Hypoglycemia: MedlinePlus Mobile Medical Encyclopedia

Hypoglycemia is a condition that occurs when your blood sugar (glucose) is too low.

Blood sugar below 70 mg/dL is considered low. Blood sugar at or below this level can harm you.

Causes
Hypoglycemia occurs when:

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

Insulin is a hormone that reduces blood sugar. It is produced by the pancreas in response to increased glucose levels in the blood.

Low blood sugar is most commonly seen in people with diabetes who are taking insulin or other medicines to control their diabetes.

Babies who are born to mothers with diabetes may have severe drops in blood sugar.

Hypoglycemia in people who do not have diabetes may be caused by:

Drinking alcohol
Insulinoma - a rare tumor in the pancreas that produces too much insulin
Lack (deficiency) of a hormone, such as cortisol or thyroid hormone
Severe heart, kidney, or liver failure or a body-wide infection
Some types of weight-loss surgery

Symptoms
Symptoms you may have when your blood sugar gets too low include:

Double vision or blurry vision
Fast or pounding heartbeat
Feeling cranky or acting aggressive
Feeling nervous
Headache
Hunger
Shaking or trembling
Sweating
Tingling or numbness of the skin
Tiredness or weakness
Trouble sleeping
Unclear thinking

Sometimes your blood sugar may be too low, even if you do not have symptoms. If your blood sugar gets too low, you may:

Faint
Have a seizure
Go into a coma

Exams and Tests
Home monitoring of blood sugar with a fingerstick sample will show readings lower than 70 mg/dL on your glucose monitor.

A blood glucose test in a blood sample taken from your veins will be low.

Treatment
Treatment depends on the cause. People with diabetes will need to learn how to treat and prevent low blood sugar levels.

If hypoglycemia is caused by an insulinoma (insulin-releasing tumor), surgery to remove the tumor is the best treatment.

Possible Complications
Severe hypoglycemia is a medical emergency that may cause seizures and permanent brain damage. Severe hypoglycemia in which you become unconscious is also called insulin shock.

When to Contact a Medical Professional
If signs of low blood sugar do not improve after you have eaten a snack that contains sugar:

GET A RIDE to the emergency room, or
Call a local emergency number (such as 911)

DO NOT drive when your blood sugar is low.

Get medical help right away for a person with diabetes or low blood sugar who:

Becomes less alert
Cannot be woken up

Alternative Names
Insulin shock; Low blood sugar

References
Cryer PE. Hypoglycemia. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Kronenberg: Williams Textbook of Endocrinology . 12th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 34.

Update Date: 6/27/2012
Shehzad Topiwala, MD, Chief Consultant Endocrinologist, Premier Medical Associates, The Villages, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.