Encephalopathy due to diabetes and its influence on driving

Diabetes mellitus is the most common endocrine disorder, since those suffering it are more than three million in Spain.

Diabetes mellitus is associated with the risk of diabetic ketoacidosis (DKA), non-ketotic hyperglycemic hyperosmolar coma (NKHHC), and with a group of late complications including retinopathy, nephropathy, peripheral and coronary atherosclerotic arteriopathy, and neuropathies of the autonomous nervous and peripheral system.

Diabetic ketoacidosis (DKA)

In patients with insulin-dependent diabetes mellitus (IDDM), DKA can be triggered by missing the insulin treatment, or by an acute infection, injury, or infarction, responsible for the regular treatment with insulin to be insufficient.

The increased liver synthesis of ketone bodies induces metabolic acidosis and respiratory compensation. The acetone accumulating in plasma is an anesthetic for the CNS, and is eliminated slowly through breathing.

The initial symptoms include polyuria, nausea, vomiting and sometimes abdominal pain. Usually, signs of dehydration are seen with hypotension and hypokalemia.

Somnolence is a frequent later manifestation, that if the patient is not treated, progresses to coma.

Advice on diabetic ketoacidosis (DKA)

In general, patients with well treated IDDM, when they recognize the symptoms, inject themselves a quantity of insulin and seek rapidly medical care.
It is important to notify our diabetic drivers, that if this situation appears while driving, they must immediately the car in a safe area and ask for assistance.
Even if they self-inject insulin and feel better, they must not drive to the medical center as soon as possible. This clinical situation can progress with an adequate control to a loss of consciousness.
Diabetic patients who have suffered an episode of DKA require close medical monitoring, as frequent clinical and laboratory assessments are required on the outcome of DKA and the corresponding adjustments of treatment.
Hypotension and coma influence negatively the prognosis, and can leave neurological sequels.
The medical expert will inform the patient of his evolution, advising him against driving until the cause leading to DKA is controlled, as well as the adjustment of diabetes.
The neurological sequels caused in some case by acute cerebral edema that has responded to treatment are disabling for driving.
It would be advisable that the physician reported in writing in each review of the existing neurological injuries and their outcome, to be able to assess the ability of the patient to drive and advise him with this regard.

Non-ketotic hyperglycemic hyperosmolar coma (NKHHC)

It is a syndrome characterized by a disorder in the consciousness level, that is sometimes associated with focal convulsive or generalized crises, severe dehydration and hyperglycemia, not associated with ketoacidosis.

It is a complication of non-insulin-dependent diabetes mellitus (NIDDM) undiagnosed previously or poorly controlled, with a very high mortality.

It frequently occurs after a period of symptomatic hyperglycemia, where fluid intake is insufficient to prevent the severe dehydration caused by the osmotic diuresis induced by hyperglycemia.

The most frequent triggering factors are infections or the administration of drugs that impair tolerance to glucose or increase fluid loss, such as glucocorticoids, phenytoin, immunosuppressives and diuretics.

The clinical manifestations are CNS disorders, dehydration, mild metabolic acidosis, and prerenal uremia.

The consciousness level ranges from dulling to coma, and at times, transient hemiplegia occurs.

The treatment is urgent and at hospital.

Advice on non-ketotic hyperosmolar hyperglycemic coma (NKHHC)

After the recovery from an acute episode of NKHHC, careful control with insulin adjusted to diet requires a more or less prolonged period when the patient cannot drive.
The expert physician will report on the adequate adjustment of the diabetic patient, that will enable him to drive safely and without startling due to hyper or hypoglycemia.
Medicine advances always provide the adequate control and treatment of patients, permitting them to keep their ability to drive in most cases, always adopting the recommended precautions for their safety.

General recommendations to the diabetic driver

Any diabetic patient should be advised by his physician with regard to diabetes and driving, from being the “patient” to be the “agent” of his own health.
Diabetes mellitus associated with severe metabolic instability and requiring hospitalization, prevents from driving.
During travels, he should be accompanied by people who know his disease and know how to help him if complications arise. He should stop every hour for resting.
In general patients with well treated IDDM, when they recognize the symptoms of DKA, inject themselves a quantity of insulin and seek rapidly medical care.
It is important to inform that if this situation appears while driving, he must stop immediately the car avoiding risks and ask for assistance.
Even if they self-inject the insulin and feel better they should not drive to reach the medical center as soon as possible, since this clinical situation can progress without an appropriate control to a loss of consciousness.
The medical expert will inform the patient of his evolution, advising him against driving until the cause that led to DKA is controlled, as well as the adjustment of the treatment for diabetes.
It would be advisable that the physician reported in writing in each review, of the possible neurological sequels and their outcome, to be able to assess the ability of the patient to drive and advise him with this regard.
After the recovery of an acute episode of NKHHC, the strict control with insulin following diet, requires a more or less prolonged period when he cannot drive. The physician will report on the adequate adjustment, that will permit him to drive safely and without startling for hyper or hypoglycemia.
The driver should take in a visible place inside the car the medical report of specifying his disease and the treatment, so that in the event of an accident he can be identified and adequately managed.
No driver can drink alcohol if it is going to drive. In the case of the diabetic drivers they are recommended never to drink alcohol, for the possible interference with their medication, and accordingly the increased risk when driving.
All these warnings will make the diabetic driver a wiser driver due to his deep knowledge of his disease, with a lower risk of suffering episodes of diabetic encephalopathy, and possibly a lower rate of accidents than the other drivers since he will be more aware of the risks of driving.