Type 1 diabetes and driving experience: an eight-year cohort study.

The driving habits of 250 drivers with Type 1 diabetes were reviewed 8 years after a previous assessment. At least 45 patients had died and 18 patients could not be traced. A postal questionnaire of the 187 survivors elicited a response from 89%. Fifty-six patients (34%) still held an unrestricted driving licence, demonstrating that a significant proportion of diabetic drivers had not declared diabetes to the licensing authority and/or their motor insurer and continued to ignore the statutory regulations. Fewer patients held Heavy Goods Vehicle licences than 8 years previously. Twenty-four patients had ceased driving as their driving skills had diminished with advancing age and ill health. This was a voluntary decision by all but two patients whose driving licences had been revoked. Thirty-nine patients admitted to a total of 55 road traffic accidents since 1979; 9 accidents (16%) were attributed to hypoglycaemia. Although dependent on patients' honesty and the accuracy of recall, the disclosed accident rates of 4.9 per million miles driven for male drivers and 6.3 per million miles for female drivers are comparable to the accident rate of a non-diabetic driving population of similar age.