Low blood sugar is a condition that occurs when the body's blood sugar (glucose) decreases and is too low.
Blood sugar below 70 mg/dL is considered low. Blood sugar at or below this level can be harmful.
The medical name of low blood sugar is hypoglycemia.
Hypoglycemia; Insulin shock; Insulin reaction
Insulin is a hormone made by the pancreas. Insulin is needed to move glucose into cells where it is used for energy. Without enough insulin, glucose builds up in the blood instead of going into the cells. This leads to symptoms of diabetes.
Low blood sugar occurs due to any of the following:
Your body's sugar (glucose) is used up too quickly
Glucose is released into the bloodstream too slowly
Too much insulin is released into the bloodstream
Low blood sugar is common in people with diabetes who are taking insulin or other medicines to control their diabetes.
Babies born to mothers with diabetes may have severe drops in blood sugar.
In people who do not have diabetes, low blood sugar may be caused by:
Insulinoma, which is a rare tumor in the pancreas that produces too much insulin
Lack of a hormone, such as cortisol, growth hormone, or thyroid hormone
Severe heart, kidney, or liver failure
Infection that affects the whole body
Some types of weight-loss surgery
Symptoms you may have when your blood sugar gets too low include:
Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.