Abstract: AIM: To investigate the circadian rhythm of blood sugar level in healthy as well as diabetic rats and tofind the appropriate timefor using glopizide in diabetic rats.METHODS: The blood sugar level of two kinds of rats was detected at 6 ∶00, 12 ∶00, 18 ∶00, 0 ∶00 and circadian rhythm of the data was analyzed.Different groups of diabetic rats were treated with glopizide at 9 ∶ 00 or 21 ∶00 respectively.The variation of blood sugar level andits average were compared between groups after the treatment.RESULTS: Significant circadian rhythm of the blood sugar level was foundin healthy rats, but not in diabetes rats.The variation of blood sugar level andits average were lower when glopizide was given at 9 ∶00 than those at 21 ∶00.CONCLUSION: There is a circa-dian rhythm of blood sugar level in healthy rats and glop-izide shows a better action of decreasing blood sugar in the morning than evening.

Key words: chronobiology, diabetes, chronothera-peutics, rats, glopizide