Symptoms and Signs of Hypoglycemia
(Low Blood Sugar)

Medical Author:
Medically Reviewed on 9/3/2021

Doctor's Notes on Hypoglycemia
(Low Blood Sugar)

Hypoglycemia is a medical problem when the concentration of glucose in the blood is below 60 mg/dL. The concentrations can affect brain function (levels below 50 mg/dL) and/or can lead to coma or even death at very low levels of glucose in the blood. Common symptoms and signs of hypoglycemia include trembling, clammy skin, heart palpitations, anxiety, sweating, hunger, and/or irritability. These symptoms can be quickly relieved in most individuals when blood glucose levels are higher than 60 mg/dL. This is accomplished by the patient eating or drinking a highly concentrated glucose-containing substance (like sugared lemonade or a piece of hard candy) or by IV glucose-containing fluid. This rapid alteration of symptoms after the administration of glucose is also a sign of hypoglycemia. However, when the glucose level approaches severely low levels where the brain is derived of glucose, signs and symptoms become progressively worse (for example, severe headaches, confusion, and/or loss of the ability to think, seizures, coma, and even death).

There are many common causes of hypoglycemia. Most individuals who develop symptoms and signs of hypoglycemia have diabetes that results in loss or inadequate production of insulin. Other common causes include

  • overmedication with insulin,
  • missed meals,
  • alcohol use,
  • use of medications such as beta blockers and other drugs,
  • severe infections,
  • cancers causing poor fluid and/or food intake,
  • adrenal insufficiency,
  • kidney failure,
  • liver failure,
  • genetic defects,
  • insulin-producing tumors and other problems.

Very low glucose levels are considered by most physicians to be a medical emergency.

What Is the Treatment for Hypoglycemia (Low Blood Sugar)?

Hypoglycemia is treated by giving the patient glucose. Oral doses (like the sugar present in a glass of fruit juice or hard candy) are rapidly absorbed and may quickly resolve many instances of mild to moderate hypoglycemia. Patients with severe hypoglycemia can be given IV glucose preparations. Underlying problems should be addressed to decrease or prevent this potentially life-threatening illness from happening again.

Must Read Articles:


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.