Effect of Empagliflozin on Serum Levels of Thyroid Hormones Among Prediabetic and Diabetic Patients

<b>Objectives:</b> Thyroid dysfunction (TD) and diabetes mellitus (DM) are the most prevalent chronic endocrine disorders that often coexist. Thyroid hormone affects glucose homeostasis through different mechanisms. SGLT2 inhibitors are a drug class used to treat diabetes. However, the effect of this drug class on thyroid tests has not been investigated among diabetic patients. Therefore, the current study aims to assess the effect of empagliflozin on thyroid tests. <b>Materials and Methods:</b> This quasi-experimental study was conducted on 44 prediabetic and type 2 diabetic patients aged 18-65, directed to the clinic affiliated to Kerman Medical Sciences University in 2022-2023. Diabetic patients with HbA1c level of 0.5%-1% higher than the therapeutic target, who did not take blood sugar control drugs, were included in the study. All the patients received 10 mg of empagliflozin once daily for 3 months. Before and 3 months after taking empagliflozin, changes in TSH, total T4, and total T3 serum levels were measured. <b>Results:</b> The mean patients' age was 54.77 years old. The mean FBS and HbA1c levels decreased 3 months after taking empagliflozin (<i>p</i> < 0.05). After taking empagliflozin, T3 level as well as T3/T4 ratio increased (<i>p</i>=0.001). However, no significant change was observed in T4 and TSH levels (<i>p</i> > 0.05). Also, level of T3 significantly changed with changes in weight and triglyceride level after taking empagliflozin. <b>Conclusion:</b> The results showed taking empagliflozin could increase T3 level as well as T3/T4 ratio. However, it had no effect on total T4 and TSH levels. <b>Trial Registration:</b> Iranian Registry of Clinical Trials (IRCT): IRCT20090317001774N10.