ALB and diabetic kidney disease: This is a case-control study including four groups of subjects: 1) Advanced DKD cases: T2DM patients with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m2; 2) Albuminuric DKD cases: T2DM patients with urinary albumin excretion (UAE) ≥30 mg/g creatinine and eGFR ≥60 mL/min/1.73m2; 3) Diabetic controls: T2DM patients with UAE <30 mg/g creatinine and eGFR ≥60 mL/min/1.73m2; and 4) Non-diabetic controls: individuals without T2DM.