BACKGROUND CASC15 has been recently characterized as an oncogenic lncRNA. This study aimed to investigate the role of CASC15 in diabetic patients complicated with chronic renal failure (DCRF). MATERIAL AND METHODS Levels of CASC15 in plasma derived from 3 groups of participants were measured by qPCR and compared by ANOVA and Tukey test. The interaction between CASC15 and miR-34c was analyzed by performing cell transfections. Cell apoptosis assay was performed to analyze the effects of transfections on the apoptosis of CIHP-1 cells (podocytes). RESULTS We found that CASC15 in plasma was upregulated in DCRF compared with diabetic patients (no obvious complications) and healthy controls. Upregulation of CASC15 distinguished DCRF patients from healthy controls and diabetic patients. High D-glucose environment induced the upregulation of CASC15 in cells of the human podocyte cell line CIHP-1. Overexpression of CASC15 did not affect miR-34c in CIHP-1 cells, but bioinformatics analysis showed that CASC15 can sponge miR-34c. Overexpression of CASC15 led to an increased apoptotic rate of CIHP-1 cells, and miR-34c overexpression led to a decreased apoptotic rate of CIHP-1 cells. In addition, CASC15 overexpression attenuated the effects of miR-34c overexpression on cell apoptosis. CONCLUSIONS Therefore, CASC15 is upregulated in DCRF patients and promotes the apoptosis of podocytes by sponging miR-34c. Our study adds to our understanding of the pathogenesis of DCRF and suggests that CASC15 could serve as a potential therapeutic target of DCRF.