Subclinical Hypothyroidism and Diabetes: Exploring ECG Alterations and Cardiovascular Risks

Abstract

Background: Subclinical hypothyroidism (SCH) is associated with subtle but significant alterations in cardiac function, which can be further exacerbated by coexisting diabetes mellitus. These changes, often reflected in electrocardiographic (ECG) parameters, provide insights into the autonomic dysfunction and arrhythmic risks in these patients. This study investigates ECG changes in SCH and explores the impact of diabetes on autonomic modulation.

Methods: A retrospective study was conducted on 90 adult patients divided into three groups: Group A (SCH without diabetes), Group B (SCH with diabetes), and Group C (controls with normal thyroid function and no diabetes). Comprehensive ECG analysis, including heart rate variability (HRV), QT interval, and T-wave morphology, was performed to evaluate autonomic modulation and cardiac function. Statistical comparisons were made using ANOVA and post-hoc tests.

Results: SCH patients exhibited significant ECG changes, including prolonged QT intervals and reduced HRV, indicative of impaired autonomic modulation. These abnormalities were more pronounced in Group B, with higher QTc dispersion (Group B: 52.1 ± 5.3 ms vs. Group A: 47.8 ± 4.9 ms, p < 0.01). HRV parameters, including SDNN and RMSSD, were significantly lower in diabetic SCH patients, suggesting heightened sympathetic dominance.

Conclusion: Subclinical hypothyroidism is associated with autonomic dysfunction reflected in ECG changes, which are exacerbated by coexisting diabetes. These findings highlight the need for early detection and management of SCH, particularly in diabetic patients, to mitigate cardiac risks.