Associations of urinary, glomerular, and tubular markers with the development of diabetic kidney disease in type 2 diabetes patients.

Objective: To evaluate the associations of urinary markers (eg albumin), glomerular (eg transferrin [TRF], immunoglobulin G [IgG]), and tubular (eg α1-microglobulin [α1-MG], β2-microglobulin [β2-MG]) markers with the development of diabetic kidney disease (DKD) in type 2 diabetes patients, as assessed by estimated glomerular filtration rate (eGFR) and albuminuria.

Methods: A total of 252 type 2 diabetes patients and 50 nondiabetic controls from Tianjin, China, were selected. Diabetic patients were divided into three groups according to eGFR levels, including groups A, B, and C with eGFR ≥90 (n=94), 60-89 (n=94), and 30-59 (n=64) mL/min/1.73 m2 . Urine levels of glomerular and tubular markers were detected in first morning urine samples, and their associations with eGFR and albuminuria analyzed.

Results: Urinary levels of IgG, TRF, and β2-MG were significantly elevated in diabetic patients with normal eGFR compared with nondiabetic control subjects. Urinary levels of all markers increased per eGFR stratum. All kidney damage markers were significantly associated with eGFR in univariate analysis (standard β between -0.35 and -0.28; all P<.001). After adjusting for known confounders, only the tubular markers α1-MG (standard β=-0.25; P=.013) and β2-MG (standard β=-0.18; P=.039) retained significant associations with eGFR. All kidney damage markers were significantly associated with albuminuria, independent of age, duration of diabetes, and eGFR (standard β between 0.45 and 0.86; all P<.001).

Conclusions: Only the tubular markers α1 -MG and β2 -MG were associated with eGFR independent of albuminuria, suggesting that they may play an important role in the development of DKD.