My own experiences and experiments
About a year and a half ago, I started having horrible bouts of fatigue a couple of hours after eating breakfast on days that I worked out. Of course, I consulted Dr. Google about my symptoms, and Dr. Google diagnosed me with reactive hypoglycemia. It suggested that I consume sugar when I felt these symptoms, which felt a bit counterintuitive to me as someone with polycystic ovary syndrome (PCOS) who is at high risk for insulin resistance, metabolic syndrome, and type 2 diabetes.
Since then, I've done a bit of digging and experimenting, and this article shares what I've learned.
What is reactive hypoglycemia?
Whenever we eat carbohydrates, our blood sugar levels increase. In response, our pancreas secretes insulin, which tells our cells to take up the glucose. Ideally, this process brings our blood glucose levels back to our baseline in a relatively short period.
Reactive hypoglycemia occurs when too much insulin is secreted, causing too much glucose to be taken up by our cells. This causes glucose levels to plummet.
This graph shows my blood sugar after eating breakfast after a workout. My blood sugar increased, as it should have but then crashed below a healthy range. It took several hours to return to a stable, healthy level.
This graph shows a healthy response to consuming breakfast. Blood sugar rises and then falls back to baseline, without crashing and wobbling before doing so.
This blood sugar crash leads to the symptoms of hypoglycemia which include hunger (hunger is triggered because eating will bring blood sugar levels back up), shakiness and fatigue because our cells now can't easily access glucose from the blood for basic bodily functions, sweating, weakness, nausea, mood swings, anxiety, irritability, headaches, elevated heart rate, and confusion. Sounds fun, right??
Hypoglycemia can also lead to a vicious cycle of blood sugar spikes and crashes because the crashes can cause sugar cravings as your body tries to get blood sugar back up. Consuming sugar or other simple carbohydrates causes another blood sugar spike which causes another insulin spike and potentially another blood sugar crash. Which causes sugar cravings, and... you get the picture!
Causes of reactive hypoglycemia
Diabetes is the most common cause of reactive hypoglycemia because the pancreas in people with diabetes has difficulty producing the right amount of insulin. Increased insulin secretion then causes reactive hypoglycemia. Reactive hypoglycemia can also be an early warning sign of pre-diabetes.
Insulin hypersensitivity can also lead to reactive hypoglycemia. This is essentially the opposite of being insulin resistant. I've learned that I experience insulin hypersensitivity (relative to my baseline level of insulin sensitivity) immediately after exercise. When this happens, the cells have a bigger response to insulin than they should, taking in too much sugar.
Other people experience idiosyncratic reactive hypoglycemia, essentially meaning that it's unclear why it's happening.
I've always had low fasting insulin and blood glucose levels when I've had blood tests done, so I thought I might fall into this last category - I was just an unlucky person experiencing reactive hypoglycemia. Unfortunately, this isn't actually the case.
Reactive Hypoglycemia and Continuous Glucose Monitors
Around the same time that I was experiencing this mid-morning fatigue, I heard a couple of podcasts talking about continuous glucose monitors (You can read all about these in my post on CGMs). I thought they might help me figure out if a) what I was experiencing actually was reactive hypoglycemia and b) why it was happening.
So I took the plunge and invested in a 3-month supply of continuous glucose monitors from Signos.
For the first week or so of wearing a CGM, I noticed that my energy crashes were, indeed, associated with blood sugar crashes, confirming Dr. Google's diagnosis of reactive hypoglycemia.
I was crashing so low that the pre-programmed low blood sugar alerts on the sensor were being triggered to warn me of impending blood sugar doom. I was a bit confused though because my blood sugar was relatively stable otherwise. Even after consuming high carbohydrate loads, when composed of complex carbs, my blood sugar did not increase beyond normal levels, and outside of the post-exercise window, my blood sugar returned to its healthy baseline instead of plummeting too low.
I didn’t understand why my pancreas was sending out too much insulin in the mornings after working out.
And then… I entered the late luteal phase of my cycle. The late luteal phase is what most of us colloquially refer to as PMS. It usually begins a week or so before the start of your period.
This phase started for me on a day when my dog and I were competing in a K9 Nosework trial, so I suspected that my spiking and soaring blood sugar levels were just a result of my competition nerves. I knew that stress could spike blood sugar, so that must have been it. Then the following day, I had to replace the sensor (they are replaced every 10 days). Sensors can take a couple of days to calibrate correctly, so I assumed my erratic readings were the sensor. But after the 48-hour calibration period, my blood sugar levels were still spiking easily and staying high. Even small amounts of carbohydrates, like a handful of blueberries, were causing these sharp and long-lasting spikes.
It wasn’t stress. It wasn’t a new sensor. My blood sugar levels indicated that I had insulin resistance.
Additionally, my fasting blood sugar levels were now in the range that would get me diagnosed with pre-diabetes.
Confused about what had caused this sharp change in blood sugar patterns, I turned to Google. As it turns out, the hormones prevalent during the late luteal phase can lead to an insulin-resistant state, and this is especially common in women with polycystic ovary syndrome and women with diabetes, particularly type I diabetes.
I started using my sensor on Oct. 13, at the very end of my follicular phase. The Signos app records the percent of every day that you spend in the blood sugar range they consider to be ideal for you from a weight loss perspective. This is not necessarily the range you should be in all the time, but the time in this range provides a decent metric for tracking overall blood sugar status. In the days leading up to my period’s arrival on Oct. 29, the app registered a marked increase in time spent outside of their healthy range.
I suspected that this monthly bout of insulin resistance had trained my pancreas to secrete too much insulin. When I'm in the part of my menstrual cycle with high insulin sensitivity, this high insulin sensitivity combined with the extra insulin sensitivity produced by exercise makes my cells super sensitive to insulin. The high insulin levels secreted by my pancreas were then telling my super-sensitive cells to suck up all the glucose, and this caused my blood glucose levels to plummet.
What I Did to Combat Reactive Hypoglycemia
Armed with this information, I decided to adjust how I ate during the last 10 days of my menstrual cycle. My carb sources in this phase of my menstrual cycle exclusively included non-starchy vegetables (see the list below). I cut out beans, fruit, the low glycemic load grains and starchy vegetables was eating during the first two-thirds of my cycle, and of course, sugar and refined carbohydrates. Doing this helped to eliminate the high blood sugar levels I had seen during my previous menstrual cycle, but I was still struggling with reactive hypoglycemia when I re-entered the insulin-sensitive part of my cycle. But I'm pretty stubborn, and I was pretty certain I was on the right track, so I repeated this strategy for the next menstrual cycle.
And indeed, after two cycles of following this carb-cycling pattern, the reactive hypoglycemia went away!
Why Am I bringing This Up Again?
If I "cured" my issue, why am I talking about this again?
Well... with PCOS, your cure only lasts as long as you continue to follow the plan that helped your symptoms go away.
It's a real bummer! I know!
I'm in the middle of some major life upheaval, and the stress has caused a lot of stress eating. Instead of buckling down on my nutrition in those last 10 days of my menstrual cycle, I just kept eating the same foods I always eat, alongside a few more "treats" than is really ideal for me.
And the reactive hypoglycemia is back.
Every morning this week, a couple of hours after breakfast, I have hypoglycemic symptoms including extreme fatigue and brain fog. Your brain needs a ton of energy, so low blood sugar affects it too. It's hard to focus or get work done. I just want to lie down and go to sleep.
So I plan to buckle back down when I enter the luteal phase of my cycle, which should be happening in a week or so. I'll be back to eating all the veggies for a week and a half and saving higher-density carb sources for later. I'm curious to see if it will take two cycles again to get rid of the reactive hypoglycemia or if I've noticed the issue soon enough that I might get it under control sooner. I'll keep you posted!
What does the research say about PCOS and reactive hypoglycemia?
A series of studies have explored reactive hypoglycemia in both lean and overweight women.
Early studies on this topic tried to determine why reactive hypoglycemia was more likely to occur in women with PCOS. One such study purposely induced hypoglycemia by injecting insulin into study participants (Gennarelli et al. 1997). They then measured the physiological responses to this dose of insulin. Hypoglycemia normally registers as physical stress and activates the release of stress hormones like noradrenaline and adrenaline. Participants with PCOS showed lower release of some of these stress hormones compared to participants without PCOS, which may explain why PCOS is a risk factor for reactive hypoglycemia.
Interestingly, some but not all studies find that reactive hypoglycemia is more likely to occur in lean women with PCOS. One study found that about 50% of their lean study participants with PCOS experienced reactive hypoglycemia (Altuntas et al. 2005). These women tended to have lower levels of DHEAS-S, one of the adrenal androgens that is often elevated in women with PCOS, and prolactin, which can also be high in women with PCOS. This study also tested for significant differences in beta cell functions (the cells that produce insulin in the pancreas) using an oral glucose tolerance test but found no differences in beta cell function between those women experiencing reactive hypoglycemia and those who didn't.
A more recent study, however, found that reactive hypoglycemia occurred in about 1 in 6 women with PCOS, which is lower than previous studies, and this rate was the same across lean and obese women (Mumm et al. 2016). This study found that obese participants with reactive hypoglycemia had elevated insulin secretion relative to weight-matched controls without PCOS but lean patients with reactive hypoglycemia had similar insulin secretion as women with similar body weight without PCOS. This finding calls into question why reactive hypoglycemia is occurring in lean women.
Hopefully, future studies will be able to determine the exact cause(s) of reactive hypoglycemia and identify a potential medical treatment for the condition.
Reactive Hypoglycemia and Common Medical Treatments for PCOS
If you have PCOS, your doctor has likely recommended oral contraceptives to help mitigate PCOS symptoms. If you have insulin resistance, it's also likely that your doctor has recommended metformin to treat this insulin resistance (this is a particularly common approach when trying to conceive). One study randomly assigned women with PCOS to take oral contraceptives only, metformin only, or a combination of the two for one year (Glintborg et al. 2017). They then compared the rates of reactive hypoglycemia before and after these medical treatments.
Five out of 23 women taking only oral contraceptives experienced reactive hypoglycemia both before and after the intervention, suggesting no effect of this treatment on reactive hypoglycemia.
Before the intervention, 1 out of 19 assigned to the metformin-only group experienced reactive hypoglycemia. After treatment, 3 out of 19 experienced reactive hypoglycemia, suggesting a possible increased risk of reactive hypoglycemia from metformin.
Similarly, 3 out of 23 assigned to the metformin-oral contraceptive combination group experienced reactive hypoglycemia before the intervention, while 6 out of 23 experienced it after the intervention. Given the lack of effect of oral contraceptives alone, it seems likely that metformin was the driving factor in the shifts experienced in this group.
What can be done to prevent reactive hypoglycemia?
Unfortunately, there is no literature on the prevention of reactive hypoglycemia among women with PCOS. It seems to be more prevalent in insulin-resistant individuals and those with metabolic syndrome, so following a healthy diet and making lifestyle changes that address insulin resistance are likely important.
From my own experience, adjusting my carbohydrate consumption according to my menstrual cycle has been helpful. And now, from failing to continue this plan and experiencing a return of reactive hypoglycemia, I am even more convinced that this plan is effective for me.
If you want to experiment with this yourself, I’d recommend taking the following steps.
Talk to a trusted healthcare provider about what you are experiencing and what you’d like to adjust in your diet.
Gain an understanding of where you are in your menstrual cycle (if you're not already tracking this!). You can read my article on using basal body temperature to track your cycle to learn more about this.
Consider using a continuous glucose monitor to have a better idea of whether your insulin sensitivity is actually varying across your menstrual cycle. Using a CGM will help you identify your specific pattern of insulin resistance, which can vary across women. And to be clear, some women do not experience any changes in insulin resistance across their menstrual cycles. You can learn more about this in my article on insulin resistance across the menstrual cycle. If you’d like assistance interpreting your CGM data, you can schedule a 30-minute CGM session with me.
If you're able to identify a pattern of insulin resistance, during days when your insulin resistance is highest, you'd focus on getting carbohydrates from non-starchy vegetables. During the rest of your cycle, you'd add back in starchy vegetables, low glycemic load fruits, legumes, and low glycemic load grains. See below for suggested food.
This carb cycling plan will likely take a few cycles to be effective because your pancreas will need time to adjust how much insulin it secretes in response to a given amount of carbs consumed.
Another way to combat reactive hypoglycemia in the short is to decrease the amount of carbohydrates consumed in any given meal and/or decrease the glycemic load of the meal (you can learn more about this concept in this article on low glycemic index/load diets. Decreasing the glycemic load of a meal will reduce the amount of insulin secreted and may help to lessen reactive hypoglycemia.
My favorite luteal phase carb sources:
All non-starchy vegetables including asparagus, bell pepper, broccoli, Brussel sprouts, cabbage, cauliflower, carrots, cucumbers, eggplant, fennel, green beans, kohlrabi, lettuce, kale, mushrooms, onion, radishes, spinach, summer squash, Swiss chard, tomatoes, zucchini
My favorite carb sources for the rest of my cycle:
All of the vegetables listed above as well as acorn squash, beets, butternut squash, pumpkin, rutabaga, boiled sweet potatoes, and turnips.
Fruits including apples, avocados, blackberries, blueberries, fresh figs, grapefruit, kiwi, mandarins, nectarines, oranges, plums, raspberries, strawberries, and tangerines.
Grains including black wild rice (sometimes labeled forbidden rice) and quinoa.
Legumes including black beans, cannellini beans, chickpeas, fava beans, great northern beans, green peas, hummus, lentils, mung beans, red beans, and soybeans.
About the author
Kelly Grogan, Ph.D., NTM, is a holistic nutrition therapist who is passionate about helping females with PCOS. She currently manages her own PCOS with nutrition and lifestyle tools that she developed through extensive review of the scientific literature on PCOS interventions.
Disclaimer
This post is not intended to diagnose or treat any medical issues. It is intended for informational purposes only. I am not a medical practitioner. Always consult a trusted healthcare provider with any questions you may have about a medical condition or treatment and before starting any new health care regimen.
References
Altuntas Y, Bilir M, Ucak S, and Gundogdu S. 2005. Reactive hypoglycemia in lean young women with PCOS and correlations with insulin sensitivity and with beta cell function. European Journal of Obstetrics & Gynecology and Reproductive Biology, 119(2):198-205, https://doi.org/10.1016/j.ejogrb.2004.07.038
Gennarelli G, Holte J, Stridsberg M, Niklasson F, Berne C, and Bäckström T. 1997. The counterregulatory response to hypoglycaemia in women with the polycystic ovary syndrome. Clinical Endocrinology, 46:167-174. https://doi.org/10.1046/j.1365-2265.1997.1070915.x
Glintborg D, Mumm H, Holst JJ, and Andersen M. 2017. Effect of oral contraceptives and/or metformin on GLP-1 secretion and reactive hypoglycaemia in polycystic ovary syndrome. Endocrine Connections, 6(4):267-277. https://doi.org/10.1530/EC-17-0034
Mumm H, Altinok ML, Henriksen JE, Ravn P, Glintborg D, and Andersen M. 2016. Prevalence and possible mechanisms of reactive hypoglycemia in polycystic ovary syndrome, Human Reproduction, 31(5):1105–1112, https://doi.org/10.1093/humrep/dew046