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What is Hypoglycemia?

Hypoglycemia is the medical term for low blood glucose. It can be dangerous for people with diabetes. You need to know what to watch for, and what to do to correct it.

The symptoms of low blood glucose, or hypoglycemia, include shakiness, headache, and sudden moodiness. But some people with diabetes don’t notice any symptoms when their blood glucose levels are low. This is called hypoglycemic unawareness. Hypoglycemic unawareness can happen for several reasons:

  • Over time, poorly controlled high blood glucose can cause damage to the hormonal system that tells you when your blood glucose is low.
  • People who have low blood glucose often may get used to the feelings that come with it. They may no longer understand that those feelings are a warning sign of low blood glucose.
  • Some medications may mask the symptoms of low blood glucose (for example, sleeping pills, sedatives, or heart medicines called beta blockers).

When to See a Doctor

Call your provider for advice or an appointment if:

  • You can’t control your hypoglycemia, in spite of taking action to correct it.
  • You have two to three readings in a row with results of 70 mg/dL or less.
  • You have more than two unexplained episodes of hypoglycemia in a week.
  • You have repeated low glucose readings during a particular time of day.
  • Get emergency care if you feel you are about to pass out.


There are a lot of reasons why your blood glucose might drop too low. Here are a few common causes:

  • Not eating on your regular schedule or going long periods between meals can cause your blood glucose to drop.
  • Medications to control diabetes can also cause hypoglycemia, especially if they’re not taken as prescribed. For example, too much insulin can sometimes cause low blood glucose, which is why it’s sometimes called an “insulin reaction.” Taking your diabetes medication at the wrong time can also make your blood glucose drop too low.
  • Being more active than usual can cause hypoglycemia, since active muscles use up more glucose than inactive muscles. So even though exercise is a great way to keep your blood glucose levels normal, you need to exercise sensibly to stay safe.

To prevent hypoglycemia, stick to your self management plan. If you’re having regular episodes of hypoglycemia and you can’t figure out why — talk to your care team. They will help you figure out the problem and show you how to correct it.

Diagnosis and Tests

Providers often rely on three key benchmarks to diagnose hypoglycemia:

  1. Presence of symptoms or signs
  2. Low blood glucose levels, confirmed by a blood test
  3. Absence of symptoms following return to normal blood sugar levels


Hypoglycemia usually comes on quickly. So if you suspect you’re hypoglycemic, check your blood glucose. If that’s not possible, go ahead and treat yourself as if your blood glucose is low:

  • Tell someone around you that you have low blood glucose, if you can. You might need someone to help you, and they might not know what’s going on with you unless you tell them.
  • Eat or drink 15 grams of fast-acting, low-fat carbohydrate. Give this treatment about 15 minutes to work. Don't continue to eat until your symptoms go away. Overeating may have a rebound effect, causing your blood glucose to go too high.
  • Check your blood glucose 15 minutes after you eat. If it’s still below 70, eat another 15 grams of carbohydrate. Repeat this until your blood glucose is over 70 or until your symptoms go away.
  • Once your blood glucose is back to normal, get back on your management plan and look for causes. Do you need to do a better job of following your meal plan, or taking your medications as prescribed? If you can’t identify a cause of your hypoglycemia, contact your healthcare provider. You might need a change in your plan.


Although you hope to avoid low blood glucose, you still need to be prepared in case it does happen to you. Always do the following:

  • Make sure that the people you spend the most time with (coworkers, family, teachers, and friends) know the signs of low blood glucose. Show them how they can help you if you aren’t able to help yourself.
  • Always carry a carbohydrate snack and your emergency glucagon kit (if you have one).
  • Carry a card in your wallet explaining that you have diabetes and what someone can do to help you if you show signs of hypoglycemia.
  • Wear a diabetes ID.


Along with checking your blood glucose, watch out for the following symptoms of low blood glucose:

  • Shakiness or dizziness
  • Sweating
  • Hunger
  • Headache
  • Pale skin color
  • Sudden moodiness or behavior changes, such as nervousness, irritability, or crying for no apparent reason
  • Clumsy or jerky movements
  • Difficulty paying attention, or confusion
  • Tingling sensations around the mouth
  • Fainting or seizure