Driving and insulin--consensus, conflict or confusion?

Hypoglycemia While Driving in Insulin-Treated Patients: Incidence and Risk Factors

OBJECTIVES

This study aimed to investigate a potential daily-life concern for patients with diabetes hypoglycemia while driving by (1) estimating their incidence in insulin-treated drivers, (2) determining factors associated with their occurrence, and (3) analyzing patients' behavior regarding prevention of hypoglycemia.

METHODS

We conducted an observational study from November 2013 to May 2018 in the endocrinology-diabetology-nutrition department of our university hospital. All patients treated for diabetes older than 18 years admitted in the department were eligible. A specific questionnaire assessing attitudes, knowledge, and consequences of hypoglycemia was provided. In this study, only insulin-treated patients who regularly drive were analyzed.

RESULTS

On the 233 insulin-treated drivers included, 45 (19%) self-reported at least 1 hypoglycemia while driving in the preceding year. Two factors were significantly associated with their occurrence: type 1 diabetes (odds ratio [OR] = 3.19; 95% confidence interval [CI] = 1.55-6.57) and experiences of asymptomatic hypoglycemia (OR = 2.20; 95% CI = 1.05-4.63). Awareness of the treatment hypoglycemia risk because of information provided by a medical specialist was also but nonsignificantly associated with hypoglycemia while driving (OR = 2.61; 95% CI = 0.86-7.92). Forty-one patients (18%) combined those 3 variables, 20 (49%) of them self-reported hypoglycemia while driving. Thirty-four percent of the patients never carried carbohydrates for hypoglycemia correction. Seventy-six percent do not monitor blood glucose level before driving.

CONCLUSIONS

Our questionnaire allowed us to highlight that 19% our cohort of insulin-treated drivers declared experiencing hypoglycemia while driving. Risk factors identified and prevention data collected should help us better target patient education.

Driving with diabetes in the future: in-vehicle medical monitoring

The motor car is a ubiquitous feature of modern life, and most of us spend significant amounts of time in a car, behind the wheel. Driving a vehicle requires complex coordination of cognitive, motor, and sensory skills. All of these aspects can be affected adversely by diabetes per se, with hypoglycemia being the main concern for people with diabetes who drive. Here we introduce the concept of using the motor vehicle as a device to collect and deliver physiological and clinical information, which, in turn, may enable more people to drive more safely by reducing the chances of medical mishaps behind the wheel. This is particularly relevant for people living with diabetes who are at risk from a number of medical conditions that have the potential to have an impact on safe driving. The development of in-vehicle medical monitoring presents a new opportunity for novel collaborations between two industries, which have safety as a core value.

Motor vehicle crashes in diabetic patients with tight glycemic control: a population-based case control analysis

BACKGROUND

Complications from diabetes mellitus can compromise a driver's ability to safely operate a motor vehicle, yet little is known about whether euglycemia predicts normal driving risks among adults with diabetes. We studied the association between glycosylated hemoglobin (HbA1c) and the risk of a motor vehicle crash using a population-based case control analysis.

METHODS AND FINDINGS

We identified consecutive drivers reported to vehicle licensing authorities between January 1, 2005 to January 1, 2007 who had a diagnosis of diabetes mellitus and a HbA1c documented. The risk of a crash was calculated taking into account potential confounders including blood glucose monitoring, complications, and treatments. A total of 57 patients were involved in a crash and 738 were not involved in a crash. The mean HbA1c was lower for those in a crash than controls (7.4% versus 7.9%, unpaired t-test, p = 0.019), equal to a 26% increase in the relative risk of a crash for each 1% reduction in HbA1c (odds ratio = 1.26, 95% confidence interval 1.03-1.54). The trend was evident across the range of HbA1c values and persisted after adjustment for measured confounders (odds ratio = 1.25, 95% confidence interval 1.02-1.55). The two other significant risk factors for a crash were a history of severe hypoglycemia requiring outside assistance (odds ratio = 4.07, 95% confidence interval 2.35-7.04) and later age at diabetes diagnosis (odds ratio per decade = 1.29, 95% confidence interval 1.07-1.57).

CONCLUSIONS

In this selected population, tighter glycemic control, as measured by the HbA1c, is associated with an increased risk of a motor vehicle crash.

The decision not to drive during hypoglycemia in patients with type 1 and type 2 diabetes according to hypoglycemia awareness

OBJECTIVE

In recent years, there has been an ongoing discussion on the relationship between diabetes and driving. As driving performance will inevitably decline at lower levels of glycemia, patients' decisions concerning driving or taking corrective action when hypoglycemia occurs immediately before or during driving seems paramount.

RESEARCH DESIGN AND METHODS

Twenty-four type 1 diabetic patients with normal awareness of hypoglycemia (T1Norm group), 21 type 1 diabetic patients with impaired awareness of hypoglycemia (T1Imp group), and 20 type 2 diabetic patients with normal awareness of hypoglycemia (T2 group) were studied. They were asked whether they felt hypoglycemic and whether they would currently drive during experimental euglycemia (5.0 mmol/l) and hypoglycemia (2.7 mmol/l).

RESULTS

In the T1Norm group, 1 patient (4.2%) decided to drive during hypoglycemia. In the T1Imp group, 9 patients (42.9%) said they would drive in the hypoglycemic condition. In the T2 group, 5 patients (25%) would drive. This was more frequently the case for patients on oral hypoglycemic agents (chi2 = 4.44; P = 0.04). No effect of sex (chi2 = 0.78; P = 0.38) or age (chi2 = 0.22; P = 0.64) was noted.

CONCLUSIONS

Patients with type 1 diabetes and impaired awareness of hypoglycemia frequently decided to drive while hypoglycemic, whereas patients with type 1 diabetes and normal awareness of hypoglycemia appeared to make safe decisions concerning hypoglycemia and driving. Strikingly, patients with type 2 diabetes and normal hypoglycemia awareness frequently made potentially dangerous decisions as well, particularly when using oral hypoglycemic agents. Therefore, early, clear, and consistent education is imperative.

Diabetes and driving mishaps: frequency and correlations from a multinational survey

OBJECTIVE

The intensive treatment of diabetes to achieve strict glycemic control is a common clinical goal, but it is associated with an increased incidence of hypoglycemia. Becoming hypoglycemic while driving is a hazardous condition and may lead to a greater incidence of driving mishaps. This study investigated whether diabetes is associated with increased risk of driving mishaps and correlates of such a relationship.

RESEARCH DESIGN AND METHODS

During routine visits to diabetes specialty clinics in seven U.S. and four European cities, consecutive adults with type 1 diabetes, type 2 diabetes, and nondiabetic spouse control subjects (n = 341, 332, and 363, respectively) completed an anonymous questionnaire concerning diabetes and driving.

RESULTS

Type 1 diabetic drivers reported significantly more crashes, moving violations, episodes of hypoglycemic stupor, required assistance, and mild hypoglycemia while driving as compared with type 2 diabetic drivers or spouse control subjects (P < 0.01-0.001). Type 2 diabetic drivers had driving mishap rates similar to nondiabetic spouses, and the use of insulin or oral agents for treatment had no effect on the occurrence of driving mishaps. Crashes among type 1 diabetic drivers were associated with more frequent episodes of hypoglycemic stupor while driving, less frequent blood glucose monitoring before driving, and the use of insulin injection therapy as compared with pump therapy. One-half of the type 1 diabetic drivers and three-quarters of the type 2 diabetic drivers had never discussed hypoglycemia and driving with their physicians.

CONCLUSIONS

Type 1 diabetic drivers are at increased risk for driving mishaps, but type 2 diabetic drivers, even on insulin, appear not to be at a higher risk than nondiabetic individuals. Clinical and treatment factors appear to increase risk, e.g., more frequent hypoglycemia while driving, method of insulin delivery, and infrequent self-testing before driving. Physicians are encouraged to talk to their type 1 diabetic patients about hypoglycemia and driving.

The metabolic demands of driving for drivers with type 1 diabetes mellitus

BACKGROUND

The active cognitive-motor demands of driving may have a significant metabolic demand that could contribute to the development of hypoglycemia. Conversely, symptoms caused by the stress of driving may be confused with hypoglycemia and lead to false alarms. This study examined the metabolic demand and the physiological stress of driving on type 1 diabetes mellitus (T1DM) drivers.

METHODS

Forty-three T1DM drivers were placed on a constant insulin infusion/variable dextrose infusion to maintain euglycemia for 30 min while either watching a driving video or actually driving a simulator, in a counterbalanced crossover design. Dextrose infusion, heart rate, epinephrine, and subjective symptom ratings were measured every 5 min. Additionally, subjects were monitored for self-treatment (drinking soda).

RESULTS

While blood glucose (BG) levels were equivalent across both conditions, actual driving was associated with a higher dextrose infusion rate (p = 0.02), more autonomic symptoms (p < 0.05), increased heart rate (p < 0.001), a trend (p = 0.09) for greater epinephrine release, and more frequent hypoglycemic self-treatment (p < 0.001).

CONCLUSIONS

Driving is a task with a significant metabolic demand, which may lower BG, and also that driving stress may be associated with symptoms similar to those of hypoglycemia. Physicians should discuss with their T1DM patients hypoglycemia and driving, and encourage measuring blood glucose before driving and during long drives.

Insulin-treated diabetes and driving in the UK

Diabetes, and particularly insulin-treated diabetes, has important implications for motor vehicle driving, largely because of its association with potential hypoglycaemia. For this reason, most countries operate some driving restrictions on insulin-treated diabetic patients, as well as systems of intermittent reassessment of hypoglycaemic risk. In the UK, regulations are operated by the Driver and Vehicle Licensing Agency (DVLA), which is an agency of the Department of the Environment, Transport and the Regions (DETR). They are supported by an Expert Panel which advises the Secretary of State on diabetes-related issues relating to fitness to drive. The patient organization Diabetes UK is also concerned with diabetes and driving issues, largely from a position of lobbying policy-influencers and supporting individual cases. All parties involved with diabetes and driving issues recognize the need for more research on the subject, as the current literature is flawed in design, though no convincing excess of accidents amongst diabetic drivers has been conclusively demonstrated. Currently in the UK, Class 2 vehicles (large trucks and passenger vehicles) are barred to diabetic drivers on insulin. European law has recently extended this to so-called C1 (large vans and small lorries) and D1 (minibuses) vehicles, though the law has recently been revised to allow individual consideration for potential diabetic C1 drivers on insulin treatment. Diabetes and insulin-treated diabetes is an emotive and difficult issue, for which a stronger evidence base is urgently needed.

Self-treatment of hypoglycemia while driving

OBJECTIVE

While it is clear that progressive diabetic hypoglycemia leads to neuroglycopenia, which impairs driving, it is not clear what contributes to patients' detection and subsequent self-correction of hypoglycemia/driving impairments. Drivers with Type 1 Diabetes Mellitus (T1DM) who did and did not engage in self-treatment during experimental hypoglycemia driving are compared physiologically and psychologically.

METHOD

38 drivers with T1DM drove a sophisticated driving simulator during euglycemia and progressive hypoglycemia. Subjects were continually monitored for driving performance, EEG activity and whether they self-treated with a glucose drink. Every 5 min measures were taken of blood glucose (BG) and epinephrine levels, perceived neurogenic and neuroglycopenic symptoms and driving ability. For the four weeks prior to this hospital study, subjects participated in a field study. Using a hand-held computer just prior to routine self-measurements of BG, subjects rated neurogenic and neuroglycopenic symptoms and made judgements about BG level and ability to drive as they did in the hospital.

RESULTS

Drivers who did and did not self-treat did not differ in terms of their pre-hospital exposure to hypoglycemia, their depth and rate of BG fall during experimental testing, or their epinephrine response to hypoglycemia. Subjects who self-treated detected more neurogenic and neuroglycopenic symptoms than those who did not self-treat. They also experienced less EEG defined neuroglycopenia during the progressive hypoglycemic drive as compared to those who did not self-treat. Perceived need to self-treat and EEG parameters correctly classified 88% of those who did treat from those who did not self-treat. Further, subjects who self-treated were more aware of hypoglycemia and when not to drive while hypoglycemic in the field study.

CONCLUSION

There is a narrow window between a patient's detection of hypoglycemic symptoms and the need to self-treat, and neuroglycopenia, which impairs self-treatment. Consequently, drivers with T1DM should be vigilant for signs of hypoglycemia and driving impairment (e.g. trembling, uncoordination, visual difficulties) and encouraged to treat themselves immediately when they suspect hypoglycemia while driving.