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).