One of the lesser-known effects of the menstrual cycle is its impact on blood sugar levels. A study published in Nature in August of 2023 found that fluctuations in hormone levels during the menstrual cycle can also impact blood sugar levels, potentially leading to complications for women with diabetes or any blood sugar regulation issues. These changes can affect her overall health and well-being and lead to a range of symptoms and health concerns.

Exploring the link between the menstrual cycle and blood sugar may benefit women of all ages—from puberty to post-menopause—and also emphasize the importance of self-care during this time. By understanding this intricate connection, women can take better control of their health, manage their blood sugar, and support their overall metabolic wellness.

Study Takeaways

To collect data for the study, the 49 participants wore continuous glucose meters (CGMs) to measure their menstrual hormones daily and self-reported the characteristics of their cycles to determine their phase. Higher levels of glucose were seen in the luteal phase (after ovulation) and lower levels in the late follicular phase (just prior to ovulation). Blood sugar tended to drop significantly with the onset of menstruation.

The study also found several other correlations between hormones and blood sugar, including, “negative associations between each of daily estrogen level, step count, and low degrees of fatigue with higher median glucose levels.” The study suggests fatigue experienced during the menstrual cycle could be related to blood sugar levels.

The research concluded that insulin sensitivity—or how well the body responds to insulin—is higher in the follicular phase and lower in the luteal phase. A 2015 study published in the Journal of Diabetes Science and Technology on participants with Type 1 diabetes determined there is a decrease in insulin sensitivity nearing ovulation that peaks in the luteal phase.

An earlier study published in 2010 in The Journal of Clinical Endocrinology & Metabolism found that estrogen and progesterone levels were positively associated with insulin resistance, a condition where the body’s cells become less responsive to insulin, leading to higher blood sugar levels.

Overall, the CGM study supports that hormones affect blood sugar levels in women and probably drive food cravings throughout their cycle. Monitoring daily blood sugar levels may be a method to determine what phase of her cycle a woman is in. This information is especially helpful for those with diabetes.

Menstrual Cycle Phases and Impact on Blood Sugar

The menstrual cycle consists of four phases—menstrual, follicular, ovulatory, and luteal. Different hormonal changes and physical symptoms mark each phase. Understanding the different stages is essential for understanding the correlation between glucose levels and a woman’s hormones.

1. The menstrual phase is the first phase and involves the shedding of the uterine lining, which typically lasts three to seven days. During the menstrual phase, estrogen and progesterone levels are low. The CGM study found blood sugar levels dropped sharply at this phase.

2. The follicular phase begins with the menstrual phase and lasts up to 14 days. During this phase, the follicle-stimulating hormone (FSH) is released, which stimulates the ovaries to produce follicles containing eggs. In the follicular phase, estrogen levels rise and progesterone levels decrease, improving insulin sensitivity and lowering blood sugar levels.

The CGM study found that glucose levels were at a minimum in the late follicular stage. Ongoing research by The Apple Women’s Health Study (AWHS), found that women spend 68.5 percent of the day at a healthy blood sugar level during this phase.

3. The ovulatory phase, which occurs around day 14 of the menstrual cycle, is marked by the release of a matured egg into the fallopian tube for possible fertilization. During the ovulatory phase, estrogen levels peak, which can cause insulin resistance and higher blood sugar levels.

4. The luteal phase, occurs after ovulation and lasts about 14 days. During this phase, the empty follicle transforms into the corpus luteum, which produces progesterone to thicken the uterine lining for possible implantation of a fertilized egg. If fertilization doesn’t occur, the corpus luteum disintegrates, and the next menstrual cycle begins.

During the luteal phase, progesterone levels rise, and estrogen drops, which can cause insulin resistance and higher blood sugar levels. This rise can lead to mood swings, irritability, and fatigue. The CGM study found that glucose levels peaked during the luteal phase. The AWHS found that women spend 66.8 percent of the day at a healthy blood sugar level during this time.

Common Menstrual Cycle Blood Sugar Issues

The changes women experience in their blood sugar levels during their menstrual cycle can lead to a variety of issues. One common one is hypoglycemia, when blood sugar levels drop too low. This can lead to symptoms such as shakiness, dizziness, irritability, and fatigue. A case study from 2022 found that a 40-year-old female patient experiencing chronic hypoglycemia experienced a peak two to three days before menstruation.

On the other hand, some women may experience hyperglycemia, which occurs when blood sugar levels are too high. Hyperglycemia can lead to symptoms such as increased thirst, frequent urination, and blurred vision. Research shows women tend to increase caloric and carbohydrate intake during the second half of their cycle, potentially increasing the risk of hyperglycemia.

Fluctuations and Cravings

When estrogen levels dip during the menstrual cycle, some women may experience cravings for carbohydrates and sweets. Such types of foods can temporarily increase serotonin levels, improving mood and reducing anxiety. The CGM study noted, “positive associations between higher food cravings and higher median glucose levels.”

A 2016 study published in the European Journal of Nutrition found that participants experienced cravings for chocolate, sweets, salty flavors, and an overall significant increase in appetite during their late luteal phase compared to the other stages of their cycle.

Intermittent Fast During Menstruation

Dr. Sarah Bonza, founder of Bonza Health, told The Epoch Times in an email, “[Intermittent fasting’s] impact can vary significantly across different phases of the menstrual cycle due to hormonal influence.” She continues, “The follicular phase might be a more favorable time for intermittent fasting, as estrogen levels rise and can help in managing lower blood sugar levels more effectively. Fasting during this time might be easier metabolically and physically.”

Given the research on elevated glucose levels in the luteal phase, it may not be the best time for women to intermittent fast,  “During the luteal phase … fasting might be more challenging. Women may experience stronger cravings and more intense hunger,” explains Dr. Bonza, “Fasting could potentially exacerbate mood swings, fatigue, or other premenstrual symptoms, making it less ideal.”

A 2023 review showed that intermittent fasting may be harmful to women’s hormonal health if they do not consume sufficient calories. Ultimately, the research on women and intermittent fasting is limited. Every woman is different and may have unique experiences throughout their cycle. When and if to intermittent fast is a personal decision based on several factors.

Dr. Bonza advises, “Monitoring how one feels during fasting in different phases can provide personal insights into what works best. For some, fasting in the follicular phase may enhance physical and mental well-being, while others might find it disrupts their hormonal balance and overall health.”

Managing Blood Sugar During the Menstrual Cycle

Managing blood sugar during the menstrual cycle can be challenging for some women, as hormonal fluctuations can affect all areas of a woman’s life. However, there are certain steps one can take to help manage blood sugar levels:

1. Avoid Sugar and Processed Foods

Sugary drinks and processed foods, such as candy, cookies, and other sweet treats, can cause blood sugar levels to spike quickly and then crash, leading to cravings for more. Catherine Rall, a registered dietitian at Happy V, suggested to The Epoch Times in an email, “Eat a diet with a low glycemic index, which can help to control blood sugar spikes. This includes a focus on getting plenty of fiber and reducing your intake of simple carbohydrates.”

2. Prioritize Protein

Including protein in each meal can help stabilize blood sugar levels. Good protein sources include high-quality meats, fish, eggs, and beans. “Fat and protein work well as energy sources for combatting blood sugar spikes,” explains Ms. Rall.

3. Stay Active

Regular exercise can improve insulin sensitivity and help regulate blood sugar levels. Participants of the CGM study also wore a Fitbit Sense smartwatch during the trial. They found that increased step count is associated with lower blood glucose levels.

4. Choose Vegetables

Opting for vegetables instead of refined carbohydrates like white bread and pasta can help mitigate spikes in blood sugar levels. Additionally, studies show that a compound in cruciferous vegetables may help increase insulin sensitivity, and a 2016 study showed kale can help decrease blood sugar levels.

Ms. Rall advised, “During ovulation and especially during menstruation, cut back even further on the carbohydrates and do more to increase your fiber intake in order to help keep your blood sugar as even as possible.”

5. Get Enough Sleep

A lack of sleep can disrupt your hormones and cause your blood sugar levels to fluctuate. New research suggests women may need more sleep each night than previously believed to help keep their hormones balanced.