Abstract: To investigate the potential hypoglycemic effect of nanosuspensions of honokiol and explore the underlying mechanisms, a high fat diet (HFD) was studied in C57BL/6J mice divided into five groups:normal diet (ND), HFD, HFD/honokiol-sodium carboxymethyl cellulose (CMC-Na) (Hono-CMC, 100 mg·kg^-1), HFD/honokiol-Nano (Hono-Nano, 80 mg·kg^-1), HFD/metformin (HFD/Met, 200 mg·kg^-1). Fasting blood glucose (FBG) and body weights (BW) of mice were measured every seven days. After 30-day treatment, an oral glucose tolerance test (OGTT) was performed, and blood and tissue samples were collected for analysis. All animal experiments were approved by the Research Animal Care Committee of Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine. The data showed Hono-Nano and metformin reduced FBG, BW, and markedly improved OGTT of mice compared to HFD group (P<0.05). Hono-CMC produced nonsignificant impact on FBG, BW of mice, while OGTT of mice was improved by Hono-CMC (P<0.05). Meanwhile, none of these treated groups showed significant effects on regulating serum insulin levels, but all of them exhibited decreased serum glucagon levels notably compared to the HFD group (P<0.05). Western blot analysis revealed that honokiol up-regulated levels of p-AMPK and p-FOXO1 in liver tissue of HFD mice (P<0.05), which resulted in activation of AMPK and inhibition of FOXO1. Moreover, the expression of PEPCK (a key enzyme of gluconeogenesis) was decreased by honokiol (P<0.05). Taken together, our findings demonstrate that nanosuspension of honokiol is more effective than CMC-Na-suspension of honokiol on blood glucose controlling in HFD mice. The hypoglycemic effects of honokiol might rely on suppressing hepatic gluconeogenesis via activating AMPK and inhibiting FOXO1.