Dan Fried, a 47-year-old videographer who has Type 1 diabetes, never made it to the diner to meet his brother. As he drove through New Jersey that night in November 2010, he said his blood sugar fell and he became disoriented. He pulled his van to the side of the road, where state troopers, who had received a call about an erratic driver, found him slumped behind the wheel, barely coherent.
Believing Fried to be intoxicated and seemingly uncooperative, the troopers tried to frisk and handcuff him. In the scuffle, his wrist was broken. He was wearing a bracelet that identified him as a diabetic.
“I was very upset at the whole thing,” he said in an interview. Fried filed a lawsuit alleging civil-rights violations. The state attorney general declined comment on pending litigation.
Sudden bouts of low blood sugar, or hypoglycemia, can lead to confusion, delayed reaction, visual disturbances or loss of consciousness. Even in the absence of low blood sugar, people with diabetes may have impaired vision or nerve function in the feet, which can affect driving.
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Partly as a result, drivers with diabetes are 12 to 19 percent more likely than other drivers to have a car accident, studies show.
A study of 202 people with diabetes who were taking insulin found that about 60 percent of participants never tested their blood-glucose levels before driving. Most participants said they would stop driving if they began to feel symptoms of hypoglycemia, but it can be difficult to recognize milder symptoms, such as blurry vision, sweating or feeling tired or irritable, said Dr. Daniel Lorber, director of endocrinology at New York Hospital Queens.
“If it drops further, then you get into some severe thinking and judgment issues, and that’s what we’re concerned about,” he said. “You could pass out or have a seizure.”
Awareness of the problem is surprisingly limited. A study in 2003 that surveyed people with diabetes in seven U.S. and four European cities found that half of those with Type 1 and three-fourths of those with Type 2 diabetes reported that their doctors had never told them about the dangers of hypoglycemia and driving.
While most accidents related to diabetes complications happen to a small group of people with Type 1 diabetes, who need to take insulin, people with Type 2 diabetes are also at risk.
An analysis of American insurance claims, published in November in the journal Diabetes, Obesity and Metabolism, focused on people with Type 2 diabetes who were taking a diabetes drug other than insulin. It found that drivers under age 65 who had been treated for hypoglycemia were 40 percent more likely to have had a motor-vehicle accident than those who had not had hypoglycemic episodes.
“Up until now, most people assumed that diabetes-related driving accidents were caused by insulin therapy,” said Dr. Brian Frier at the University of Edinburgh and an author of the study. They didn’t think people on other therapies would cause an accident through hypoglycemia, he said.
Frier noted that a class of diabetes drugs called sulfonylureas, which stimulate the pancreas to release insulin, may be especially likely to trigger hypoglycemia, particularly longer-acting sulfonylureas like the drug glyburide. Shorter-acting drugs in this class, including glipizide and gliclazide, may be safer for drivers with diabetes, he said.
Drivers at risk for hypoglycemia also “have a responsibility to make sure that their blood-glucose level is not too low,” said Dr. Ned Kennedy of the Cleveland Clinic. He advised drivers with low blood sugar to eat something sugary, wait 15 minutes and check again.
“Just taking the time to do that could save them a lot of trouble and prevent them from being a danger to themselves or to other people” on the road, he said.
Daniel Cox, at the University of Virginia Health System, and his colleagues have developed a program called Blood Glucose Awareness Training, which teaches people to recognize the signs of low blood sugar.
Cox also is enrolling patients in Diabetes Driving, a study that aims to identify and prevent other risks associated with drivers who have diabetes.
The vast majority of accidents have nothing to do with diabetes, however, and Cox and other experts are wary of stigmatizing people with the disease. “We don’t want to isolate out diabetics as bad drivers,” he said.