What is hypoglycemia?

Throughout the day, your blood glucose (also called blood sugar) will fluctuate within a certain range depending on various factors. This fluctuation is normal. What is not normal is having the blood sugar fluctuate out of the normal range, either below it or above it.

Hypoglycemia, or low blood sugar, occurs when your blood sugar drops below 70 mg/dL. When it gets below this threshold, it is important to increase the blood sugars quickly to prevent potentially life-threatening consequences such as seizure, coma and death. Hypoglycemia can occur in both type 1 and 2 diabetes.

What causes low blood sugar?

There are multiple factors that cause your blood sugar to be too low, including:

  • Taking too much insulin
  • Not eating enough carbs for how much insulin you are taking
  • Missing meals
  • Taking some medications
    • Sulfonylureas: glimepiride, glipizide, glyburide
    • Thiazolidinediones (such as pioglitazone and rosiglitazone) when used with sulfonylureas
    • SGLT2 inhibitors (such as empagliflozin, dapagliflozin, and canagliflozin) when used with sulfonylureas
  • The timing and amount of physical activity (for example, having a high-intensity exercise in the morning before eating breakfast)
  • Excessive alcohol consumption
What are the symptoms of low blood sugar?

If the blood sugar is too low, you may experience some of the following symptoms:

  • Shakiness
  • Sweating
  • Hunger
  • Nausea
  • Pale skin
  • Weakness or fatigue
  • Irritability or anxiety
  • Irregular or fast heartbeat
  • Dizziness and lightheadedness

If the blood sugar continues to drop to dangerously low levels, you may experience some of the following symptoms:

  • Confusion and/or unusual behavior
  • Blurry vision
  • Loss of coordination
  • Loss of consciousness

If you are taking a beta-blocker (metoprolol, atenolol, propranolol, etc.), some of these symptoms of hypoglycemia may be masked, such as hunger, shakiness, and irritability. However, one symptom that is not masked by beta-blockers is sweating.

What to do if you are experiencing low blood sugar?

When you experience symptoms of hypoglycemia or find that your blood sugars are between 55-69 mg/dL, the important thing is to know how to respond to it and increase your blood sugar quickly. The good thing is that hypoglycemia can be treatable at home without having to go see a doctor or go to the emergency department!

It is treatable at home using the method called the ‘15-15 rule’: have 15 grams of fast-acting carbs then check your blood sugar after 15 minutes. If your blood sugar is still low, then have another 15 grams of fast-acting carbs. After getting your blood sugar higher than 70 mg/dL, have a meal or a snack to prevent hypoglycemia from happening again.

Some options that contain 15 grams of fast-acting carbs include:

  • 4 ounces (½ cup) of juice or regular soda (not sugar-free)
  • 6 to 8 hard candies and jellybeans (review food label for how much to eat to get 15 grams of carbs)
  • 3 to 4 glucose tablets
  • 1 tablespoon of sugar, honey, or corn syrup
When should you see your doctor?

Although hypoglycemia can be treated at home, there are some cases when you should see your doctor or seek medical attention.

  • If your blood sugar continues to stay low after doing the 15-15 rule
  • If you feel like you are about to faint/lose consciousness, call 911 or have someone around you call 911 for you
  • If your blood sugar is severely low (below 54 mg/dL), call 911 in addition to doing the 15-15 rule
  • If you have had multiple episodes of hypoglycemia
What can you do to prevent hypoglycemia?

Hypoglycemia is preventable and reversible. It is better to be proactive than reactive. Here are some tips to stay on top of your health and blood sugar control:

  • Be able to identify signs and symptoms of hypoglycemia and how to quickly respond to it (the 15-15 rule and/or calling 911)
  • Have people around you know what the symptoms of hypoglycemia are and how to quickly respond to it in case you are unable to treat yourself, including when to call 911
  • Check your blood sugar regularly and log your blood sugar levels
  • Avoid skipping meals
  • Plan physical activity, meals, and medications based on blood sugar
    • For example, if your blood sugar tends to be low in the morning, do not do any moderate-high intensity exercise or inject insulin before having breakfast
  • Have fast-acting carbs readily accessible in case a hypoglycemic episode occurs
  • Carry some items that contain 15 grams of fast-acting carbs with you when you go out in case hypoglycemia occurs
  • Know what medications you are taking. Read the information leaflet and instructions about your medications, and learn of their side effects
  • If you are experiencing a lot of fluctuation in your blood sugar (including low blood sugars), consider talking to your doctor about changing your medication doses and/or about continuous glucose monitoring (CGM)


Prepared by Cynthia Vo, PharmD Candidate 2023