The invention discloses an application of clostridium butyrate in a preparation for prevention and treatment or adjuvant therapy of hyperglycemia and belongs to the technical field of prevention and treatment of diabetes. According to the application, during the prevention and treatment or adjuvant therapy of the hyperglycemia, butyric acid is produced in an intestinal tract, meanwhile, florae of the intestinal tract are changed, signals are sent to an ileum, a liver, a pancreatic gland and a brain by a portal vein blood sugar sensor, the ileum is promoted to secrete (GLP-1) glucagon-like peptide-1, the gluconeogenesis of the liver is lowered, pancreatic beta cells are protected, the secretion of insulin of the pancreatic gland is promoted, and thus, the action of reducing blood sugar is exerted. The clostridium butyrate is a medicine which has been proven by clinical drug trials and can be directly taken orally.