Impact of physiological fluctuations of sex hormones during the menstrual cycle on glucose metabolism and the gut microbiota.

Diabetes mellitus is one of the most prevalent chronic diseases in the world. Previous studies have shown differences in glucose metabolism between males and females. Moreover, difficulties in medication adherence have been reported in females with type 2 diabetes. These observations are believed to be caused by fluctuations in sex hormone concentrations during the menstrual cycle. Furthermore, gut microbiota is linked to female host metabolism and sex hormone production. Understanding the interactions between fluctuating hormone concentrations during the menstrual cycle, gut microbiota as well as glucose metabolism in humans is of great relevance because of the increasing prevalence of diabetes and the consequent need to expand preventive efforts. To determine and summarize the existing evidence, deduce future research needs to maintain female health, and investigate the relationship between the physiological menstrual cycle and glucose metabolism, a literature search was performed. Surprisingly, the relationship between variations in the course of the menstrual cycle and glucose metabolism has been examined in healthy female subjects using an OGTT or IVGTT already in studies from 1967 to 2020; however, the overall number of studies is rather small. The results are contradictory, as some studies have detected differences in glucose concentrations depending on the different cycle phases, whereas others have not. Moreover, some studies have shown lower glucose levels in the follicular phase than in the luteal phase, whereas another study detected lower glucose levels in the luteal phase. Data on gut microbiota in relation to the menstrual cycle are limited. Conflicting results exist when examining the effect of hormonal contraceptives on the gut microbiota and changes in the course of the menstrual cycle. However, the results indicate that the menstrual cycle, especially fluctuating sex hormones, might have an impact on the composition of the gut microbiota. In conclusion, the menstrual cycle may affect the composition of the gut microbiota as well as glucose metabolism. These results indicate that glucose tolerance may be the greatest in the follicular phase; however, further well-conducted studies are needed to support this assumption.

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PMID: 38382644