Therapeutic Effect of Metformin on Glucose and Insulin Metabolism in Streptozotocin-Induced Diabetic Rats under Circadian Rhythm Disruption and Normal Conditions

Abstract

Introduction: The circadian rhythm, a regulator of sleep-wake cycles, can lead to metabolic disorders and decreased blood insulin levels when disrupted, thereby increasing the risk of diabetes. This study evaluated the effects of metformin on insulin and glucose levels in rats with streptozotocin (STZ)-induced diabetes under circadian rhythm disruption.

Methods: In this study, 36 adult male Wistar rats were divided into two groups: one group was maintained under normal light conditions (12 hours of light/12 hours of dark), while the other group was exposed to continuous light (resulting in circadian rhythm disruption). Diabetes was induced with a single intraperitoneal injection of STZ, and confirmation of diabetes was performed 3 days later using a glucose test. The treatment group received 500 mg/kg of metformin daily for two weeks. At the end of the study, blood samples were collected, and glucose and insulin levels were measured using the ELISA method.

Results: This study demonstrated that circadian rhythm disruption caused by constant light exposure negatively impacts glucose metabolism, leading to increased blood glucose levels and decreased insulin levels. In streptozotocin-induced diabetic rats, two weeks of metformin treatment significantly reduced blood glucose levels, although no significant increase in insulin levels was observed.

Conclusion: Circadian rhythm disruption, characterized by reduced insulin secretion and sensitivity, as well as impaired glucose homeostasis, increases the risk of progression to type 2 diabetes. These results underscore the importance of considering circadian rhythms when determining the timing of medication administration and developing diabetes treatment plans, which could enhance diabetes management.