According to the Joslin Diabetes Center, hypoglycemia, or low blood sugar, is one of the most common problems associated with insulin treatment, but it can also affect people who take pills for diabetes. Hypoglycemia can occur suddenly. In most cases, it's mild and can be successfully treated by eating or drinking a small amount of glucose-rich food.

What is hypoglycemia?

When you have diabetes, your target blood glucose level is between 70 to 130 milligrams per deciliter (mg/dL) before meals, and below 180 mg/dL after you start to eat a meal. Hypoglycemia is when your blood glucose level is below 70 mg/dL.

When blood glucose levels begin to fall, your pancreas pumps out another hormone, glucagon, which signals the liver to break down glycogen and release glucose into the bloodstream so your blood glucose starts to return to normal.

This glucagon response to hypoglycemia is impaired in some people with diabetes, and other hormones such as adrenaline, or epinephrine, may increase blood glucose levels, explains the National Institute of Diabetes and Digestive Disorders and Kidney Disease (NIDDK). But, when you treat your diabetes with insulin or pills to increase insulin production, glucose levels cannot easily return to the normal range.

Causes of Hypoglycemia in Diabetes

Some causes of hypoglycemia in diabetes include:

  • Alcoholic beverages.
  • Meals or snacks that are too small, delayed, or skipped.
  • Too much physical activity.
  • Diabetes medications such as insulin, pills that increase insulin production such as chlorpropamide (Diabinese®) and glimepiride (Amaryl®), and injectable drugs such as Pramlintide (Symlin).
  • Certain combination pills such as glipizide and metformin (Metaglip®).
  • Taking pills such as rosiglitazone (Avandia®) in conjunction with insulin and other diabetes pills.

Also, intensive insulin therapy (IIT) may give you a threefold increased risk of hypoglycemia.

Symptoms of Hypoglycemia

Warning signs of low blood sugar can be physical, emotional, or mental, states the Joslin Diabetes Center. These symptoms of hypoglycemia also vary from person to person and may change over time:

  • anxiety
  • confusion
  • difficulty speaking
  • dizziness or light-headedness
  • hunger
  • nervousness
  • shakiness
  • sleepiness
  • sweating
  • weakness

During sleep, hypoglycemia may cause:

  • crying out or nightmares
  • fatigue, irritability or confusion on waking up
  • perspiration

Dangers of Hypoglycemia in Diabetes

Low blood sugar affects brain and motor function, and symptoms such as dizziness, fainting, sleepiness and weakness can increase your risk of accidents and injury, for instance when you're driving or operating machinery.

Repeated episodes of hypoglycemia may impair your body's ability to recognize the warning signs and respond appropriately (hypoglycemia unawareness), which is part of a syndrome called hypoglycemia associated autonomic failure (HAAF). Severe low blood sugar may cause seizures, and in the worst case scenario, it can be fatal.

How to Prevent Hypoglycemia

  • Understand how and when to take your medications. Your doctor may recommend you switch your medications to match changes in your routine.

  • Beware the symptoms. Learn to recognize your body's response to low blood sugar levels and act quickly and appropriately.

  • Test frequently. Monitor your blood glucose levels frequently, especially before driving or doing a dangerous activity such as skiing, or operating heavy machinery. 

  • Improve your diet. Work with your diabetes specialist or dietitian to design the best meal plan for you. Eat regular meals, the right portions, and don't skip meals or snacks.

  • Eat at the right times. According to the ADA, insulin has peak times when it works the hardest, so plan your meals and snacks around those periods.

  • Choose the best snacks. Elizabeth Staum, a nutrition educator at the Joslin Diabetes Center recommends low- or no-carb snacks such as rolled-up cold cuts of turkey or chicken, a granola bar, or one medium fruit.

  • Monitor blood glucose closely around physical activity. Check it before you begin, during and afterwards. Have a snack if the level is below 100 mg/dL.

  • Get advice if you're on intensive insulin therapy. Because of the increased risk of hypoglycemia from this treatment, speak to your specialist about how to avoid it.

  • Ask about diabetes medications. Find out from your doctor if a prescribed drug increases your risk of hypoglycemia, and whether you need to adjust the dosage before exercise, or if you skip a meal.