What Is Hypoglycemia?

Definition

Hypoglycemia, or low blood glucose, occurs when the amount of glucose (or sugar) in your blood is too low (less than 70 mg/dl). This level matters because glucose is the main source of energy for the cells in your body. Hypoglycemia is more common in people living with diabetes, but it can also happen to people without diabetes. 

Sometimes people feel what they call a “sugar crash” a few hours after eating a meal that’s high in carbohydrates. This is different from hypoglycemia because these people usually have normal blood glucose levels.

Low blood glucose is very rare in healthy people. That’s because the body is skilled at making adjustments to keep blood glucose within a normal range.

So when an otherwise healthy person has low blood glucose — non-diabetic hypoglycemia — it’s usually a sign that something else is going on.

While they sound similar and can have overlapping symptoms, hypoglycemia isn’t the same as hyperglycemia, or high blood sugar. The best way to know what’s going on is to check your blood glucose level with a glucometer (a device that measures glucose levels).

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Causes

Diabetes is the most common cause of hypoglycemia, including Type 1 diabetes (T1D), Type 2 diabetes (T2D), and gestational diabetes. People who live with diabetes work to keep their glucose within target range by balancing medications, food, and exercise. Managing blood glucose levels with diabetes can be challenging, as every day is different. Even with the best intentions, people will miss the mark and have high or low blood glucose at times.

Common causes of low blood glucose for people living with diabetes include:

• Exercise

• Diabetes medications, like insulin, or oral medications that increase insulin production, such as sulfonylureas or glinides

• Illness

• Skipped meals

• Alcohol

With non-diabetic hypoglycemia, the most common cause of low blood sugar is medication (more on this below).

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Symptoms

Hypoglycemia symptoms can range from mild to severe, and they can feel different for each person. While some have obvious symptoms that have an easy fix, others may have “hypoglycemia unawareness.” This means that a person can miss early warning signs, which can lead to more severe symptoms.

People usually notice symptoms of hypoglycemia when their blood glucose is below 70 mg/dl. That’s because your body and brain need a higher level to properly work.

If you have hypoglycemia, you may notice:

• Hunger

• Fast heartbeat

• Shakiness

• Anxiety

• Sweating

• Tingling

• Dizziness

• Weakness

• Drowsiness

• Confusion

For most people, a mildly low blood sugar can be a nuisance. But a severely low blood sugar is a medical emergency. If you don’t get treatment for hypoglycemia, it can get worse and lead to seizures, coma, and even death.

Experts recommend that a person with diabetes spends under 4% of their time with a blood sugar level under 70 mg/dl. And they should spend under 1% of their time under 54 mg/dl. Since it’s very hard to know your exact level by symptoms alone, a continuous glucose monitor (CGM) is helpful to figure out these patterns.

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Diagnosis

Healthcare providers diagnose hypoglycemia when a blood glucose test shows a blood glucose that’s less than 70 mg/dl. 

If you have diabetes, you can check for hypoglycemia on your own with your glucometer. If you’re having hypoglycemia frequently, check in with your care team. They can help to make necessary changes to your treatment plan.

If you don’t have diabetes but think you’re having symptoms of hypoglycemia, you should visit a healthcare provider for an evaluation. They’ll do a physical exam, ask about your symptoms, and order testing if needed. 

They will want to know whether the symptoms of hypoglycemia improve when you have a sugary drink or meal high in carbohydrates.

There are two common tests providers use to check for low blood glucose:

1. Fasting blood glucose test

2. Mixed-meal tolerance test

You do both tests first thing in the morning to make sure you haven’t had anything to eat or drink. With a mixed-meal tolerance test, the provider gives you a sugary drink shortly before the blood glucose test. 

Treatments

It’s important to know the signs of hypoglycemia and how to treat them quickly, especially if you have diabetes. Regardless of the cause, a fast-acting carbohydrate can usually treat low blood sugar. It also helps to avoid foods with fiber and fat, as they slow down the absorption of sugar.

Fast-acting sugar sources (15 grams of carbohydrates) that you can carry with you at all times include:

• 4 glucose tablets

• 1 tube of glucose gel

• ½ cup of fruit juice or regular soda

• 6 large jelly beans

• 1 tablespoon of sugar or honey

The “15-15 rule” is an easy way to remember how to quickly treat a low blood sugar level that’s

between 55 to 69 mg/dl: 

• Take 15 grams of fast-acting carbohydrates (check out the list above)

• Wait 15 minutes

• Check your sugar level again — if you’re still below 70 mg/dl, repeat the cycle

Glucose below 55 mg/dl is more serious and may mean you need help. Teach others to call 911 if you:

• Don’t respond to fast-acting sugars

• Can’t eat or drink

• Have confusion or trouble talking or walking

• Pass out or have a seizure

If your provider prescribes glucagon — an emergency medication that you can inhale or inject to raise blood sugars — be sure your helpers know where it is and how to use it. Having a treatment plan for hypoglycemia is the best way to avoid emergency situations.

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Living

While hypoglycemia is a fact of life for people living with diabetes (especially T1D), there are steps you can take to stay safe: 

• Reach out to your care team with questions or concerns.

• Wear a medical alert bracelet.

• Explain your health condition to others and let them know when to call 911.

• Carry emergency supplies, such as a glucometer, fast-acting glucose, and glucagon (if you have a prescription).

You’ll need help from others if you can’t swallow, pass out, or have a seizure. That’s why it’s important to teach others around you about hypoglycemia. They’ll need to know when to call 911 and how to give glucagon (if available and necessary).

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Prevention

One of the best ways to avoid low glucose is through awareness. The only way to know for sure that you have hypoglycemia is to check with a glucometer or to wear a CGM for alerts about glucose changes. A CGM can be especially helpful while you’re sleeping. 

If you notice patterns with hypoglycemia, it’s important to let your care team know. They’ll look at the whole picture and make suggestions on the timing and amounts of medications, exercise, and foods.

There are also automated insulin delivery (AID) systems. They can help reduce the risk of severe hypoglycemia. This newer technology connects an insulin pump with a CGM and adjusts insulin in response to glucose levels. Ask your provider if a CGM or AID system may be a good fit for you. 

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