This study investigated the effects of a nopal (Opuntia ficus-indica) complex (OF) on blood glucose metabolism in db/db mice for 4 weeks. Food and water intake significantly decreased in OF-treated mice compared to controls (p<0.05). In addition, blood glucose and plasma insulin levels were significantly reduced in the OF-treated group compared to the controls (p<0.05). Histopathological analysis showed that the morphology of pancreatic islets was improved in the OF-treated db/db mice. Immunohistochemistry of the pancreatic islets showed that insulin production and the number of ${eta}$-cells apparently increased.