Objective: To investigate the expression levels of serum melatonin and 5-hydroxytryptamine in Type 2 Diabetes Mellitus (T2DM) patients at different stages of Urinary Albumin-to-Creatinine Ratio (UACR) and varying degrees of urinary transferrin. Furthermore, to analyze the correlation between serum MLT and inflammatory (Tumor Necrosis Factor-alpha, TNF-α), fibrotic (Transforming Growth Factor beta, TGF-β) and Ferroptosis Proteins (Ferritin Heavy Chain, FTH; Glutathione Peroxidase 4, GPX4; Malondialdehyde, MDA).

Methods: Divided participants into three groups based on their UACR. Additionally, the participants were stratified based on their urinary transferrin levels. The levels of serum MLT and 5-HT, as well as TNF-α, TGF-β, and FTH, GPX4, MDA were measured and statistically analyzed.

Results: Serum MLT, GPX4 and FTH levels decreased with an increase in UACR (P < 0.001). Ridge regression analysis indicated significant associations between MLT and MDA, TGF-β, TNF-α, FTH, GPX4, UACR and TRU (P < 0.01). Receiver Operating Characteristic (ROC) analysis demonstrated that MLT had a sensitivity of 0.873 for the diagnosis of Diabetic Kidney Disease (DKD).

Conclusion: In patients with T2DM, serum MLT is associated with UACR levels and inflammatory, fibrotic, and ferroptosis markers. This study suggests that these correlations could have potential implications in the pathophysiology and diagnosis of DKD.

The pollution distribution characteristics of 33 selected steroid hormones were investigated in Baisha River, a river entering the sea in Beibu Gulf. The detection rate of steroid hormones at 8 sites ranged from ND to 100%. The concentration ranges of estrogen, androgen, glucocorticoid, and progesterone were from ND to 2.4 ng/L (estriol), from ND to 16.05 ng/L (androsterone), from ND to 1.9 ng/L (hydrocortisone), and from ND to 1.85 ng/L (norgestrel), respectively. There were significant seasonal variations in steroid hormone concentration, with the frequency and concentration of steroid hormone were higher in dry season than in wet season. The concentration of steroid hormones in Baisha River increased from the upper reaches to the middle reaches or lower reaches and then decreased to the estuary. Compared with steroid hormones in other rivers at home and abroad, the concentration of steroid hormones in the Baisha River water body is at a medium-low level. The results of the endocrine disrupting effect analysis showed that the total estrogen toxic equivalent (EEQs) and androgen toxic equivalent (TEQs) values were greater than 1 ng/L, indicating certain estrogen/androgen activity. The rest did not produce significant estrogenic/androgenic effects. The results of the ecological risk evaluation showed that methyltestosterone (17-MT) and estrone (E1) were at high risk at some sits in the basin, while other steroid hormones were at low or no risk. This study contributes to the understanding of steroid hormone contamination in the water body of Baisar River in low urbanised and rural areas, and provides reference value for the study of steroid hormones in the Gulf river.