What’s the difference between hypoglycemia and hyperglycemia?

• Hypoglycemia means low blood sugar and is usually defined as a blood sugar less than 70 mg/dL.
• Hyperglycemia means high blood sugar and is usually defined as blood sugar greater than 125 mg/dL in a person who has not eaten in the last eight hours or more than 180 mg/dL in someone who ate two hours ago.

Diabetes is a common cause of hyperglycemia, but not everyone who has hyperglycemia has diabetes. Hypoglycemia can occur as a side effect of taking insulin for diabetes, but other people may develop hypoglycemia, too.

Mild levels of hypoglycemia can be treated by eating something that contains carbohydrates. If not treated promptly, hypoglycemia can result in seizures or losing consciousness. If a person has lost consciousness because of low blood sugar and therefore cannot eat or drink, then a drug called glucagon can be given.

Hyperglycemia from undiagnosed diabetes can become life-threatening.

If you experience symptoms of either too high or too low blood sugar, seek medical evaluation.

Related questions

• What foods should I eat or avoid for hypoglycemia?
• Can you have hypoglycemia without diabetes?
• Does metformin cause hypoglycemia?

How your body balances glucose

Glucose is a major source of energy for your body. The level of glucose in your blood will go up and down over the course of a day depending on when and what you have eaten and how much activity you are performing. A healthy human body regulates the amount of glucose in the blood within a range of values considered normal.

Your pancreas and liver are both involved in maintaining this balance. Under normal circumstances, when you eat, your pancreas releases the hormone insulin, which helps your body use the energy created from the food you eat. If your body doesn't need the energy right away, it can store it as glycogen in the liver. When your body needs energy, signaled by a decrease in blood sugar, your pancreas releases glucagon. The presence of glucagon tells your liver to release the stored glycogen so that your body can use it for energy.