Effect of levothyroxine therapy on albuminuria and glomerular function in patients with type 2 diabetes and subclinical Hypothyroidism: a randomized controlled pilot trial.
AIMS: To evaluate the effect of levothyroxine therapy on renal outcomes in patients with type 2 diabetes mellitus (T2DM) and subclinical hypothyroidism (SCH) with background SGLT2 inhibitor therapy. METHODS: In this hypothesis generating open-label, randomized controlled pilot trial, adults with T2DM and SCH were assigned (1:1) to levothyroxine or no levothyroxine therapy and followed for 6 months. Primary outcomes were changes in urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR). RESULTS: Sixty participants were randomized (30 per group); 24 and 27 completed follow-up in the treatment and control groups respectively. UACR decreased with levothyroxine (-13.09 mg/g) and increased in controls (31.84 mg/g). The difference was significant in per-protocol (PP)(-44.93 mg/g; 95% CI -77.6 to -12.26; p = 0.008) but insignificant in intention to treat (ITT)(-35.61 mg/g; 95% CI -77.31 to 6.08; p = 0.092). eGFR changes were statistically insignificant in both ITT(4.65 mL/min/1.73 m2; 95% CI -8.3 to 17.6; p = 0.472) and PP(7.35 mL/min/1.73 m2; 95% CI -1.68 to 16.37; p = 0.108). Thyroid-stimulating hormone decreased significantly in treatment arm in comparison to control arm (p < 0.001) in ITT and PP. No adverse event was reported. CONCLUSIONS: Levothyroxine treatment showed trend toward improving albuminuria and eGFR without reaching statistical significance, suggesting possible renoprotective effect warranting further studies. CLINICAL TRIAL REGISTRATION: This trial is registered with Clinical Trial Registry of India (CTRI/2025/06/089606).