Diabetes mellitus and driving

As with other systemic diseases, all the body is affected in diabetes mellitus and, therefore, its disorders can cause any sign or symptom, many of which hinder the ability to drive.

Diabetes mellitus is the most common endocrine disorder, as over three million Spaniards suffer it.

The diabetic patient, though well controlled, is a driver at risk for the possible complications of the disease and of the treatment. Accordingly, it is important that the physician recognizes the diabetic driver at risk and trains him to care for his disease.

Every diabetic patient should be advised by his physician with regard to diabetes and driving, changing from a “patient” to an “agent” of his own health.

All medical warnings will lead the diabetic driver to be a wiser driver due to his disease, and possibly with a lower accident rate than other drivers, for being more aware of the risks of driving.

The advances of medicine permit the control and adequate treatment of patients, enabling them to keep their ability to drive in most cases, always adopting the recommended precautions for their safety.

Diabetes mellitus

In patients with insulin-dependent diabetes, symptomatic hyperglycemia or diabetic ketoacidosis are seen.

Non-insulin-dependent diabetes mellitus can initially occur as symptomatic hyperglycemia or as non-ketotic hyperosmolar hyperglycemic coma. It is frequently asymptomatic and is diagnosed during a medical review or when the patient shows symptoms of a late complication.

Advice on Diabetes mellitus

  • In general, when patients with adequately treated IDDM they recognize the symptoms of DKA, inject themselves a quantity of insulin and seek promptly medical care.
  • It is important to notify the driver patient with diabetes that, if this situation (DKA) appears while driving, he should immediately stop the car and ask for help.
  • Even if they inject themselves insulin and feel better, they should not drive trying to arrive as soon as possible at the medical center. This clinical situation can progress without an adequate control toward loss of consciousness.
  • The diabetic patient who has suffered an episode of DKA needs a close medical monitoring, because frequent clinical and laboratory measurements are required on the progression of DKA and the relevant treatment adjustments.
  • Hypotension and coma influence adversely 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, and also the adjustment of diabetes.
  • The neurological sequels caused in some cases by acute brain edema responding 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 capacity for driving of the patient and advise him appropriately.
  • Diabetes mellitus associated with severe metabolic instability and requiring admission is disabling for driving.

Symptomatic hyperglycemia

With a normal and even increased diet, polyuria, polydipsia, and weight loss occur. Hyperglycemia, which causes significant glucosuria and osmotic diuresis, leads to dehydration. Polyuria is the initial manifestation.

In IDDM an increase generally occurs in plasma ketone bodies, causing diabetic ketoacidosis, sometimes in a few hours.

In NIDDM, symptomatic hyperglycemia can persist for days or weeks and the patient does not visit the physician. Sometimes, the visit is for an added complication such as the associated pruritus in women due to candidal vaginitis. At this point, the physician diagnoses the main problem, provides the relevant advice and prescribes the treatment.

Diabetic ketoacidosis (DKA)

In patients with IDDM, DKA can be triggered by missing insulin therapy or by an acute infection, injury, or heart attack, responsible for the regular treatment with insulin to be insufficient.

The liver synthesis increase in ketone bodies causes metabolic acidosis and respiratory compensation. 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. Signs of dehydration are commonly seen, with hypotension and hypokalemia.

Somnolence is a frequent later symptom, and, if the patient is not treated, it progresses to coma.

In general, when patients with adequately treated IDDM recognize the symptoms, they inject themselves a quantity of insulin and seek promptly medical care.

Non-ketotic hyperosmolar hyperglycemic coma (NKHHC)

It is a syndrome characterized by consciousness disorders, sometimes associated with focal or generalized seizures, significant dehydration and hyperglycemia, not associated with ketoacidosis.

It is a complication of the NIDDM previously undiagnosed or poorly controlled, and it has a very high mortality.

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

The most frequent triggering cause are the infections or the administration of drugs impairing tolerance to glucose or increasing fluid loss, such as glucocorticoids, phenytoin, immunosuppressants and diuretics.

The clinical manifestations are CNS disorders, dehydration, mild metabolic acidosis, and prerenal uremia. The consciousness level ranges between obtundation and coma. Transient hemiplegia sometimes occur.

The treatment is urgent and requires admission.

Advice on Non-ketotic hyperosmolar hyperglycemic coma

  • After recovery from an acute episode, close monitoring 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 permit him to drive safely, without startling due to hyper or hypoglycemia.