HLA-G and diabetic kidney disease: Previous studies have found that serum levels of cystatin C (CysC), β2-microglobulin (β2-MG), and homocysteine (Hcy) are significantly more sensitive than serum creatinine (SCr) and blood urea nitrogen (BUN) for detecting early-stage DKD, providing a more accurate reflection of glomerular filtration function and the extent of renal damage in patients (7, 8).