Hypoglycemia can mean danger behind the wheel

Many drive when they know they are impaired

Do you warn your patients not to drive in an impaired state? It’s not a matter of drinking and driving. Recent research shows a surprisingly large percentage of patients with diabetes are probably getting behind the wheel when they are impaired by low blood sugar. And some are consciously making the decision to drive even when they know they are dangerous on the road.

Recent research from the University of Virginia shows patients need counseling about checking their blood sugars before they get into the driver’s seat. "We don’t think of talking to patients about driving and hypoglycemia because it seems so obvious," says lead researcher William L. Clarke, MD, professor of pediatrics at the University of Virginia Health Sciences Center in Charlottesville.

But Clarke and his colleagues were stunned to find that as many as 45% of Type 1 diabetics are putting themselves and others at risk by driving because they are unaware they are hypoglycemic. Others are getting behind the wheel even when they recognize they have low blood sugar.

"I don’t know which is more frightening," says Clarke.

He says patients cite circumstances in which they feel they have no choice except to drive, even though they may be jeopardizing their own lives, their passengers, and other motorists. "They’ll say they had to pick up the kids or they had no other way to get home from work or they had some pressing work obligation. [Other excuses include] they got out of football practice late after school or even that they had no glucose tablets or other way to bring up their sugars," Clarke says. "It’s analogous to driving after a few drinks. Most of us have done that at one time or another without thinking of the possible serious consequences."

Shocking discovery

Sanford Mallin, MD, an endocrinologist in private practice in Milwaukee, says the study shocked him as well because Clarke’s results will very likely translate to Type 2 diabetics and their far greater numbers on the road, although Type 2s have a lower risk of severe hypoglycemia.

Clarke’s study was published in the Aug. 25 issue of the Journal of the American Medical Associ-ation. It has further significance because it measured the ability of Type 1 diabetics to recognize when they are hypoglycemic.

His 65 subjects were all Type 1 diabetics who drive and who routinely test at least twice daily. Each subject was given a hand-held computer to record data on symptoms, cognitive function, insulin dosage, food, activity, estimated and actual blood glucose levels, and what decision was made about driving.

Despite simulator tests that show blood sugars between 65 and 47 mg/dL lead to impaired driving ability, patients in the study said they would drive 40% to 45% of the time when they estimated their blood glucose was between 60 mg/ dL and 70 mg/dL.

Worse yet, 18% to 38% of the time, participants said they would drive even when their blood glucose levels were at a dangerously low level of below 40 mg/dL. When they actually tested their blood sugars and were certain the levels were in the 60 mg/dL to 70 mg/dL range, participants still chose to drive 60% of the time. And 38% to 47% chose to drive even when their blood glucose level was less than 40 mg/dL.

Clarke says as far as he knows, no one has done a study on the accident rates of diabetic drivers.

"If you talk to police, you find they don’t ask a person if he has diabetes," says Clarke. "Most states do not have a diabetes notation on drivers’ licenses, and a diabetic involved in an accident will not volunteer the information because he doesn’t want anyone to know he was driving impaired."

Getting away with living dangerously

Additionally, many diabetics have gotten behind the wheel in the past when they knew their sugars were low and conclude they have "gotten away with it before, so they can probably get away with it again," he explains.

Clarke concedes that poor judgment is symptomatic of hypoglycemia because poor cognitive function is one symptom of the condition. So, Clarke says, it stands to reason patients may not make the best decisions about such crucial issues. "I strongly encourage diabetes health care teams to discuss driving with their patients," he says.

Clarke recommends caregivers take these tactics:

- Ask patients how they determine if it is safe to drive.

- Recommend that they monitor their blood levels before driving.

- Advise them to plan their trips so they don’t miss meal times.

- Suggest they always have glucose tablets or other sources of sugar with them.

In addition, Clarke says, it is incumbent on health care teams to help diabetic patients better detect their blood sugar levels. "Help them recognize the symptoms, the moods associated with low blood sugar like drowsiness, irritability, and other mood changes," says Clarke. "Help them learn more about insulin and food peaks and keep diaries so they’ll recognize when they are low."

"It’s just not something we think about very often, but we must begin thinking along those lines and talking to patients about it now," says Mallin.

[Contact William Clarke at (804) 924-5897.]