Do glucose levels in the brain drive hot flashes?
Research shows a relationship between the high blood sugar and hot flashes. Stabilizing glucose levels might help ease the discomfort.
A rolling heat spreads uncontrollably over your skin. Your heart beats faster. Your skin flushes hot and red, you start sweating through your clothes, and you feel confused and irritable. A hot flash has taken over your body, and all you want to do is find somewhere cool to wait it out.
Almost 80% of people undergoing natural menopause have hot flashes and about 30% report frequent or severe symptoms. These are called vasomotor episodes (because they’re related to constriction and dilation of the blood vessels), and researchers attribute them to ovarian changes in early menopause that cause spikes and dips in how much estrogen the body produces. So what is the relationship between blood sugar and hot flashes, and does elevated blood sugar cause hot flashes?
Although researchers don’t know exactly what role glucose plays in triggering these effects, there is pretty strong evidence from large studies that metabolic conditions like insulin resistance and diabetes seem to make them worse, suggesting that blood sugar and hot flashes are related. While other research suggests these symptoms are the result of too little glucose in the brain because of changes in glucose transport during menopause, this does not likely mean that more glucose is better during menopause. (In fact, post-menopausal women already have an increased risk of metabolic disease.)
Rather, it’s more likely that the changes that lead to that glucose shortage, combined with the effects of insulin resistance, make the brain less able to use glucose effectively. Maintaining stable glucose levels over time through healthy diet and lifestyle may be your best bet for managing menopause symptoms.
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The Links Between Metabolic Health and Menopause
There is substantial research on the links between vasomotor symptoms and metabolic diseases. Not all the research agrees, but some large, longitudinal studies find significant correlations.
So what is the link between sugar and hot flashes? A study of about 150,000 postmenopausal women, followed over 20 years, linked hot flashes and night sweats with an 18% increased likelihood of diabetes. The correlation was higher in patients with more frequent and severe symptoms. Another study of more than 3,000 overweight women followed for eight years linked hot flash symptoms to higher insulin resistance and fasting blood glucose levels.
In a study of 17,000 postmenopausal women, researchers saw that eating a diet low in fat and high in vegetables, fruits, and whole grains can decrease hot flash frequency. In some cases, they saw that weight loss of ten pounds could potentially eliminate vasomotor symptoms. Weight loss and healthier diets improve insulin sensitivity, which promotes better glucose control.
> “A more effective strategy to mitigate hot flashes might be to improve insulin sensitivity by stabilizing glucose levels over time and keeping glucose in a healthy range.”
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Why Menopause Symptoms Are Connected to Metabolic Dysfunction
Research has not yet fully explained the link between increased menopause symptoms and metabolic dysfunction like insulin resistance. The two conditions share some risk factors, such as elevated BMI, but those factors alone don’t seem to explain the connection.
Hot flashes set off the autonomic nervous system, which regulates our basic bodily functions like temperature. During a hot flash, heart rate and blood flow to the skin increase, skin temperature spikes, and then plummets as the body starts giving off heat.
The autonomic nervous system also plays a role in glucose regulation, so one theory is that the autonomic system changes present in hot flashes are also associated with increased glucose and decreased insulin production.
Another hypothesis is that night sweats disrupt sleep, and getting poor sleep or not enough sleep can throw off our body’s ability to process glucose effectively. One observation that may bolster this theory is that women whose symptoms lasted longer—meaning they had longer periods of disrupted sleep—had greater risk of diabetes.
A Novel Theory: The Brain, Glucose and Menopause
Researcher Sharon Dormire, PhD at Texas A&M, also studies the potential link between blood sugar and hot flashes. Glucose levels in our body can be impacted by everything from daily sleep, exercise, diet, and stress levels, as well as overall insulin sensitivity. In studies on humans in experimental settings, Dormire has seen people experience fewer hot flashes after eating, and more hot flashes when blood glucose falls between meals.
Dormire hypothesized that changing estrogen levels causes a drop in the amount of a glucose-transporting protein made in the blood-brain barrier. These changes would decrease the rate at which glucose is transported into the brain, causing dips in its energy resources. Dormire’s theory is that this lack of energy activates the autonomic nervous system and triggers a hot flash, releasing glucose and providing the brain with much-needed fuel.
A small experimental study by Dormire analyzed ten postmenopausal women who stopped taking hormone therapy and experienced hot flashes. When their blood glucose was over 130 mg/dl—above a normal range—the women were much less likely to have hot flashes than when their blood sugar stayed below 110 mg/dL.
Dormire is currently using continuous glucose monitoring and hot flash monitors to test this idea. She has patients come into the lab and perform cognitively strenuous tasks to see if they trigger hot flashes. So far, Dormire said, she’s seen that these challenging psychological tests can effectively stimulate a hot flash when a patient is fasting, and therefore has lower glucose levels. Though this research is yet to be peer-reviewed or published, it may further the theory of the connection between blood sugar and hot flashes.
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What Does This Mean for Menopause and Glucose?
The studies linking insulin resistance with worse menopause symptoms seem to contradict Dormire’s theory that hot flashes are due to low glucose in the brain: People with hot flashes tend to be more likely to develop insulin resistance, yet those same people tend to have higher glucose levels.
What is important to remember is that insulin resistance in the brain makes it harder for brain cells to transport glucose into brain cells to produce energy. So even though someone with insulin resistance may have more glucose in their blood, that extra glucose still may not be making it to the brain to supply adequate energy.
With this in mind, a more effective strategy to mitigate hot flashes might be not to increase glucose levels through diet or more frequent meals, but might rather be to improve insulin sensitivity by stabilizing glucose levels over time and keeping glucose in a healthy range. Sharp spikes and dips in blood glucose tend to promote insulin resistance over time and stimulate the autonomic stress response in the body.  Keeping glucose elevation after meals low by choosing foods that have less of a glycemic impact, in addition to other insulin-sensitizing strategies like getting adequate sleep, managing stress, and exercising regularly, could over time allow the brain to be more responsive to the glucose circulating in the body.
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Fasting blood sugar levels classify into 3 categories: normal, prediabetes, and diabetes. To be considered 'normal,' fasting glucose must be under 100 mg/dl.
While there are many gaps in our knowledge about blood sugar and hot flashes, we know some behaviors can help mitigate them. Hot flashes are more common in smokers and people with higher BMIs, and some research notes stress, spicy food, and red wine as triggers. If you’re having frequent or severe hot flashes or episodes of night sweats, check with your doctor for other signs of metabolic syndrome and diabetes.
Although more research needs to be done on the links between metabolic health and menopause—including the relationship between blood sugar and hot flashes—the basic science is so far a hopeful indicator that by improving insulin sensitivity, and keeping blood sugar levels stable throughout the day so as not to trigger an autonomic response, it might be possible to prevent or ease hot flashes and night sweats.
Jennifer Welsh is a Connecticut-based science writer and editor with over ten years of experience. Before becoming a writer and editor, Jen spent several years at the lab bench, doing hands-on cancer research, then joined the team of an antiviral drug discovery startup. Jennifer’s goal as a science communicator is to clearly and concisely share quality, accurate information to help make your life healthier and happier.
She’s previously worked and written for WIRED Science, The Scientist, Discover Magazine*, LiveScience, and Business Insider. She has a bachelor’s degree in Biological Sciences from The University of Notre Dame and a Graduate Certificate in Science Communication from the University of California, Santa Cruz.*
