Section 7: Metabolic Diseases

1. Diabetes mellitus

  1. Insulin dependent diabetes mellitus (IDDM)
  2. Non-insulin dependent diabetes mellitus (NIDDM)

2. Hypothyroidism

3. Hyperthyroidism

Individuals in the acute phase of a metabolic disorder (eg, diabetes, Cushing’s disease, Addison’s disease, hyperfunction of the adrenal medulla, and thyroid disorders) may experience signs and symptoms that are incompatible with safe driving. Physicians should advise these individuals to refrain from driving (including driving to seek medical attention) until the symptoms have abated.

Section 7: Metabolic Diseases

Diabetes mellitus
Insulin dependent diabetes mellitus (IDDM)
No restrictions if the patient demonstrates satisfactory control of his/her diabetes, recognizes the warning symptoms of hypoglycemia, and meets required visual standards.

Patients should be counseled not to drive during acute hypoglycemic and hyperglycemic episodes. In addition, patients are advised to keep candy or glucose tablets within reach in their car at all times, in the event of a hypoglycemic attack.

For recommendations on peripheral neuropathy, see Section 4.

Patients who experience recurrent hypoglycemic or hyperglycemic attacks should not drive until they have been free of significant hypoglycemic or hyperglycemic attacks for three months.

Non-insulin dependent diabetes mellitus (NIDDM)
If the patient’s condition is managed by lifestyle changes and/or oral medications, there are no restrictions unless the patient develops related conditions (eg, diabetic retinopathy).

If the physician prescribes an oral medication that has a significant potential to cause hypoglycemia, he/she should counsel the patient as above.

Hypothyroidism Patients who experience symptoms that may compromise safe driving (eg, cognitive impairment, drowsiness, and fatigue) should be counseled not to drive until their hypothyroidism has been satisfactorily treated. If residual cognitive deficits are apparent despite treatment, a driver evaluation (including on-road assessment) performed by a driver rehabilitation specialist may be useful in determining the patient’s ability to drive safely.

Hyperthyroidism Patients who experience symptoms that may compromise safe driving (eg, anxiety, tachycardia, and palpitations) should be counseled not to drive until their hyperthyroidism has been satisfactorily treated and symptoms have resolved.

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