Ever notice bigger glucose spikes around your period? Wonder why you're dealing with relentless chocolate cravings one week and then feeling energized and clear-headed the next?
Chances are good your hormones have something to do with it. Of course, these natural changes aren't a problem to fix; they're patterns that reveal your body (and hormones) at work.
But by understanding how your glucose patterns change throughout your cycle, you can find ways to work with the hunger, cravings, energy dips and more.
Hormones 101
Estrogen, the primary female sex hormone, has protective effects on insulin sensitivity (how well your body is able to use insulin to manage your blood sugar); therefore, women tend to have better insulin sensitivity during their reproductive years, partly due to estrogen.1 When estrogen is high (particularly during the first half of your menstrual cycle), your cells absorb glucose easily and blood sugar stays relatively stable.
Progesterone, has the opposite effect. As progesterone rises in the second half of your cycle, insulin sensitivity drops. Your cells become less responsive to insulin, which means more glucose lingers longer in your bloodstream after meals. Energy also feels unpredictable and cravings may increase.
And while progesterone might seem like it’s trying to sabotage your metabolic health, what’s actually happening is that the luteal phase is the monthly dress rehearsal for pregnancy. That extra glucose in your bloodstream? If you were pregnant, it would cross the placenta to feed a growing fetus. Your body doesn’t wait for a positive pregnancy test; it starts prepping from the moment ovulation happens, even if you aren’t pregnant.
While it might seem easy to see estrogen as “good” and progesterone as “bad” for your metabolism, they simply do different jobs at different moments of your cycle. Understanding this can help you make sense of your CGM data and patterns.
Your Glucose Response is in Your Head (Literally)
…or, more accurately, your brain. If you’ve ever dealt with cravings around your period, a 2023 study reveals why. This study used intranasal insulin delivery (essentially spraying insulin into the nasal cavity where it crosses the blood-brain barrier) to measure how the brain responds to insulin across the menstrual cycle.2 As a reminder, your body releases the hormone insulin in response to glucose in your bloodstream to help pull it out and into your cells where it can be put to use for energy.
During the first half of your cycle (aka the follicular phase) the brain responded strongly to insulin. It adjusted hunger signals accordingly and helped regulate how much glucose the body stored versus burned.
It was during the second half of the cycle (the luteal phase) that brain insulin sensitivity dropped significantly. The brain no longer heard the insulin signals as clearly, and when the brain can’t register how much glucose is available, it does the next logical thing: it tells you to eat more.
So those luteal-phase cravings that make you dream of sugar and carbs? You aren’t imagining it, and it’s just not a matter of willpower. Your brain is operating with limited metabolic awareness, and it’s not getting the memo that there is plenty of glucose already in circulation, so it starts dishing out hunger signals.
But why do our brains do this? Researchers think it might be evolutionary. During the follicular phase, your body is directing energy toward high-energy demanding tasks like building the uterine lining, which requires efficient glucose use. During the luteal phase, the priority shifts to energy storage, in case of pregnancy.
Sure, knowing this doesn’t make the cravings go away, but it can help you understand where your cravings are coming from and that there is a biological, brain-based component at play, not a shortcoming.
The Hormone-Blood Sugar Connection, Phase By Phase
An average menstrual cycle lasts anywhere from 27-35 days, but for the sake of simplicity, we’re going to share information that coincides with a 28-day cycle. Period tracking apps or wearables can help you determine your average cycle length.
Follicular Phase (Days 1-14)
Your period starts this phase, and while the first few days might feel rough, things should improve quickly. You may also notice a sharp drop in glucose that coincides with menstruation (usually within the first 2-4 days).3
During this phase, estrogen is climbing and insulin sensitivity is high, meaning blood sugar tends to stay lower and more stable after meals. You may also notice that you’re less hungry compared to the second half of your cycle.
This is also when your muscles are most efficient at pulling glucose out of the bloodstream for fuel. Research suggests that resistance training during the follicular phase may lead to greater gains in muscle strength and size compared to the same training during the luteal phase.4 So if you're going to push it in the gym, this is the most ideal time.
Ovulatory Phase (Around Day 14)
Estrogen peaks right before ovulation, and you get a surge of luteinizing hormone (LH), the hormone that triggers ovulation. For a brief window, insulin sensitivity is still high, but there is a gradual increase in glucose levels during ovulation compared to the late-follicular phase.5 You may feel sharper and more energized during this phase.
Cognitive performance is also at its highest during this window thanks to testosterone hitting its peak during ovulation. Research found that women had their fastest reaction times and made fewer errors on the day of ovulation, with more active women having even better cognitive performance than those who weren’t active.6
However, once the egg is released, estrogen decreases, and progesterone levels increase, shifting your metabolism. Some women see a small glucose bump around ovulation itself. If you notice a day or two of slightly higher readings mid-cycle on your CGM, it could be a sign of ovulation.
Luteal Phase (Days 15-28)
Estrogen has dropped and now progesterone is running the show, which means that your cells are generally less responsive to insulin right now. As a result, you may start to notice:
- Increased hunger and cravings (especially for carbs and sugar): this is driven by reduced brain insulin sensitivity, not a lack of discipline
- Higher post-meal blood sugar: the same foods you consumed in the first half of your cycle may produce a different glucose response during the luteal phase
- Energy dips and mood shifts: this is related to both hormonal changes and natural blood sugar variability
- More glucose variability throughout the day: you may notice more spikes, more dips, and less stable ranges
And if you’re concerned about carbs spiking your blood sugar, one study found that the increase in carbs consumed (around 6g/day more in the late luteal phase) didn’t account for the rise in glucose, which means that the glycemic shift during the luteal phase is primarily hormonal, not dietary.3
Birth Control and Blood Sugar
So what happens to blood sugar when you are on hormonal contraception? A lot depends on the type of birth control you’re using. An older study found that combined birth control pills (estrogen + progestin) reduce insulin sensitivity by 30-40%, while progestin-only formulations didn’t affect insulin resistance (when your cells start to struggle to effectively pull glucose out from your bloodstream) at all.7
Levonorgestrel and desogestrel formulations (synthetic hormones used in birth control) result in the body dealing with more insulin than it otherwise would. Levonorgestrel does so by increasing levels by about 60-90%, while desogestrel clears insulin from the bloodstream about 25% slower. So if you’re on birth control, you may notice bigger or wider postmeal spikes on your CGM than you do on your pill-free week.8
A 3-year longitudinal study tracked 703 women on Depo-Provera (birth control shot), low-dose birth control, or non-hormonal methods.9 Depo-Provera users (but not low-dose birth control users) had slightly greater increases in glucose and insulin, with a steady increase in glucose throughout the first 30 months, which then leveled off after that. Insulin levels also increased for the first 18 months, then leveled off. These elevations were slightly more pronounced in women who were considered overweight or obese.
What About Perimenopause and Menopause?
The average age of menopause is 50 years old, but women can develop symptoms of perimenopause as early as their 30s. Perimenopause is marked by a chaotic, sustained decline in hormones, which can lead to a metabolic slowdown and an increased risk of insulin problems. During this phase, which can last over 10 years, women are at a higher risk of developing metabolic syndrome (a cluster of elevated markers that put you at risk of heart disease, type 2 diabetes, and stroke), compared to women who are already post-menopausal.11 If you’re in perimenopause and have higher insulin levels, you may also experience more severe hot flashes and night sweats.12
Interestingly, women taking oral estrogen plus progesterone hormone replacement therapy (HRT) have higher glucose utilization and insulin sensitivity than women not on HRT.11 And a more recent meta-analysis found that both oral and transdermal HRT reduced insulin resistance in healthy postmenopausal women.13
Cycle-Friendly Tips for Supporting Your Blood Sugar
The goal isn’t to overhaul your life every two weeks. It’s normal for glucose to fluctuate throughout your cycle, and these tips are designed to help you work with your blood sugar:
Track for patterns, not perfection: If you have a CGM, start noting where you’re at in your cycle alongside your glucose data. You may notice that the same meal gives you a totally different response depending on the week. This isn’t a problem that you need to fix, just a pattern to note. Remember, hormones can be the reason for glucose changes in the luteal phase, not necessarily carbs.
Experiments with carbs: Want to understand how your body actually responds to a specific food? Try it during the follicular phase first, when insulin sensitivity is higher and hormonal interference is lower. Then try it again in the luteal phase. The difference tells you something about your cycle's metabolic impact, not about whether the food is 'good' or 'bad. You may also wish to experiment with slightly increasing carb intake during the luteal phase, if you’re active for example, to boost exercise performance.
Protect sleep (especially in the luteal phase): Research shows that getting 90 fewer minutes of sleep per night for six weeks or more can increase the risk of insulin resistance by 15%, with effects even more pronounced in postmenopausal women.14 That's a big deal, especially during the luteal phase when insulin sensitivity is already lower. Progesterone can sometimes disrupt sleep quality during this window, due to its effect on raising core body temperature, so this is when practicing optimal sleep hygiene (a wind-down routine, sleeping in a cool room, consistent sleep-wake cycles) can improve sleep quality and support a healthy metabolism.
Get moving after meals: Short bursts of activity can help glucose enter cells even when insulin sensitivity is lower. A 15-20-minute walk after a meal during your luteal phase may help reduce subsequent spikes. Also, experiment with walking after a meal versus before one to see which has a bigger impact on your blood sugar.
Eat protein and fiber before carbs: Food order matters more when insulin sensitivity is lower (aka, during the luteal phase). Eating a handful of nuts, a side salad, or some chicken before potatoes or pasta could help blunt your glucose response. Play around with food order and compare how you feel with what your CGM data reveals.
Tackle sugar cravings: Those 3pm chocolate cravings hit different during your luteal phase, but adequate magnesium helps support insulin sensitivity and stabilize glucose metabolism. So reach for some dark chocolate, pumpkin seeds, almonds, or cashews instead of ignoring the craving.
Final Thoughts
Your cycle isn’t one-size-fits-all; maybe it’s 27 days, maybe 33. Some luteal phases hit hard; others barely make a ripple. The only way to truly understand how your blood sugar shifts alongside it is to see the pattern for yourself.
That’s where a continuous glucose monitor, and the Signos app, changes everything. Instead of guessing, you can watch your glucose levels unfold in real time, mapped directly alongside each phase of your cycle. You’ll see how food, movement, stress, and sleep interact with your hormones day by day, turning the question of “is it my hormones?” into clear, actionable insight.
Because when you can see the connection, you can finally work with your body, not against it.
Topics discussed in this article:
References
- Ciarambino, T., Crispino, P., Guarisco, G., & Giordano, M. (2023). Gender Differences in Insulin Resistance: New Knowledge and Perspectives. Current Issues in Molecular Biology, 45(10), 7845.
- Hummel, J., et al. (2023). Brain insulin action on peripheral insulin sensitivity in women depends on menstrual cycle phase. Nature Metabolism, 5(9), 1475-1482.
- Li, Z., Yardley, J. E., Zaharieva, D. P., Riddell, M. C., Gal, R. L., & Calhoun, P. (2024). Changing Glucose Levels During the Menstrual Cycle as Observed in Adults in the Type 1 Diabetes Exercise Initiative Study. Canadian journal of diabetes, 48(7), 446–451.
- Kissow, J., Jacobsen, K. J., Gunnarsson, T. P., Jessen, S., & Hostrup, M. (2022). Effects of Follicular and Luteal Phase-Based Menstrual Cycle Resistance Training on Muscle Strength and Mass. Sports medicine (Auckland, N.Z.), 52(12), 2813–2819.
- Lin, G., et al. (2023). Blood glucose variance measured by continuous glucose monitors across the menstrual cycle. Npj Digital Medicine, 6(1), 140.
- Ronca, F., et al. (2025). Menstrual Cycle and Athletic Status Interact to Influence Symptoms, Mood, and Cognition in Females. Sports Medicine - Open.
- Godsland, I. F., Walton, C., Felton, C., Proudler, A., Patel, A., & Wynn, V. (1992). Insulin resistance, secretion, and metabolism in users of oral contraceptives. The Journal of clinical endocrinology and metabolism, 74(1), 64–70.
- Godsland, I. F., Walton, C., Felton, C., Proudler, A., Patel, A., & Wynn, V. (1992). Insulin resistance, secretion, and metabolism in users of oral contraceptives. The Journal of Clinical Endocrinology & Metabolism, 74(1), 64–70.
- Berenson, A. B., Williams, K. J., & Rahman, M. (2011). Effect of injectable and oral contraceptives on glucose and insulin levels. Obstetrics and Gynecology, 117(1), 41.
- Choi, M. J., & Yu, J. (2025). Menopause and Diabetes Risk Along with Trajectory of β-Cell Function and Insulin Sensitivity: A Community-Based Cohort Study. Healthcare, 13(9), 1062.
- Athar, F., Gregory, S., Houston, E. J., & Templeman, N. M. (2025). Insulin levels early in perimenopause inform vasomotor symptom incidence across the menopausal transition. medRxiv.
- Bitoska, I., Krstevska, B., Milenkovic, T., Subeska-Stratrova, S., Petrovski, G., Mishevska, S. J., Ahmeti, I., & Todorova, B. (2016). Effects of Hormone Replacement Therapy on Insulin Resistance in Postmenopausal Diabetic Women. Open Access Macedonian Journal of Medical Sciences.
- Faubion, S. S., & Jiang, X. (2024). New meta-analysis shows that hormone therapy can significantly reduce insulin resistance [Press release]. The Menopause Society.
- Zuraikat, F. M., Laferrère, B., Cheng, B., Scaccia, S. E., Cui, Z., Aggarwal, B., Jelic, S., & St-Onge, M. P. (2024). Chronic Insufficient Sleep in Women Impairs Insulin Sensitivity Independent of Adiposity Changes: Results of a Randomized Trial. Diabetes care, 47(1), 117–125.
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