Hypoglycemia (Low Blood Sugar)

Hypoglycemia happens when your blood sugar (glucose) drops below a range that’s healthy for you. It’s also called low blood sugar or low blood glucose. It’s most common in people with diabetes, especially if you take insulin. It can also sometimes happen to people without diabetes.

For most people with diabetes, hypoglycemia is when your blood sugar level is below 70 milligrams per deciliter (mg/dL) or 3.9 millimoles per liter (mmol/L). For most people without diabetes, this is when your blood sugar level is below 55 mg/dL or 3.1 mmol/L.

Glucose is your body’s main source of energy. If your blood glucose drops too low, your cells and brain don’t get the energy they need to work. This leads to symptoms like shakiness and confusion. It requires immediate treatment by eating or drinking sugar/carbohydrates. Severe hypoglycemia can be life-threatening.

Too much insulin or diabetes medication, not eating enough and too much physical activity are the main causes of low blood sugar if you have diabetes. If you don’t have diabetes, certain medications, alcohol use or health conditions may lead to it.

Symptoms of low blood sugar

Symptoms of hypoglycemia often start when your blood sugar is around 70 mg/dL or lower if you have diabetes. If your blood sugar drops quickly, symptoms may begin before it reaches this number. Low blood sugar can happen quickly and can vary from person to person and with each episode.

Many of the early symptoms of low blood sugar happen because your body releases hormones that help raise your blood sugar. These signs are your body’s way of warning you that you need to take action. The signs include:

• Shaking or trembling
• Sweating and chills
• Faster heart rate
• Dizziness or lightheadedness
• Extreme hunger
• Weakness
• Confusion or trouble concentrating
• Anxiety or irritability
• Color draining from your skin

If your blood glucose is often high, your body can get used to it. Because of that, you may feel symptoms of low blood sugar at higher levels.

Signs of severe hypoglycemia include:

• Blurred or double vision
• Slurred speech
• Clumsiness or difficulty with coordination
• Being disoriented
• Seizures
• Loss of consciousness

This is life-threatening. Severe hypoglycemia needs immediate treatment with emergency glucagon and/or medical intervention.

You can also have low blood sugar while sleeping (nocturnal hypoglycemia). Symptoms may include restless sleep, sweating through your pajamas or sheets and having nightmares.

Hypoglycemia causes

Low blood sugar happens for different reasons based on whether you have diabetes or not.

Causes if you have diabetes

Common situations that can lead to low blood glucose levels include:

• Taking too much insulin, the wrong insulin or injecting it into muscle instead of fat tissue
• Not timing insulin and carb intake correctly (for example, waiting too long to eat a meal after taking insulin for it)
• Taking too much or too high a dose of oral diabetes medications
• Being more active than usual
• Drinking alcohol without eating
• Eating meals later than usual or skipping meals

If you’re pregnant and have Type 1 diabetes, you’re also more likely to have low blood sugar during the first trimester due to hormone changes.

Causes in people without diabetes

The two main types of non-diabetes-related hypoglycemia are reactive hypoglycemia and fasting hypoglycemia.

Reactive hypoglycemia

Reactive hypoglycemia (or postprandial hypoglycemia) happens when your blood sugar is low after a meal. It typically happens two to four hours after eating.

Researchers don’t know the exact cause. But they think it happens due to a sudden spike and then a fall in blood sugar after eating certain simple carbohydrates like potatoes, white bread, cake and pastries.

Bariatric surgery can also cause reactive hypoglycemia. This is because sugar can move through your body too quickly, causing your body to release too much insulin.

Fasting hypoglycemia

For most people without diabetes, not eating for a long time (fasting) doesn’t lead to hypoglycemia. This is because your body can keep blood sugar in a healthy range.

But certain conditions and situations can lead to fasting hypoglycemia, including:

• Excessive alcohol consumption: Alcohol can stop your liver from making new glucose. If you drink a lot of alcohol over several days and don’t eat enough food, your body can use up its stored sugar.
• Critical illness: End-stage liver disease, sepsis, starvation or kidney failure cause your body to use a lot of energy.
• Adrenal insufficiency: Adrenal insufficiency causes low cortisol levels. Cortisol helps keep your blood sugar in a normal range. When cortisol levels are too low, your blood sugar can drop.
• Non-islet cell tumor hypoglycemia (NICTH): This is a rare but serious condition where a tumor releases too much of a hormone that acts like insulin.
• Insulinoma: This is a rare tumor in your pancreas that makes insulin. It leads to hypoglycemic episodes, most commonly in the early morning.

If you think you have hypoglycemia, talk to a healthcare provider.

Hypoglycemia unawareness

Some people don’t have early symptoms or don’t notice them. This is called hypoglycemia unawareness. It can increase the risk of severe episodes and sudden loss of consciousness.

How doctors diagnose this condition

If you have diabetes, checking your blood glucose level can confirm low blood sugar.

If you don’t have diabetes but have hypoglycemia symptoms, your healthcare provider may check your blood sugar during a supervised fast. You may need other tests, like imaging tests, to look for an underlying cause.

If your provider suspects reactive hypoglycemia, they may recommend a mixed-meal tolerance test (MMTT). During this test, you’ll drink a beverage containing protein, fat and sugar. A provider checks your blood sugar several times over the next few hours to see how your body responds.

How is hypoglycemia treated?

You treat mild to moderate hypoglycemia by eating or drinking sugar (carbohydrates).

Healthcare providers often recommend the “15-15 rule” to manage low blood sugar:

• Eat or drink 15 grams of fast-acting carbs to raise your blood glucose.
• After 15 minutes, check your glucose level.
• If it’s still below 70 mg/dL, have another 15 grams of fast-acting carbs.
• Repeat until your glucose is at least 70 mg/dL.

Children may need fewer grams of carbs to treat hypoglycemia. Check with your child’s healthcare provider to see what’s right for them.

How is severe hypoglycemia treated?

Severe hypoglycemic episodes require the use of emergency glucagon. Usually, someone else has to give it to you. It comes as an injection or nasal powder. It triggers your liver to release stored glucose, which then raises blood sugar.

If someone you know needs emergency glucagon, follow the instructions on the package. When the person regains consciousness (usually in five to 15 minutes), they may have nausea and vomiting. If they’re lying down, roll them onto their side to prevent choking. If they have slurred speech or are disoriented or unconscious, don’t give them food or liquid. They could choke.

You should call 911 or emergency services right away for help. Even if they have taken glucagon, they still could need emergency services.

Complications

Frequent mild to moderate hypoglycemia can affect your daily activities, including work and school. Operating heavy equipment, such as driving a vehicle, while having low blood glucose levels can also be dangerous. You may be more likely to get in an accident.

Prolonged severe hypoglycemia is life-threatening and can lead to:

• Multiple organ failure
• Cardiac arrhythmias
• Cardiac arrest
• Permanent brain damage
• Coma or death

What can I expect if I have hypoglycemic episodes?

Frequent low blood sugar episodes can be dangerous if you have diabetes. It may mean your treatment plan needs to be adjusted. Talk with your healthcare provider if you have frequent lows.

Hypoglycemia can make it hard to think clearly and can become dangerous if it happens while you’re sleeping, driving or alone.

Here are some tips to help you stay safe:

• Always have snacks available in your home and on you when you’re away from home.
• Wear a medical alert necklace or bracelet that says you have diabetes.
• Teach people you spend time with about hypoglycemia and how they can help you.
• Always have emergency glucagon on hand. Educate your loved ones on how and when to use it.

How can I prevent this condition?

It can be difficult to totally prevent low blood sugar when you have diabetes. But your healthcare provider may be able to adjust your diabetes management plan to try to reduce the number of low blood glucose episodes you have.

It’s easiest to do this when you and your healthcare provider understand what causes your blood sugar to drop. Give your healthcare provider as much information as possible about any low blood sugar episodes. Fixing the problem may be as simple as changing the times you take medication, eat and exercise.