Background: Treatment for diabetes is traditionally performed using subcutaneous insulin injection and oral anti-diabetic agents, especially plant-derived hypoglycemic agents. Besides, bioresonance therapy or biophysical information therapy is also performed for diabetes and other disorders as a form of complementary medical method. This study aimed to explore a specific hypoglycemic frequency of human insulin in microwave band and to assess the effects of irradiation of microwave at the frequency on blood glucose (BG) levels in normal and diabetic rats.Methods: One hundred and ninety-five normal and 25 diabetic Wistar rats were used in this experiment.Among peak frequencies obtained from frequency-intensity curve of human insulin solution by using Network Analyzer, a hypoglycemic frequency was identified by measurements of BG levels after irradiation of microwave in 18 h fasted normal rats. BG and serum insulin levels in normal and diabetic rats, and α-Dglucose concentration were determined after irradiation of microwave at the frequency.Results: Among six peak frequencies obtained from frequency-intensity curve of insulin solution, only 15.37 GHz could exert the ability to decrease fasting blood glucose (FBG) level and glucose tolerance in normal rats, especially, 15.370 GHz showed the highest effect. Whole-body irradiation of microwave at the frequency with intensities of 0.1 to 10 mW/cm 2 for 1 hour lowered FBG and BG levels after glucose loading in normal and diabetic rats, and showed no changes in fasting serum insulin levels in normal and diabetic rats.Conclusions: Irradiation of 15.370 GHz microwave lowers BG level in normal and diabetic rats just like insulin.