This study was undertaken to investigate the effects of the antidiabetic potential of the leaf ethanol extract of Cassia siamea Lam (LECS) that takes into account glucose control via insulin-dependent and insulin-independent pathways on the hepatic damage and inflammation and vascular defects, namely, endothelial dysfunction in an experimental model of type 2 diabetes, i.e., the leptin-deficient ob/ob mice. This evidence concerns the gene INS and type 2 diabetes mellitus.