Feeling dizzy, shaky, and anxious? It may be more than a reaction to scrolling through social media. It could be a symptom of a sugar crash, aka reactive hypoglycemia.

A sugar crash is more than the lazy feeling you experience at the office after a big lunch. It’s a specific type of hypoglycemia that occurs without having diabetes.

Though it’s often not serious, it can be very uncomfortable and may point to an underlying condition.

What is a sugar crash?

Also known as reactive or fasting hypoglycemia, a sugar crash occurs when blood sugar levels fall below 70 milligrams per deciliter, usually after a meal, according to the American Diabetes Association.

Usually within 4 hours of a meal, reactive hypoglycemia is known as postprandial hypoglycemia.

It’s possible to experience this type of hypoglycemia without having diabetes.


  • dizziness
  • hunger
  • shakiness
  • anxiety
  • confusion
  • increased heart rate
  • irritability


  • prediabetes
  • recent stomach surgery
  • in rare cases, a stomach enzyme deficiency
  • medicines like salicylates, sulfa antibiotics, pentamidine, and quinine
  • serious heart, liver, or kidney concerns
  • low levels of cortisol, growth hormones, glucagon, or epinephrine
  • heavy alcohol consumption
  • pancreatic tumor

How to avoid

  • Eat 15 grams of carbs right after a crash.
  • Eat small meals throughout the day.
  • Limit sugary foods.
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Would a sugar crash by any other name be quite as sweet? Yes. Sugar crashes go by many aliases, including:

  • Reactive hypoglycemia. The symptoms develop a few hours after eating.
  • Fasting hypoglycemia. The symptoms don’t relate to meal times and typically occur due to an underlying condition.

Sugar gets a bad rap, but your brain and body need it to function. There is, ironically, a sweet spot. If blood sugar levels get too high, you’ll get hyperglycemia. Too low, and it goes hypo.

When you experience reactive hypoglycemia, your blood sugar takes a dive. And you don’t feel so good.

Overactive insulin causes sugar crashes. Insulin is a hormone that regulates blood glucose levels in your body. As blood sugar gets higher (like after eating), your pancreas dishes out insulin to lower glucose.

If too much insulin gets out, or your body becomes more resistant to its effects, glucose can suddenly drop. Cue a no-fun sugar crash.

According to the American Diabetes Association, when blood sugar gets below 70 milligrams per deciliter, that’s technically hypoglycemia. This applies whether you have diabetes or not. However, during reactive hypoglycemia, blood glucose may drop to 50 milligrams per deciliter.

Though the symptoms of both are pretty much the same, reactive and fasting hypoglycemia have different causes.

Causes of reactive hypoglycemia

Reactive hypoglycemia happens when your pancreas goes a little insulin happy after a meal and 2 to 5 hours later, you start feeling hypoglycemic symptoms, according to a research review.

Reactive hypoglycemia is a common symptom of prediabetes. If you have prediabetes, your blood glucose levels are high, but not quite high enough to get the full-on diabetes diagnosis.

Prediabetes can be a symptom to help you avoid developing type 2 diabetes by giving you a heads up.

This empowers you to make diet and exercise changes that help keep the “pre” in prediabetes and avoid diabetes altogether.

Causes of fasting hypoglycemia

Fasting hypoglycemia has a few potential and varied causes:

  • Sometimes drinking a bunch of alcohol (especially on an empty stomach) can cause a low sugar episode.
  • Certain medicines can trigger the sugar crash, like salicylates, sulfa drugs, pentamidine, and quinine.
  • It could occur due to low levels of hormones (cortisol, growth hormones, glucagon, or epinephrine),
  • Serious kidney, heart, or liver conditions can cause reactive hypoglycemia. In even rarer cases, a pancreatic tumor may be responsible.
  • According to the National Institute of Diabetes and Digestive and Kidney Diseases, in rare cases, a sugar crash could be a symptom of dumping syndrome. This pretty much only happens if you’ve just had a stomach surgery.

According to the American Diabetes Association, when you have diabetes, your body doesn’t make enough insulin to manage sugar. A hypoglycemic incident can occur if you’ve taken too much insulin or because you’re not eating enough, or if you’re cutting carbs too drastically.

According to a 2013 condition overview, when you have a sugar crash without diabetes, it happens… because. There’s no clear cause for it other than your insulin and glucose going a little bananas.

When to call a doctor

Whichever type of sugar crash you experience, you should call a doctor.

It doesn’t necessarily mean you have anything as serious as a tumor. But since it can be a symptom of something more serious, it’s best to get a checkup and make sure.

The good news about reactive hypoglycemia is you can often avoid it through dietary changes.

And you don’t have to quit sugar forever to avoid a crash. A good reactive hypoglycemia diet is more about balance than cutting out food groups entirely.

Good foods to avoid sugar crashes:

  • Healthy fats. Olive and fish oil, nuts, flax seeds, and avocado have healthy fats that keep you full.
  • Fruits and vegetables. Vegetables are good for you (🙀, right?). Choose fresh produce like leafy greens, tomatoes, onions, and peppers — anything except corn and white potatoes. But those are fine in small amounts.
  • Whole grains. Your body digests whole grains at a slower pace than refined grains. This keeps your blood sugar relatively stable throughout the day. Try limiting highly processed carbs and grains.
  • Lean protein. These might include meats, fish, and beans. Baked chicken, turkey, and fish are great lean proteins. Some vegetarian diets allow eggs, and these are a superb protein option. Many vegetarians don’t eat eggs. And, for the vegans in the house, beans will do the trick.
  • Low fat dairy. Yogurt and cheese are good sources of protein and vitamin B12.

In addition to maintaining this type of reactive hypoglycemic diet plan, it’s good to eat smaller meals throughout the day.

Tucking into a big meal will cause your blood sugar to rise and fall more dramatically, possibly setting you up for a crash. But eating smaller meals throughout the day keeps your blood sugar stable and often wards off reactive hypoglycemia.

These snacks are great for peeps with diabetes.

Symptoms of reactive hypoglycemia are different person to person. According to the National Institute of Diabetes and Digestive and Kidney Diseases, you could have one or more of these hypoglycemia symptoms when your blood glucose lower:

What does reactive hypoglycemia feel like?

The symptoms of a sugar crash come on fast, may be scary, and can make you feel like you’re going to pass out.

Be sure to sit down, eat a small amount of complex carbs, and give yourself a moment to rest.

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Symptoms of reactive hypoglycemia are very similar to diabetic hypoglycemia, though the version accompanying diabetes can be a bit more severe.

Diabetic hypoglycemia symptoms can also include:

  • feeling weak
  • tingling or numbness in your lips
  • coordination problems
  • seizures
  • nightmares

Blood-sugar-induced nightmares don’t sound fun (who needs to dream of dancing pastries with blood-soaked fangs?) So, be sure to maintain a balanced diet and take any prescribed medicine as instructed by your healthcare provider.

Nobody wants to be hungry, confused, or irritable. Just ask people waiting for a table at a restaurant.

Thankfully, sugar crashes are pretty easy to manage. Treatment may vary depending on the cause of the reactive hypoglycemia.

How to treat a sugar crash

According to the American Diabetes Association, when you first recognize a symptom of reactive hypoglycemia, you should eat 15 grams of carbohydrates:

If you don’t have a hard candy around, go for some bread, a banana, or another carb. These will help return your blood sugar levels to normal.

Carbs are the order of the day here. Fats or proteins won’t raise your blood sugar quickly enough. This means your symptoms will hang around longer.

If the symptoms don’t go away in 15 minutes (or if you check your blood glucose, and it’s still under 70 milligrams per deciliter), consume another 15 grams of carbs.

While you’re having this snack, stay seated, drink water, and try to remain calm. The carbs will work their magic and the symptoms will resolve. You can also try to reverse type 2 diabetes.

How to prevent sugar crashes

The best way to prevent postprandial hypoglycemia is to maintain a balanced diet:

By eating like this five to six times a day, you’ll help keep your blood sugar level regular.

You don’t need to cut all sugar. But try to keep the treats to a minimum. Lots of cakes and candies will put you on a blood sugar roller coaster.

Instead, eat fruits to stave off sugar cravings and have your sugary goodies every once in a while.

Sadly, we can’t always be by the kitchen to eat six meals a day. When you’re out and about, be sure to always carry a healthy snack. (Yes, you get to keep emergency snacks. It’s for your health.)

If you have fasting hypoglycemia, it’s also good to follow these dietary ideas but more important to treat the underlying condition. Work with your doctor to find a treatment that prevents sugar crashes.

How to test for blood sugar crashes

If you have a blood glucose monitor on hand, you can test yourself during a crash to see if you’re hypoglycemic. But you need testing from a doctor to get a diagnosis and rule out diabetes as a cause.

If the doctor suspects reactive or postprandial hypoglycemia, you might be asked to do a mixed-meal tolerance test, according to a small research review. Despite the name, it has nothing to do with how much of a stomach ache you get after eating at a restaurant.

Instead, you’ll drink a liquid meal with proteins, fats, and sugar, then have your blood sugar tested multiple times over 5 hours. This tests how your blood sugar reacts when you’re fasting, right after a meal, and hours later.

A doctor will ask peeps with potential fasting hypoglycemia to fast for up to 72 hours. Over those few days, they’ll test your blood sugar multiple times.

Neither of these tests are invasive or painful. They mostly involve a lot of sitting around and, for peeps with fasting hypoglycemia, a rumbly tummy.

These tests will help the doctor determine the exact cause of your reactive hypoglycemia and make sure it’s not a symptom of type 2 diabetes. The diagnosis should come back in a couple of days.

After that, you can start dietary changes right away to avoid future sugar crashes.

Do I need testing after a sugar crash?

It’s important to receive testing after a sugar crash.

This is because reactive hypoglycemia can be a symptom of an underlying condition. Without treatment, it can also lead to diabetes.

Diabetes can lead to heart disease, kidney disease, stroke, and other health concerns, according to National Institute of Diabetes and Digestive and Kidney Diseases.

So, it’s best to get a formal diagnosis and start treating your sugar crashes before symptoms gets worse.

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Sugar crashes can happen even if you don’t have diabetes.

If you get spells of dizziness, irritability, hunger, or an increased heart rate, call a doctor as soon as you can (especially if these spells often happen).

After diagnosis, a balanced diet of complex carbs, healthy fats, and protein can drastically reduce symptoms. Plus, you have a medical excuse to carry around emergency snacks.