Recently, the NYT (Tuesday, January 29, 2012, p D5) had a very interesting and important article in the Science Times section. The article was entitled: “Driving with diabetes,” and was written by Laura Geggel. As the title of the article suggests, the subject was all about the hazards that people with diabetes encounter when driving motor vehicles. The article was very well researched and is worth reading, not only for people with diabetes, but also for their family members, friends, and colleagues. Basically, people with diabetes who take insulin or other drugs such as sulfonylureas which can cause hypoglycemia (low blood sugar), need to take special precautions to minimize the risks, particularly with driving (the author also pointed out other diabetes-and-driving risks such as nerve damage and poor vision, both common diabetes complications. There are considerable data to show that people with diabetes have many more motor vehicle accidents than people without diabetes, although the vast majority of most motor vehicle accidents do not involve people with diabetes. But, does the increased risk for people with diabetes mean that they should not drive? In my opinon, there is no good reason people why with diabetes who take insulin or other drugs that can cause hypoglycemia should not be able to drive motor vehicles and participate in other potentially hazardous activities (e.g., washing windows at the Empire State Building, scuba diving, mountain climbing), as long as they know how to minimize the risks. People who take insulin are prohibited from obtaining commercial driving licenses for interstate driving. In-state commercial driving, including operating construction equipment is regulated by each state and fairly recently, many states have determined that it is safe for people who take insulin to drive trucks and such in-state if certain precautions are taken. Nationally, the Federal Aviation Administration (FAA) does not allow people who take insulin to be commercial pilots but they may obtain private pilot licenses, again if they follow very specific precautions (e.g., maintain a specified level of blood sugar control, check blood sugars regularly during flights). In my view, these are reasonable approaches to deal with the risks.
Can people with diabetes who take insulin and other drugs that cause hypoglycmia prevent hypoglycemia?
It is a fact of life that people with diabetes, particularly those who take insulin injections or use an insulin pump, will inevitably have occasional hypoglycemia, particularly if they are striving to have well-controlled diabetes. Many studies have shown that the better the diabetes is controlled, the greater the risks for hypoglycemia. This is not very surprising. If a person maintains their blood sugar at a high level most of the time, they are at much lower risk for hypoglycemia than a person whose blood sugar level is frequently in or close to the normal range. One of the best demonstrations of this came from the Diabetes Control and Complications Trial, or DCCT, the study that proved the relationship between blood glucose control and risks for the development of diabetes complications. In previous entries, I have discussed the DCCT in detail (you will need to dig deep into the archives). Basically, two groups of patients with type 1 diabetes (insulin-dependent diabetes) were treated with either an intensive insulin regimen or a standard regimen; at the time the study starte in 1983, a standard regimen was 1-2 insulin injections/day while an intensive regimen was at least 4 insulin injections/day or use of an insulin pump. The study plan was to achieve blood glucose levels as close to normal as possible in the intensive tretment group. In the standard treatment group, there were no specific blood glucose goals. The intensive treatment group was quite successful in maintaining near-normal blood glucose levels throughout the 9-year study while the standard treatment group blood glucose levels were, on average much higher. Although the intensive treatment group developed many fewer diabetes complications of the eyes, nerves, and kidneys, they also had a 3-fold increase in the frequency of serious episodes of hypoglycemia, including motor vehicle accidents.
Lessons learned about hypoglycemia from the DCCT
I was one of the DCCT investigators, and during the course of the DCCT. I, the other the investigators, and the study volunteers learned quite a bit about hypoglycemia during the course of the study. By the end of the study, the frequency of serious episodes of hypoglycemia was markedly reduced even though the intensive treatment group maintained near-normal blood glucose levels. What did we learn? First of all, we learned that there is no substitute for frequent blood glucose monitoring. All study subjects in the intensive treatment group were urged to check fingestick blood glucose levels at least 4 times daily, and also before exercise, before driving or undertaking any potentially dangerous activity (e.g., using a riding lawn mower, chain saw, etc.). In addition study volunteers were urged to always carrry a rapidly-acting form of glucose with them (such as glucose tablets) and wear a diabetes identification tag. Volunteers were also urged to check their blood sugar level once a week at 3 AM, to monitor for asymptomatic nocturnal hypoglycemia. Finally, they were urged to consider changes in their treatment regimen after all episodes of hypoglycemia unless the causes were known and could be prevented in the future. We as investigators, reminded the volunteers about these hypoglycemia precautions at every clinic visit.
We now know that the hypoglycemia precautions employed during the DCCT work and are, perhaps, even more important for diabetes patients now since the standard treatment for all patients with diabetes is to maintain blood sugar levels as close to the normal range as possible. One cannot remove all risks for hypoglycemia in a patient who takes insulin or other medications that can cause hypoglycemia, but one can markedly decrease the risks without compromising control of the diabetes. Fear of hypoglycemia is not a good reason to have poor control of the diabetes. But, all physicians who care for patients with diabetes must be certain their patients understand the seriousness of hypoglycemia and how to minimize their risks. The message needs to be reinforced frequently. Following publication of the NYT article, there was a nice “letter to the editor,” published February 4, 2013 with some interesting and useful comments. You might want to check that out as well as the article.
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