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Diabetics With Low Blood Sugar at Risk for Driving Accidents

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WebMD Health News

Feb. 25, 2000 (Atlanta) -- Diabetics with even mildly low blood sugar -- hypoglycemia -- can find their driving performance seriously impaired, leading to more missed stop signs, inappropriate braking, fast driving, and sudden-stop crashes, according to a small study in Diabetes Care.

What's more, when drivers don't take immediate corrective action -- drinking a soda or pulling off the road -- brain activity changes may prevent their ever taking any corrective action, leading to a stuporous state that can cause serious accidents, the study shows.

"There were individual differences, of course, but as a group [diabetic patients in the study] drove worse when they were mildly hypoglycemic than when [blood sugars were normal]. But the [impaired judgment it caused] was most interesting and quite distressing," lead author Daniel J. Cox, PhD, of the Behavioral Medicine Center at University of Virginia Health System in Charlottesville, tells WebMD.

Chronic low blood sugar causes brain function and judgment to become temporarily impaired. "We had patients telling us, 'I knew I was going hypoglycemic, I knew I needed to treat myself. I had a sandwich right next to me but I couldn't make myself take it, I couldn't make myself eat it,'" Cox says. "That's why it's so critical to treat yourself right away. Don't wait till you get to the office to treat yourself. Do it immediately."

Using a sophisticated driving simulator (developed with help from NASA flight simulator engineers), Cox's team was able to document that driving impairments occur at relatively mild degrees of hypoglycemia (blood glucose levels in the 60s).

The study involved 37 adults with type 1 diabetes and an average age 35 -- all of whom had been taking insulin for at least two years. During the 30-minute driving test, each was given insulin intravenously to progressively lower blood glucose levels.

During the first hour, each volunteer drove the simulator for 30 minutes while blood sugar levels were normal; during the second 30-minute test, blood sugar levels were decreased to hypoglycemic levels. Patients were unaware that their blood glucose levels were being altered. Driving performance, brain activity, and corrective behaviors were continually monitored -- every five minutes -- as were blood glucose levels, perception of symptoms, and impaired judgment.

Every five minutes during the 30-minute tests, volunteers were asked to rate their symptoms, their driving ability, and their need to treat themselves (a soft drink was in the glove compartment). "They were continually being reminded," says Cox. "They were instructed that any time they couldn't drive, they should pull over and treat themselves. Yet only one-third of our volunteers both recognized their driving impairments and took corrective action."

During hypoglycemia, there was more driving off the road, more speeding, and brakes were used more often on the open road, says Cox. Fourteen volunteers (38%) demonstrated extreme impairments in their driving while hypoglycemic. For example, during the last 15 minutes of driving, volunteers failed to stop at stop signs significantly more often and were involved in more crashes at sudden stops.

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If the level is below 70 or you are experiencing symptoms such as shaking, sweating or difficulty thinking, you will need to raise the number immediately. A quick solution is to eat a few pieces of hard candy or 1 tablespoon of sugar or honey. Recheck your numbers again in 15 minutes to see if the number has gone up. If not, repeat the steps above or call your doctor.

People who experience hypoglycemia several times in a week should call their health care provider. It's important to monitor your levels each day so you can make sure your numbers are within the range. If you are pregnant always consult with your health care provider.

Congratulations on taking steps to manage your health.

However, it's important to continue to track your numbers so that you can make lifestyle changes if needed. If you are pregnant always consult with your physician.

Your level is high if this reading was taken before eating. Aim for 70-130 before meals and less than 180 two hours after meals.

Even if your number is high, it's not too late for you to take control of your health and lower your blood sugar.

One of the first steps is to monitor your levels each day. If you are pregnant always consult with your physician.

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