Reactive hypoglycemia is when there is a drop in an individual’s blood glucose levels in response to a glucose stimulus. This can be in response to a meal that is high in carbohydrates or after being tested with a glucose drink or mixed meal drink.

Hypoglycemia, on the other hand, is when your fasting glucose is low. Hypoglycemia is a very unusual event and is usually caused by a tumor that produces too much insulin.

Prediabetes and diabetes are characterized by elevated blood sugar upon fasting and elevated blood sugar after drinking or eating. The first early symptom of type 2 diabetes is imbalanced blood sugar levels. Dr. Seale Harris, who studied hypoglycemia, believed that patients with reactive glycemia were the diabetics of tomorrow.

Your cells rely on blood glucose for energy.

Our bodies need glucose to function properly. We get glucose from the foods that we eat, such as carbohydrates, like fruit, bread, and rice.

While blood glucose levels can vary depending on the individual, typically your blood glucose levels will dip before eating a meal and rise after you’ve eaten. Your body breaks down carbohydrates and then transports glucose in the bloodstream to your cells. In order for your body to properly use and distribute the glucose, your body needs insulin.

Insulin is a hormone excreted by the pancreas. After you eat and your glucose levels rise, the cells in your pancreas release insulin into the bloodstream. Insulin helps move glucose into the cells, which helps lower the glucose levels and return the body to a state of homeostasis. Some glucose is used for energy, and cells in your liver and muscles store excess glucose as a substance called glycogen. The liver will release glycogen in times of need such as when you are fasting and your blood glucose levels dip.

This cycle continues: After you eat, your glucose levels rise, causing your pancreas to produce insulin, which then helps glucose enter the bloodstream and tries to keep it in normal range.

In a case of reactive hyperglycemia, upon finishing a meal, you experience an abnormal spike in blood glucose levels, followed by an excess production of insulin released by the pancreas. This overproduction of insulin continues after the glucose has been digested from the meal, causing the blood glucose levels to fall below a normal range.

The true incidence is not known, but I believe it could be upward of around 40 to 50 million, and maybe even higher. In 2015, it was estimated that 84.1 million people had prediabetes or insulin resistance. And I think many of those individuals with prediabetes may also have reactive hypoglycemia.

Reactive hypoglycemia is relatively undiagnosed because most of the time we check only fasting blood work. And we often don’t check blood glucose levels under stress, be it from a meal or a glucose tolerance challenge (more on this later).

While there isn’t much data on gender differences, in my practice, I have found reactive hypoglycemia to be more common in women than in men, and in people between the ages of thirty and fifty. That may also be a bias in people seeking treatment, so it’s hard to tell.

Common symptoms include dizziness, lightheadedness, palpitations—especially at rest—anxiety, trouble concentrating, memory issues, difficulty with sleep, and, very interestingly, vivid dreams. In my patients I have seen a tremendous correlation with reactive hypoglycemia and vivid dreams or nightmares.

These symptoms can be present daily and may be more common in the late morning, midafternoon, or evening. They also can be felt a few hours after eating a meal, when blood glucose levels drop. And the symptoms may last longer, so sometimes people may not recover between meals.

Another important connection is stress, which can trigger these symptoms as well. Our levels of stress, which are related to our cortisol levels, can affect our glucose levels. I have noticed that when women are getting close to their period and reporting increased levels of stress, there may be an increase in glucose intolerance. And there may be some rhythm with the symptoms that patients are experiencing. These symptoms may occur at the same time every day or the same time every month or in the midst of stressful times, etc.

I’ve also seen some men who are going through a stressful period whose symptoms can last a month or longer. The symptoms can be exacerbated when there is more volatility in the blood glucose levels. So if a patient isn’t sleeping well, is dealing with a lot of stress, is having trouble concentrating, then their blood glucose levels may be going up and down. The patient may be having those signs of volatility multiple times a day for a long period of time. It can feel like the symptoms are always there, and therefore it may become accepted as a way of life. I think that’s what makes it difficult for people—they don’t realize that there is something going on a lot of the time.

I think reactive hypoglycemia may often fall under the larger category of insulin resistance, which has a genetic component.

Also, when I see women, I often see a common thread of digestive issues, an underactive thyroid, and blood sugar regulation issues all together. For example, a lot of the time when women are close to their period, they experience more symptoms of fatigue, constipation, bloating, etc. And if you have these symptoms, the blood sugar is going to be affected as well.

More on the connection to women’s hormone levels: In terms of how estrogen plays a role, I had a patient recently who was having symptoms of reactive hypoglycemia, which resolved when she stopped the oral contraceptive pill. When you look at the side effects associated with oral contraceptives, glucose intolerance is listed. I think having a baseline prior to going on oral contraceptives can make it easier to think about which type of oral contraceptive, with what level of estrogen or progesterone, you may want to take. Traditionally we always would start the pill and ask questions later.

Polycystic ovary syndrome (PCOS) also has an interesting connection. With PCOS, people look at it two different ways. Some doctors will view it as a hormonal imbalance alone, and others may look at it as insulin resistance. If you think about PCOS in terms of insulin resistance, it means that your pancreas is overproducing insulin to handle a certain glucose level. The end result of overproducing that insulin is going to be reactive hypoglycemia. That excess insulin is going to take what could be a relatively normal starting glucose point and bring it down further than it should, below the point of your baseline or your fasting level.

Even if you don’t have PCOS, if you’re experiencing volatile blood sugar levels, the body has to produce more cortisol, which is going to affect your progesterone levels, which may in turn affect your fertility. If your blood sugar is very volatile, your body’s under more stress and your hormones are going to be affected by that alone.

I have often seen reactive hypoglycemia and thyroid issues go hand in hand, particularly in female patients. One of the reasons that the thyroid is so important is that it impacts the body’s ability to handle low blood sugar, and one of the main ways the body handles low blood sugar is through a process called gluconeogenesis. This breaks down proteins in the muscle, and that tends to be impaired in people with an underactive thyroid. The other aspect is that digestion’s slower, and so you’re more likely to have constipation with an underactive thyroid. So that will also affect the body’s ability to handle glucose regulation or glucose metabolism.

Reactive hypoglycemia can be connected to your digestion in a couple of other ways. If your digestion is slow, for example, and you eat something, as soon as that glucose, or food, enters your mouth, your body responds by saying, “Hey, I got to handle it.” The pancreas gets kicked into gear, but if that glucose or food is delayed, you may have all this excess insulin floating around without glucose to match. And your blood sugar will often drop, which can make it worse.

Overall, I think we miss the proper diagnosis when patients seek help based on a single system. People may look specifically at the thyroid, or look specifically for high-blood sugar levels, or look only at their digestion. They’re not saying, “Oh, okay. Maybe it’s multiple systems that are involved.” I think that can be why people are not diagnosed soon enough, because diagnoses are becoming more and more complex across different areas.

The best way to diagnose it is to do an oral glucose tolerance test or a mixed meal tolerance test. These measure a patient’s glucose levels and can show how much insulin the pancreas produces in response to the glucose stimuli.

The oral glucose tolerance test involves taking a sample of the patient’s fasting glucose levels, then having them drink a seventy-five-gram syrupy glucose solution. The patient’s blood is drawn one hour after ingesting the drink, and then another hour after that.

The mixed meal tolerance test involves getting an IV that will be used to draw various blood samples over the course of two hours. The patient drinks a liquid meal (like Boost or Ensure), which contains fats, protein, and carbohydrates, and their blood is sampled every thirty minutes for two hours.

Typically what you’re looking for is a change in their insulin level and a drop in the blood glucose levels, below the fasting level, within a few hours.

We also look at their hormone levels and thyroid levels, since the two may be connected to reactive hypoglycemia.

I think one reason reactive hypoglycemia can be overlooked is because, typically, individuals come into the office and get their fasting blood tests done. But fasting is not the most common state we’re in. In fact, it’s actually rare, since we’re really only fasting for maybe a few hours a day. More commonly, we’re postmeal. And we never really say, “Come in two hours after you eat to see if you are diagnosed.”

Another thing is that as medical professionals, we’re often trained to only look at the high numbers on lab tests, looking for prediabetes or type 2 diabetes. People are usually more concerned with looking for high levels—either being diabetic or having high blood sugar levels—and overlook whether their blood sugar levels are low.

Doctors also don’t usually measure insulin levels. If they do measure a patient’s glucose levels and those appear to be normal, this could be misleading because it’s just one data point. A person’s glucose levels could be normal at one moment, but if their insulin levels are inappropriately high, the insulin will remain in the system, causing subsequent blood glucose levels to continue to drop lower and lower over time. The person could experience symptoms after the blood test yet not realize there is an issue since the numbers from that first test seemed fine.

For example, if a patient measures a glucose level of 80 and their insulin levels are high, their next test—if taken—could measure 60. If you measure at only one point in time, you won’t be able to see how their insulin levels will affect their glucose levels in the future.

We don’t collect enough data points, and we really collect only one number, which is why in my practice we stress these more-comprehensive tests. Most doctors base treatment on one number, when in reality, one number in the grand scheme of a person’s life is a pretty small sample size. I think to do a proper diagnosis you need two points: a fasting level and then another one after you do some form of a challenge test.

I have seen a lot of people that come in and say, “I have these symptoms, but I don’t understand because my blood work looks normal. And I’ve had it tested several times.” But the problem is that it was tested the same way each time, so they’re not testing under stress.

For example, when we look for heart disease, what do we do? We do a stress test. We get on the treadmill and see how the heart responds when it’s stressed. People may not have the symptoms at rest, and they may not have been diagnosed with heart disease at rest, but when they’re exercising or their body is stressed, those changes come about. I would look at blood sugar in almost the same way—that really you don’t make a proper diagnosis until you stress the body and actually see: “Oh, my blood sugar is not reacting properly. It’s not responding the way it should.” It’s challenging the metabolism in a different way.

Also, everyone’s blood sugar tolerance level may be different. There isn’t one number that is a set point diagnosis. If it’s very low, such as a blood sugar level of 50 mg/dl, it could be very obvious and we would be able to make that diagnosis. However, someone with a blood sugar of 80 may feel fine, whereas someone else with a fasting blood sugar level of 150 who now has a level of 80 may be experiencing severe symptoms. The symptoms don’t correlate necessarily with the number itself. Without that second data point, we don’t know the volatility. And more than anything else, it’s really the volatility that makes a difference.

I give people a questionnaire to fill out before they come in that asks them about fifty possible symptoms. I do this because when people take the time to think about the symptoms, they may realize how many of the symptoms they’re experiencing are related. People may think of only one or a few main symptoms that are most problematic, and they may not realize that there are other ones present that may highlight an underlying problem.

When teaching people to balance their blood glucose levels, I tell them to look at how carbohydrates, proteins, and fats work together. In general, 100 percent of carbohydrates become glucose, with fiber being an exception in some cases. While it depends on the individual, a lot of people don’t realize that protein—upwards of 40 to 50 percent of your meal—can become glucose as well. It’s important to balance our meals with protein and fat and not have carbohydrates by themselves.

For the average person, an ideal meal would be the 1:1:1 diet. For one serving of protein, there should be one serving of carbohydrates and one serving of fat. For example, in a 1,700-calorie-per-day diet, it would be 100 grams of protein, 100 grams of carbohydrates, and 100 grams of fats.

While I typically advise people with reactive hypoglycemia to adopt a higher-fat or low-glycemic (low-carbohydrate) diet, it varies based on the individual’s weight. For example, if someone is overweight and has reactive hypoglycemia, they may adjust their diet to lower their carbohydrates and lose weight at the same time. Restricting carbohydrates should be done cautiously though, especially if a patient is very thin, because then you’d want to avoid losing weight. You also don’t want their body to be put under stress, which would mean they couldn’t access the energy from protein and fat as quickly as they’d need to.

It’s always a good idea to avoid refined-sugar-based products. That said, I have found that many people react more strongly to and have intolerance issues with complex carbohydrates like flour and other starches. It may be because of the complex digestive issues that go along with this. Foods that have yeast or gluten in them may be harder for the body to break down.

In terms of supplements, chromium has been found to be helpful with reactive hypoglycemia. You can’t metabolize sugar without chromium or fat in your body. For approximately every hundred grams of sugar, you need about a hundred micrograms of chromium. So chromium is a very important supplement right off the bat.

Vitamin D may also be helpful with insulin sensitivity, as it helps to regulate blood glucose levels better.

Alpha lipoic acid is another supplement that may help with insulin sensitivity.

One of my favorites is magnesium. Magnesium seems to have an effect on many different systems. Magnesium is very important for the elasticity of blood vessels, and insulin in glucose metabolism doesn’t work without adequate magnesium. It’s worth noting that taking calcium can deplete magnesium levels, so you should be careful not to take too much calcium.

Another surprising supplement that may affect insulin sensitivity is probiotics. When bacteria in the gut is imbalanced, people have trouble breaking down glucose. And researchers conducted a study in which mice were given beneficial bacteria, which led to decreased insulin resistance.