Moringa concanensis Nimmo is a medicinal plant for treating various human illnesses including menstrual pain, high blood pressure, jaundice, inflammation, pain, fever, sore eyes, and cholesterol in Indian folk medicine. Despite its versatility, its antihyperglycemic mechanism of action (in vitro and in vivo) remains unclear. Therefore, in this study we developed the possible antihyperglycemic mechanism of action in 3T3-L1 cells by evaluating mRNA and protein expression, which are associated with adipogenesis and lipogenesis (insulin sensitizer). Also, the antihyperglycemic activity of the ethanolic extract of M. concanensis Nimmo leaves (EEMCN) was evaluated on glucose, insulin, biochemical, and lipid profile in experimental diabetic rat models induced with streptozotocin (STZ). Results showed that EEMCN leaves enhanced lipid accumulation in 3T3-L1 cells, as assessed by Oil Red O staining, and upregulated gene expression level of PPAR-γ, C/EBP-α, t-SREBP, FAS, Glut-4, adipogenin, DAG, and LPL through Akt signaling in 3T3-L1 cells. Also, EEMCN treatment increased body weight and insulin level and lowered blood glucose, HbA1c, amylase, and lipid profile level in STZ-induced diabetic rats. In conclusion, EEMCN possesses in vivo antidiabetic potential, having such efficacy through a mechanism of action that involves antihyperglycemic, hypoglycemic, and potential insulin sensitizer (PPAR-γ, C/EBP-α/Akt over expression) action.