Superfuel on a Schedule: the effects of glucose during the menstrual cycle

How do hormonal fluctuations during the menstrual cycle effect glucose levels and why is this even important. Hello, my name is Maria Farkas Freitas, and to test that question, I designed a controlled experiment. For the length of the menstrual cycle a participant wore a continuous glucose monitor. Every morning they ate the same breakfast then recorded their glucose levels every five minutes. The results were very interesting. It was found that during the menstrual and luteal phases glucose levels were higher than average due to stress, pain, and other hormonal changes like the rise in progesterone during the luteal phase. In the follicular and ovulation phase, glucose levels were very low. This is because of a rise in estrogen which creates insulin sensitivity, letting your cells use insulin more efficiently. This research is important because it can help women better understand their bodies and how their eating habits effect their overall health.

Thank you for listening.

Purpose and inspiration

The purpose of this experiment is to explore how different hormonal fluctuations during the menstrual cycle affect glucose levels. This experiment was conducted to expand knowledge on women's health, which is an incredibly under researched topic in health sciences.

This project was inspired by limited public knowledge in women's health. Studies have been historically representative of male populations with limited female participants (only 40% of participants in clinical trials are women). Metabolic health disorders have also been rising (one in five adults have a metabolic health disorder). Our food lacks nutrients and is high in sugar, leading to many disorders like diabetes. Women, having many hormonal changes every month affecting their glucose levels, are prone to these conditions (27.5% of women are overweight), particularly women in pregnancy (3-8% of pregnant women are diagnosed with diabetes) or entering menopause (32-60% of menopausal women have metabolic health disorders)

Historically, women preferred to be slim over being muscular. This significantly impacts women's health as high muscle mass can help the body regulate glucose better. These issues have yet to be faced head on by preventative medicine. The cycle needs to be broken, and this experiment brings awareness and understanding to women's metabolic health.

Benefits to our world

Everyone can benefit from this research to better understand women's health. We can also gain knowledge of metabolic health to prevent illnesses. For women, this research helps them better understand their bodies and how their eating habits affect their overall health.

The original intent was to conduct the experiment with multiple participants, including five menstruating females, 5 perimenopausal females, and one pre menstruating female. Unfortunately, the experiment was limited due to access to continuous glucose monitors and financial restrictions.

To conduct the experiment, a continuous glucose monitor was worn during the length of the participant's menstrual cycle. The participant ate the same breakfast daily recording their glucose levels every five minutes for ninety minutes. This experiment was able to observe how different hormonal fluctuations during the menstrual cycle affected morning glucose levels.

In the experiment, the controlled variables included the type and amount of food consumed, the time and frequency which the data was recorded, the equipment used, and the participant. These variables were controlled carefully, measuring each consumable with the same equipment, so it stayed as consistent as possible. The continuous glucose monitors used were the same throughout the experiment and that the brand was known to have consistent results.

The continuous glucose monitor collected data using a tiny sensor inserted under the participant’s skin that measures glucose levels in the interstitial fluid (fluid between the cells that comes from substances leaking from your blood capillaries) which the glucose enters after flowing through the blood stream. The continuous glucose monitor tracks these glucose results in real time. To ensure the most consistent results, the monitor was scanned in case there was any disruption from the automatic scan.

Findings

During the menstrual phase, glucose levels were slightly higher than normal (3.9-5.5 mmol). This is likely due to stress, pain, and small hormonal changes. Stress and pain trigger a fight or flight response in the body. Hormones (chemical messages that regulate the body) like adrenaline prompt the liver to release stored energy (glucose) into the blood stream. This creates a spike in glucose levels. These variables outweighed the natural insulin sensitivity coming from a rise in estrogen in this phase, which typically makes the body use insulin more efficiently, lowering glucose levels.

During the follicular phase, results were unexpected. Glucose levels were dropping much lower (4.4 on average) compared to the other phases. This is because of a significant increase in estrogen levels. Estrogen raises insulin sensitivity, making the body's cells use insulin more efficiently. When the body can use less insulin to stabilise glucose levels, it doesn't have to package as much insulin into tissues. This also means the body will not gain fat. High estrogen levels have also been linked to a decrease in the likelihood of Alzheimer's, overall making for better metabolic and brain health.

During ovulation results were interesting, glucose levels were low (3.8) then they spiked slightly (5.6) and dropped down again (2.9). This effect happens because of rising estrogen right before this phase, which gives the body an LH (luteinizing hormone) surge, so the dominant follicle will rupture and release a mature egg for fertilisation. LH can also increase insulin resistance, but in this instance the result for this was outweighed by low glucose levels from estrogen.

During the luteal phase results varied widely. In the beginning of the luteal phase, glucose levels were low (4.9) , then leading into the mid luteal phase they began to rise (5.7), which was expected. At the start of the luteal phase, glucose levels were low because the body was coming down from a spike in estrogen after ovulation. Then in the mid luteal phase, progesterone rose creating insulin resistance, which is when the cells cannot use insulin as efficiently, leading to higher glucose levels. Insulin resistance is also linked to glucose metabolism, which is the process of turning carbohydrates into glucose, and glucose into ATP (energy). This happens as the body is preparing for a potential pregnancy and needs more energy (higher glucose levels) to function. High progesterone also leads the body to have more cravings (especially carbohydrates) as it makes the body feel as though it needs more energy.

In the experiment, glucose levels would already be increased in the morning despite the participant being in a fasting state. This is because of the dawn factor. The dawn factor or dawn phenomenon is the early morning rise in glucose between four and eight am in the morning, giving the body a boost of energy to prepare to wake up.

In conclusion, my hypothesis was only partially supported. Different hormonal fluctuations during the menstrual cycle do affect glucose levels. However, results can vary between individuals due to different genetics and health conditions.

During the follicular and ovulation phases, glucose levels were consistently low, sometimes even out of normal range (3.9-5.5mmol).

During the menstrual and luteal phases glucose levels were higher than average. Stress and pain can increase glucose levels and are very prevalent in the menstrual phase. In the luteal phase, glucose levels are higher due to a rise in progesterone.

Overall, I found that hormones like progesterone and estrogen have a measurable effect on glucose levels. Estrogen tends to lower glucose levels while progesterone causes it to increase. It was also found that LH (luteinizing hormone) can slightly raise glucose levels.

The dawn factor played a crucial role in the results of this experiment. It was found that glucose levels would spike before the participant was able to digest any food and before they even consumed food, which is consistent in scientific literature.

The results demonstrated that hormonal changes in the menstrual cycle affect the human body in significantly profound and varied ways. This makes it important for women to pay attention to their menstrual cycles and diet as hormone levels have an impact on glucose, metabolism, and overall health. This research can also contribute to lowering rates in female metabolic health disorders, as it shows women safe times to consume carbohydrates.

Next steps

In the future I would like to develop my understanding of the menstrual cycle to discover if there's something even deeper happening inside the female body. I would also like to expand my knowledge of metabolic health and further discover the internal relationships between glucose, insulin, and the effect on the body. Future improvements include having more participants, ensuring greater relevance to the general population from my results, participants of different ages (such as women entering menopause) or compare glucose responses between genders. Future research could also include testing body temperature and sleep patterns.

Thank you to my teachers and parents who helped inspire me to dig deeper into what I'm passionate about.

Thank you to Dr. Chantel Braun and Dr. Shan Weeratunga for donating the continuous glucose monitors used for this experiment.

Finally, thank you mom for supporting me through this experiment and pushing me to expand my knowledge on the human body.

I truly am thankful and couldn’t have done this without all your help.

Web pages

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Labots, G., Jones, A., de Visser, S. J., Rissmann, R., & Burggraaf, J. (2018). Gender differences in clinical registration trials: is there a real problem? British Journal of Clinical Pharmacology, 84(4), 700–707. https://doi.org/10.1111/bcp.13497

Mayo Clinic. (2025). Type 2 diabetes. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/type-2-diabetes/symptoms-causes/syc-20351193

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Images

Shyam Bishen, & World Economic Forum. (2023, October 11). The gender bias in healthcare costs - and other health stories. World Economic Forum. https://www.weforum.org/stories/2023/10/gender-bias-healthcare-costs-health-news/

Al Hayek, A. A., Robert, A. A., & Al Dawish, M. A. (2020). Acceptability of the FreeStyle Libre Flash Glucose Monitoring System: The Experience of Young Patients With Type 1 Diabetes. Clinical Medicine Insights: Endocrinology and Diabetes, 13, 117955142091012. https://doi.org/10.1177/1179551420910122

53 Reactions | Did You Know That Hormonal Changes during Your Menstrual Cycle Can Make Blood Glucose Levels Unpredictable? From Cravings to Mood Swings, These Fluctuations Can Impact Diabetes Management. Track Your Cycle and Blood Sugar Patterns to Stay Prepared. Together with Your Healthcare Provider, You Can Take Control and Thrive Every Step of the Way! #Diabetes #DiabetesCare #DiabetesTip #RocheDiabetesCareME | Roche Diabetes Care ME, 2026

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