Skip to main content

What’s the difference between hypoglycemia and hyperglycemia?

Medically reviewed by Sally Chao, MD. Last updated on Sep 27, 2023.

Official answer

  • 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.

Hypoglycemia Hyperglycemia
Definition Blood sugar less than 70 mg/dL Fasting blood sugar of more than 125 mg/dL or more than 180 mg/dL two hours after eating
Symptoms Feeling jittery, tired or dizzy
Being hungry, irritable or confused
Having a headache
Slurring your words
Extreme thirst
Dry mouth
Frequent urination
Blurry vision
Shortness of breath
Causes Skipping meals or fasting
Too much insulin
Binge drinking alcohol

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

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.

  1. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Hypoglycemia. July 2021. Available at: [Accessed September 20, 2021].
  2. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Managing Diabetes. December 2016. Available at: [Accessed September 20, 2021].
  3. Hantzidiamantis PJ, Lappin SL. Physiology, Glucose. StatPearls. 2021 Jan.

Read next

Related medical questions

Related support groups