Several studies have demonstrated how hypoglycaemia affects cognitive function and mood. Neuroglycopenia interferes with every cognitive domain to varying degrees, but as blood glucose falls, complex mental tasks are progressively disrupted. One everyday activity that involves complex cognitive processes is driving. Vital cognitive functions that are essential for driving, such as attention, reaction time, and hand-eye coordination, are impaired by hypoglycaemia. Hypoglycaemia while driving is a potential problem in people treated with insulin, and while this risk is carefully assessed in many countries with restrictions imposed where necessary, in many parts of the world there are few or no regulations regarding diabetes and driving.
How common are hypoglycaemia-related driving incidents? In a study in the USA by Cox and colleagues1, more than half of the drivers with insulin-treated diabetes had experienced at least one driving mishap over the preceding year that could be attributed to hypoglycaemia.
The absence of regulations governing driving and diabetes in many parts of the world may give the impression in these countries that driving a vehicle while receiving treatment with insulin poses few problems, but this is a serious misconception, hence the importance of informing drivers with insulin-treated diabetes everywhere about measures to ensure safe driving.
It is the responsibility of the individual to manage their diabetes and try to avoid hypoglycaemia while driving. While early non-severe hypoglycaemia may not induce symptoms, it can still adversely affect the driver’s cognitive function. One study showed that only one in three drivers self-treated a low blood glucose in this situation, and fewer than 25% of drivers realised that their driving was impaired.2 The following precautions should be followed when driving:
Different national and international approaches are illustrated by the following examples.7
In Europe, driving licences are classified as group 1 licences (for cars) and group 2 licences (for trucks/lorries and other large vehicles). Generally, group 1 licence holders must inform their national driving authority if they experience multiple severe hypoglycaemia events (and their licence may be revoked until such a problem has been addressed and resolved appropriately). Insulin-treated drivers can apply for a group 2 licence but must fulfil more stringent requirements, including provision of a record of regular blood glucose test results and reporting of severe hypoglycaemia episodes.3
In the United States, 23 states require a person to have a medical evaluation before being issued a driver’s licence if they have diabetes or altered perception.5
People with diabetes who take blood glucose-lowering medications, including insulin, must legally advise the Driver Licensing Authority. Commercial drivers in Australia must be assessed by a diabetes specialist to receive a report on their fitness to drive. Current guidelines advise starting driving only when glucose is >90 mg/dL.8 Depending on their medical fitness to drive, special conditions may be placed on drivers’ licences.9
Despite the prevalence of diabetes in the Gulf Cooperation Council (GCC) countries being among the highest in the world, none of the GCC countries have yet enacted legislation to regulate driving with diabetes.10,11
From a global perspective, many countries have few or no regulations or restrictions for people with medical conditions, such as insulin-treated diabetes, that could affect driving performance. This is a serious problem for road safety and is reflected by a higher number of road accidents related to diabetes in these countries. Nonetheless, the absence of national regulatory involvement should not deter individual drivers with insulin-treated diabetes from taking careful precautions when driving to protect themselves and other road users.
The increasing use of continuous glucose monitoring (CGM) and flash glucose monitoring in western countries by people with insulin-treated diabetes should help to identify (and hopefully avoid) hypoglycaemia while driving, especially if alarms are used. Technological advances in monitoring glucose may help alert drivers to a falling glucose concentration, perhaps by having the driver’s glucose profile displayed on the vehicle’s instrument panel.
There may be serious legal consequences of a failure to take appropriate care of diabetes while driving. If hypoglycaemia is the principal cause of a road traffic accident, the driver is not absolved of responsibility because of their medical condition. In many cases, the driver has been considered at fault for allowing their glucose level to fall into the hypoglycaemic range, resulting in revocation of their motor insurance cover and the risk of incurring substantial financial and legal penalties.
It is important that drivers who experience hypoglycaemia while driving are aware of the risks that this can cause and take the necessary precautions to drive safely and prevent road mishaps.
- Cox DJ, Ford D, Gonder-Frederick L, et al. Driving mishaps among individuals with type 1 diabetes: a prospective study. Diabetes Care. 2009;32(12):2177-2180. doi:10.2337/dc08-1510
- Inkster B, Frier BM. Diabetes and driving. Diabetes Obes Metab. 2013;15(9):775-783. doi:10.1111/dom.12071
- Graveling AJ, Frier BM. Driving and diabetes: problems, licensing restrictions and recommendations for safe driving. Clin Diabetes Endocrinol. 2015;1(1):8. doi:10.1186/s40842-015-0007-3
- Graveling AJ, Warren RE, Frier BM. Hypoglycaemia and driving in people with insulin-treated diabetes: adherence to recommendations for avoidance. Diabet Med J Br Diabet Assoc. 2004;21(9):1014-1019. doi:10.1111/j.1464-5491.2004.01288.x
- American Diabetes Association, Lorber D, Anderson J, et al. Diabetes and driving. Diabetes Care. 2014;37 Suppl 1:S97-103. doi:10.2337/dc14-S097
- Ahmed AA. Hypoglycemia and safe driving. Ann Saudi Med. 2010;30(6):464-467. doi:10.4103/0256-4947.72268
- Beshyah SA, Beshyah AS, Yaghi S, Beshyah WS, Frier BM. A global survey of licensing restrictions for drivers with diabetes. Br J Diabetes. 2017;17(1):3. doi:10.15277/bjd.2017.117
- rawley S, Stephens AN, McAuley SA, et al. Driving with Type 1 Diabetes: Real-World Evidence to Support Starting Glucose Level and Frequency of Monitoring During Journeys. Diabetes Technol Ther. 2022;24(5):350-356. doi:10.1089/dia.2021.0460
- National Diabetes Service Scheme. Diabetes and Driving. Published online 2020.
- Batais MA, Alamri AK, Alghammass MA, et al. Diabetes and driving recommendations among healthcare providers in Saudi Arabia. Saudi Med J. 2018;39(4):386-394. doi:10.15537/smj.2018.4.22179
- Hassoun AAK, Abdella N, Arouj MA, et al. Driving and diabetes mellitus in the Gulf Cooperation Council countries: Call for action. Diabetes Res Clin Pract. 2015;110(1):91-94. doi:10.1016/j.diabres.2015.08.002