NDUFS4 and diabetic kidney disease: Importantly, NDUFS4 staining was significantly decreased in the kidney glomeruli of diabetic subjects with normoalbuminuria as compared to that of healthy donors (5.8 ± 0.7 vs. 14.0 ± 1.9 pixel/μm2, P<0.001; Fig. 1k), suggesting that NDUFS4 downregulation may have occurred prior to the clinical manifestation of DKD.