Hypoglycemia Unawareness

Author: Judy Kohn, RN, BSN, CDE

Last Updated: Saturday, October 20, 2007

Q: "I never feel myself going low until I'm there so I need to remember to take a snack before I exercise. Why don't I get a warning? I used to but don't anymore and I'm insulin resistant too."

A: You are describing a condition called hypoglycemia unawareness, which basically means that you are unaware your glucose is low because you don’t recognize any warning signs, and so you are unable to take action to correct it. This condition has been described for many years as being an irreversible problem; only recently there have been reports that sometimes this condition can be reversed.

How would you know if you had hypoglycemia unawareness?

Below is a list of questions describing hypoglycemia unawareness. If you answer yes to any of the questions listed below, we recommend that you discuss this situation with your physician.

1. Have you often obtained blood glucose readings below 55 mg/dL without any of the usual symptoms of hypoglycemia (sweating, tremors, rapid heartbeat, nervousness, extreme hunger)?
2. Have you had episodes of impaired thinking?
3. Have others observed you in situations where you appeared pale, tired, confused, or acting as if in “slow motion?”
4. Have you acted irritable or forgetful, even though you physically felt fine?
5. Have you had difficulty managing a hypoglycemic episode, which required the assistance of others?
6. Have you ever had a seizure or loss of consciousness without any warning signs?
7. Do you try to maintain very tightly controlled blood sugars (often running below 90 mg/dL)?
8. Have you had frequent episodes of hypoglycemia?
9. Have you had diabetes over 20 years?
10. Have you had a recent episode of severe hypoglycemia?

What causes hypoglycemia unawareness?

There are several issues involved, so let me first explain how the body is supposed to respond to low blood glucose--by releasing two counter regulatory hormones called epinephrine and glucagon:

• When blood glucose drops, your autonomic nervous system releases epinephrine (also called adrenaline). Epinephrine has two main roles: it tells the liver to produce glucose and supply your brain with needed fuel; also it is responsible for many of the signals that would tell you that your glucose is getting low—such as: sweating, heart pounding, trembling or shaking, and tingling in the hands or feet.
• Along with epinephrine, a hormone called glucagon is released from your pancreas which does exactly the opposite of insulin: glucagon stimulates your liver to release stored glucose to help supply your body with the much needed glucose. In other words, both of these counter regulatory hormones attempt to get your body back to normal.

What goes wrong?

• Decreased glucagon response: Although the cause is still not certain, it is known that many people with type 1 diabetes lose their glucagon response to hypoglycemia within the first 5-10 years of the disease
• Decreased epinephrine response: Later in the course of diabetes, some people with type 1 diabetes also lose their epinephrine response. This is more common in people who have autonomic neuropathy (nerve damage).
• Recent episode of low blood glucose: Studies now show that just one bad episode of low blood glucose can temporarily reduce both your hormone and symptom response to hypoglycemia, creating a vicious cycle of recurrent hypoglycemia without symptoms. It’s as if you have become temporarily numb to feeling symptoms of low glucose.
• Altered glucose threshold: It has now been shown that when you run too low (for example if you were aiming for very tight control), your ability to recognize low glucose might change, and rather than feeling low at 80 mg/dL, for example, you might not sense that you’re low until you are 50 mg/dL or lower. Think of this as if you reset your heater thermostat at home to not “kick in” until the temperature dropped below 40 degrees, rather than having it at the usual setting to maintain a comfortable room temperature of 72 degrees.

Conditions that put you at risk for hypoglycemia unawareness

• Diabetes present for many years—although it is most often associated with type 1 diabetes, hypoglycemia unawareness can also be present in those with type 2 diabetes
• Intensive therapy, aiming for very good diabetes control
• Autonomic neuropathy
• Experiencing frequent low blood glucose levels
• Pregnancy with diabetes (and aiming for very tight control)
• Certain age groups: children under 10 and the elderly
• Decreased kidney function (the body is not able to clear out the insulin or oral agents as efficiently)
• Use of beta-blocking blood pressure medications
• Alcohol use (masks the symptoms of hypoglycemia and interferes with the action of counter regulatory hormones)

How to prevent, possibly reverse, and/or safely manage hypoglycemia unawareness:

• Sometimes this condition can be reversed by avoiding hypoglycemia—this may mean that you would need to change your target glucose levels. Be sure to discuss this with your healthcare team.
• Reassess your diabetes regimen—if you are on insulin, many people do better with frequent small doses of insulin, or use of an insulin pump, rather than the more traditional 2-shots per day.
• Be careful with alcohol intake—never drink on an empty stomach, and drink moderately.
• Inform your family, friends and co-workers of your condition, and explain to them the possible subtle signs that may indicate you are getting low(impaired thinking, acting in slow motion, appearing pale and tired, acting irritable or confused).
• Always wear and carry medical identification.
• Monitor your blood glucose frequently, and always test your blood glucose before driving or any activity, as well as periodically in the middle of the night. You may also consider using a continuous glucose monitoring system. Confirm with your healthcare team what is considered a safe glucose level for you to perform any activity. Many experts recommend that people with hypoglycemia unawareness never be below 100 mg/dL.
• Plan ahead and take extra precaution before activity (such as by lowering your diabetes medication and or taking an extra snack).
• Remember that when your glucose is changing rapidly, there may be a difference in the glucose readings between your finger and other test sites, like the forearm, upper arm, thigh, calf, and other areas of the hand. Because blood flow to the fingers is 3-5 times faster than other alternate sites, blood samples from the finger may show changes in your glucose sooner than the forearm, upper arm, thigh, calf, and other parts of the hand. The possible difference in glucose readings between the finger and other alternate sites could delay your detection of hypoglycemia.
• If you are using an Abbott Diabetes Care meter, when testing for hypoglycemia or if you have hypoglycemia unawareness, we recommend testing on the finger only.
• If you are using any other meter, you should review your Owner’s Manual for instructions on when and where to test if you think you are low or have hypoglycemia unawareness.

Finally, be sure to discuss all of this with your healthcare team.

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Related Links

Joslin Diabetes Center
http://www.joslin.org

DOC09391-Rev-B 11/07