AIM:To investigate whether the expression of perilipin 2(PLIN2)in renal tubular cells could predict a decline in renal function in diabetic kidney disease(DKD)patients,and to explore the potential mechanisms in-volved in renal tubular cell injury induced by PLIN2 during the progression of DKD.METHODS:Control individuals(n=12)and DKD patients(n=51)were enrolled in this retrospective cohort study.Demographic and laboratory data were col-lected.A simplified linear mixed-effects model was applied to assess the estimated glomerular filtration rate(eGFR)slope.The relationship between PLIN2 and renal function decline in DKD patients was predicted by Spearman correlation analysis and a generalized linear model.BKS-db/db diabetic mice and streptozotocin-induced diabetic mice were used.Primary renal tubular cells were treated with glucose and transfected with small interfering RNA or plasmid.Western blot-ting and immunofluorescence staining were used to detect PLIN2 expression.Lipid droplets were stained with oil red O.The oxygen consumption rate(OCR)of mitochondria was measured using an extracellular flux analyser.RESULTS:The expression of PLIN2 was markedly higher in the tubules of DKD patients than in those of control subjects.After 24(12,39)months of follow-up,the eGFR slope of DKD patients was-7.42(-19.77,-2.09)mL/(min·1.73 m2·year).An in-crease in the baseline percentage of PLIN2-positive tubules was significantly associated with the eGFR slope during the fol-low-up period[hazard ratio(HR)=1.90,95%confidence interval(CI):1.00～3.58],indicating that tubular PLIN2 could predict a decrease in renal function in DKD patients.Both the accumulation of lipid droplets and the expression of PLIN2 were markedly greater in the tubules of diabetic mice than in those of control mice.Glucose treatment induced lipid droplet accumulation and PLIN2 expression in renal tubular cells.Knockdown of PLIN2 significantly alleviated glucose-in-duced lipid droplet accumulation,whereas PLIN2 overexpression aggravated glucose-induced lipid droplet accumulation.The decrease in mitochondrial OCR in renal tubular cells induced by glucose treatment was alleviated after PLIN2 knock-down.However,overexpression of PLIN2 directly decreased the mitochondrial OCR.CONCLUSION:The PLIN2 ex-pression in tubules predicts a decline in renal function in patients with DKD.The PLIN2 suppresses mitochondrial aerobic respiration and contributes to the accumulation of lipid droplets in renal tubular cells to promote the progression of DKD.