D-Chiro-inositol (DCI) exerts a hypoglycaemic effect, participates in lipid metabolism and reduces kidney damage. In this study, we preliminarily explored the protective effect of DCI on renal injury in diabetic mice. Male db/db mice were used in this study. After treatment with DCI (35 and 70 mg/kg/d) for 6 consecutive weeks, random blood glucose (RBG) measurements were conducted at 0 and 6 weeks. Creatinine (Cr) and serum blood urea nitrogen (BUN) levels were measured using assay kit, and morphological changes in the kidneys were observed by HE staining, Masson staining and electron microscopy. Immunohistochemical and Western blot experiments were used to examine the protein expression of matrix metalloproteinase-9 (MMP-9), nuclear factor-κB (NF-κB) and peroxisome proliferator-activated receptor-γ (PPAR-γ). We discovered that the increased RBG levels were alleviated after treatment with DCI. Moreover, the Cr and BUN levels were reduced, glomerular mesangial hyperplasia was alleviated, and the degree of renal fibrosis was reduced. In addition, DCI improved the protein expression of MMP-9 and PPAR-γ in kidney tissue, which in turn inhibited NF-κB protein expression, as shown by immunohistochemistry and Western blotting. Our findings showed that DCI ameliorated the renal injury induced by diabetes by upregulating MMP-9 and PPAR-γ expression and downregulating NF-κB expression. We preliminarily concluded that the renal protective effect of DCI on diabetic mice may occurs through the MMP-9/NF-κB signalling pathway.