.001). The cumulative (131)I dosage was inversely correlated with LVEF only in DTC/−T2DM patients (r = −0.57, p < 0.001). In the DTC/+T2DM group, LVEF was negatively associated with absolute platelet count (r = −0.67, p < 0.001) and platelet-to-lymphocyte ratio (r = −0.76, p < 0.001). Our results demonstrate that exposure to high cumulative (131)I doses has different cardiovascular effects in DTC/−T2DM and DTC/+T2DM.