Explore how menstrual hormones influence reproductive and metabolic health, including their impact on blood sugar levels and insulin sensitivity.

Keywords: menstrual cycle, hormones, insulin sensitivity, blood sugar, metabolic health, CGM, reproductive health, PCOS, fertility

Key takeaways

The menstrual cycle is controlled by four key hormones: follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and progesterone. These hormones regulate the cycle's four phases: follicular, ovulation, luteal, and menstruation. Here’s how they work:

• Follicular Phase: FSH promotes follicle growth; estrogen thickens the uterine lining.
• Ovulation: LH surges, releasing an egg.
• Luteal Phase: Progesterone supports the uterine lining.
• Menstruation: Progesterone and estrogen drop, leading to the uterine lining shedding.

Hormones also affect metabolic health. Estrogen improves insulin sensitivity, while progesterone increases insulin resistance, impacting blood sugar levels. Tools like CGMs (Continuous Glucose Monitors) help track these hormonal effects, offering insights for managing conditions like PCOS and diabetes.

Understanding these patterns helps tailor health strategies, from blood sugar management to fertility tracking.

Understanding Glucose Dynamics: Insulin Sensitivity throughout the Menstrual Cycle

Hormones in the Menstrual Cycle

The menstrual cycle is driven by four key hormones that work together to regulate reproductive health. These hormones also play a role in metabolic health and fertility.

Follicle-stimulating hormone (FSH)

Produced by the pituitary gland, FSH starts the cycle by promoting follicle growth and encouraging estrogen production. It also triggers the release of inhibin, which helps control FSH levels, ensuring only one follicle becomes dominant. Estrogen production influenced by FSH has additional effects on metabolic health.

Luteinizing hormone (LH)

LH complements FSH but has its own critical functions. Its primary role is to trigger ovulation through a sudden surge. After the egg is released, LH helps form the corpus luteum from the ruptured follicle, which then produces hormones that affect metabolic processes.

Estrogen and progesterone

These hormones work together to prepare the body for a possible pregnancy. Estrogen levels rise during the follicular phase, thickening the uterine lining and improving insulin sensitivity. Progesterone, which dominates the luteal phase, has been linked to less stable blood sugar levels, as shown in CGM studies.

If pregnancy doesn’t occur, both estrogen and progesterone levels drop, leading to menstruation. This cycle repeats roughly every 28 days, though variations are normal.

Understanding how these hormones interact provides insight into their broader effects on metabolic health and blood sugar regulation.

Hormones and Metabolic Health

The connection between menstrual hormones and metabolic health plays a key role in regulating blood sugar throughout the cycle. Studies show clear patterns in how hormonal shifts influence glucose levels and insulin sensitivity.

Cycle and Blood Sugar Changes

Blood sugar levels tend to follow predictable patterns during the menstrual cycle due to hormonal shifts. In the follicular phase, when estrogen is more dominant, women often experience better insulin sensitivity and steadier blood sugar levels. Estrogen helps insulin work more effectively, while progesterone, which rises in the luteal phase, can lead to insulin resistance. This creates natural variations in glucose metabolism.

A notable metric, Time in Range (TIR) - the percentage of time blood sugar stays within a healthy range - drops during the mid-luteal and late luteal phases. TIR values can decline from 61% to as low as 55% according to this study. This highlights how hormonal changes influence metabolic control across different phases of the cycle.

Using Continuous Glucose Monitoring (CGM)

Continuous glucose monitors (CGMs) offer real-time data, helping women track how hormones affect their blood sugar and make informed adjustments.

"This preliminary analysis may pave the way for a more in-depth examination of the relationship between menstrual cycle phases and glucose levels, offering potential implications for diabetes management." - Shruthi Mahalingaiah, Assistant Professor at Harvard T.H. Chan School of Public Health

Platforms like Vively integrate CGM technology with personalised coaching to help users manage hormone-driven blood sugar shifts more effectively.

Here’s a quick look at how different phases of the menstrual cycle impact blood sugar and insulin sensitivity:

These insights allow women to tailor their lifestyle choices and medical strategies to align with their hormonal rhythms. For those managing conditions like PCOS or diabetes, this information is especially useful for creating individualised approaches to care.

Applying Hormone Knowledge

Understanding how hormones work can help manage reproductive and metabolic health more effectively. Tools like continuous glucose monitors (CGMs) make it easier to track and use this information in daily life.

Tracking Cycles and Fertility

Ovulation predictor kits (OPKs) are highly reliable, with up to 99% accuracy in identifying fertile windows(Vanderhoff et al. 2024). Pairing cycle tracking with CGMs adds another layer of insight by connecting hormonal phases to blood sugar levels. For example, programs like Vively’s CGM system link cycle stages to glucose trends, providing practical guidance.

Each phase of the menstrual cycle requires a different focus:

• Follicular phase: Prioritise blood sugar stability.
• Ovulatory phase: Highlight fertility windows.
• Luteal phase: Pay attention to changes in insulin sensitivity.

Managing Hormone Imbalances

Addressing hormone imbalances begins with recognising key signs, such as:

• Irregular periods
• High androgen levels
• Insulin resistance
• Shifts in blood sugar patterns

For women going through menopause, hormone tracking becomes even more critical. Research indicates that lower estrogen levels can greatly affect insulin sensitivity. Using CGM tools during this time helps women make informed lifestyle adjustments to support their metabolic health.

Tracking hormones allows for tailored health strategies. Studies reveal that women who monitor both their cycles and glucose levels can better maintain their Time in Range (TIR) by adapting their diet and exercise to their hormonal phase. The research is currently focussed on people with type 1 diabetes.

Conclusion

Hormones and Their Impact

Hormones play a key role in the menstrual cycle, influencing both reproductive and metabolic health. For example, estrogen improves insulin sensitivity, while progesterone tends to reduce it, which can affect blood sugar control. Studies indicate that people maintain healthy glucose levels about 68.5% of the time during the follicular phase, compared to 66.8% during the luteal phase. These findings are particularly relevant for managing conditions like PCOS, menopause, and other metabolic health concerns.

Tools for Managing Hormonal Health

Advancements in technology now make it easier to monitor and respond to hormonal changes. Platforms like Vively use continuous glucose monitoring (CGM) paired with personalised coaching to help users track how their glucose levels shift throughout the menstrual cycle. This approach empowers individuals to make smarter decisions about their diet, exercise, and overall lifestyle.