“…Up to now, previous studies have recommended some early diagnosis or risk prediction models for DKD based on clinical serum/urine biomarkers of renal function, transcriptomics markers and/or metabonomics markers (11)(12)(13)(14)(15). Several clinical risk factors associated with the occurrence and progression of DKD have been reported, including age, gender, hypertension, dyslipidemia, glycated hemoglobin (HbA1c), the drug use of angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB), diabetes duration, body mass index (BMI), and smoking, among others (7,11,13,16). Additionally, there have been many studies on urinary biomarkers of renal injury commonly used in clinical practice, such as urinary albumin-to-creatinine ratio (ACR), estimated glomerular filtration rate (eGFR), alpha-1microglobulin to creatinine ratio (A1MCR), neutrophil gelatinaseassociated lipocalin to creatinine ratio (NGAL/Cr), transferrin to creatinine ratio (UTRF/Cr), retinol-binding protein to creatinine ratio (URBP/Cr), and orosomucoid to creatinine ratio (UORM/Cr), among others (7,(13)(14)(15)(16)(17).Recently, one of our previous crosssectional studies has reported that the serum fasting C-peptide is an independent risk factor for the odds of renal dysfunction in patients with type 2 diabetes, furthermore, the association between them is not linear, but non-linear (6).…”