2010 BC Guide in Determining Fitness to Drive

PercentFigure 1 - Prevalence of Diabetes in Canada1614121086420WomenMenBoth20-39 years 40 - 59 years 60 - 74 years 75+ years 20+ yearsAge GroupHypoglycemiaA study of people with type 1 diabetes conducted in 1993 estimated that the incidence of mildhypoglycemia (hypoglycemia for which a person is able to treat themselves) to be 28 episodesper person per year. The incidence of severe hypoglycemia was estimated to be 0.31 episodesper person, per year. Since the mid 1990’s there has been an increased therapeutic emphasis ontight glycemic control, which has been shown to significantly reduce the complications ofdiabetes. Unfortunately, the use of more intensive treatment to maintain glycemic control hasincreased the risk of hypoglycemia by as much as two or three times. This suggests that theseestimates on the prevalence of hypoglycemia in type 1 diabetes may be low.While people with type 2 diabetes who are treated with insulin are at risk of hypoglycemia, thefrequency is lower than for those with type 1 diabetes. The incidence of severe hypoglycemiafor type 2 diabetes treated with insulin secretagogues is about 1 to 2% per year, with higher riskfor longer use, older age, and the use of chlorpropamide and other long-acting secretagogues.The concomitant use of beta blockers and insulin previously has been thought to increase the riskof hypoglycemia; however, this theoretical concern is not often seen in practice.For anyone with diabetes, a history of severe hypoglycemia, hypoglycemia unawareness, andlow blood glucose levels are consistent predictors of future hypoglycemia.Hypoglycemia unawarenessIt is estimated that 25% of all those treated with insulin will experience one or more episodes ofhypoglycemia unawareness. In type 1 diabetes, hypoglycemia unawareness increases with theduration of diabetes and the likelihood increases if autonomic neuropathy is present. In type 2diabetes, hypoglycemia unawareness is relatively uncommon.87