Medical Indications for Revoking a Driver's License
Medical conditions that impair a driver's ability to exercise safe control over a motor vehicle warrant license revocation, with the decision based on concrete evidence of actual driving risk rather than diagnosis alone.
Key Principles for License Revocation
The fundamental approach to license revocation should focus on functional impairment that creates established safety risk, not merely the presence of a medical diagnosis 1. Licensing decisions must reflect deference to the professional judgment of the evaluating physician while balancing public safety 1.
Specific Medical Indications
Diabetes-Related Conditions
Recurrent severe hypoglycemia (≥2 episodes per year) may indicate inability to safely operate a motor vehicle 1. However, critical distinctions apply:
- Loss of consciousness due to hypoglycemia within the past 12 months warrants evaluation 1
- Hypoglycemia requiring intervention from another person or that interfered with driving requires assessment 1
- Hypoglycemia without warning symptoms poses significant risk 1
- Severe hypoglycemia during sleep alone should not disqualify a person from driving 1
- Single episodes explained by medication changes, illness, or pregnancy may warrant waivers rather than revocation 1
Prior hypoglycemia-related driving mishaps exponentially increase future risk: two episodes of severe hypoglycemia in 12 months increases risk to 12%, while two collisions in 2 years increases risk by 40% 1.
Diabetes Complications Affecting Driving
- Loss of visual acuity or peripheral vision 1
- Loss of sensation in the right foot (may require vehicle modifications rather than revocation) 1
- Obstructive sleep apnea with daytime somnolence (more common in type 2 diabetes) 1
Neurological Conditions
Epilepsy and seizure disorders represent major indications for license restriction 2, 3:
- Following an epileptic seizure, drivers may not drive for 6 months 3
- Multiple seizures extend the restriction to one year after the last seizure 3
Cerebrovascular events 3:
- Cerebral infarction or hemorrhage: unfit to drive for at least 6 months 3
- After 6 months, fitness depends on functional disorders and driving test results 3
- Transient ischemic attack (TIA) does not necessarily affect fitness to drive 3
Other neurological conditions 2, 3:
- Intracranial tumors (assessed based on functional disorders; may receive time-limited licenses) 3
- Progressive neurological disorders requiring medical assessment 3
- Dementia/cognitive impairment (most common condition in voluntary reporting systems, representing 45% of cases) 4
- Conditions affecting cognition, vision, reaction speed, motor coordination, peripheral sensation, or visuospatial processing 2
Cardiovascular Conditions
Coronary artery disease may increase crash risk, particularly when associated with sudden incapacitating events 5.
Syncope requires medical assessment and potentially driving evaluation 3.
Evaluation Process
Risk Assessment Questionnaire
A short questionnaire should identify high-risk drivers by asking about 1:
- Loss of consciousness in past 12 months
- Episodes requiring intervention from others
- Episodes developing without warning
- Visual impairment
- Loss of sensation in right foot
- Daytime somnolence
Important Caveats
Do not use HbA1c alone to determine driving risk, as episodic hypoglycemia (not average glucose control) increases crash risk 1.
Avoid "one strike" approaches to licensing—contributory factors that may mitigate risk must be considered 1.
Individual assessment is mandatory—the mere fact that a condition has come to the licensing agency's attention should not predetermine the decision 1.
Physician Reporting Considerations
Physicians should exercise professional judgment rather than being subject to mandatory reporting requirements 1. Mandatory reporting has unintended consequences:
- Discourages frank discussion between patients and physicians 1
- No evidence that mandatory reporting reduces crash rates or improves public safety 1
- Under mandatory reporting systems, only 72% of currently driving patients would inform their physician of breakthrough seizures (versus 96% under patient reporting) 6
Reports should focus on whether the driver's mental or physical condition impairs safe vehicle control, not solely on diagnosis 1.
License Reinstatement
Drivers with suspended licenses should be eligible for reinstatement after a sufficient period (usually no more than 6 months) upon physician advice that appropriate adjustments have been made 1. Periodic follow-up evaluation is necessary after reinstatement 1.
Evidence of Crash Risk
Drivers reported as medically impaired show significantly elevated crash rates: 9.3% versus 2.2% for controls (fourfold difference), with crash involvement decreasing rapidly after reporting and license action 4. People with diabetes overall have a 12-19% increased crash risk compared to the general population 1.