Comparing hormonal and symptomatic responses to experimental hypoglycaemia in insulin- and sulphonylurea-treated Type 2 diabetes.

AIMS: Patients with diabetes rely on symptoms to identify hypoglycaemia. Previous data suggest patients with Type 2 diabetes develop greater symptomatic and hormonal responses to hypoglycaemia at higher glucose concentrations than non-diabetic controls and these responses are lowered by insulin treatment. It is unclear if this is as a result of insulin therapy itself or improved glucose control. We compared physiological responses to hypoglycaemia in patients with Type 2 diabetes patients treated with sulphonylureas (SUs) or insulin (INS) with non-diabetic controls (CON). METHODS: Stepped hyperinsulinaemic hypoglycaemic clamps were performed on 20 subjects with Type 2 diabetes, 10 SU-treated and 10 treated with twice-daily premixed insulin, and 10 age- and weight-matched non-diabetic controls. Diabetic subjects were matched for diabetes duration, glycated haemoglobin (HbA(1c)) and hypoglycaemia experience. We measured symptoms, counterregulatory hormones and cognitive function at glucose plateaux of 5, 4, 3.5, 3 and 2.5 mmol/l. RESULTS: Symptomatic responses to hypoglycaemia occurred at higher blood glucose concentrations in SU-treated than INS-treated patients [3.5 (0.4) vs. 2.6 (0.5) mmol/l SU vs. INS; P = 0.001] or controls [SU vs. CON 3.5 (0.4) vs. 3.0 (0.6) mmol/l; P = 0.05]. They also had a greater increase in symptom scores at hypoglycaemia [13.6 (11.3) vs. 3.6 (6.1) vs. 5.1 (4.3) SU vs. INS vs. CON; P = 0.017]. There were no significant differences in counterregulatory hormone responses or impairment of cognitive function among groups. CONCLUSIONS: Sulphonylurea-treated subjects are more symptomatic of hypoglycaemia at a higher glucose level than insulin-treated subjects. This may protect them from severe hypoglycaemia but hinder attainment of glycaemic goals.

Road traffic accidents and diabetes: insulin use does not determine risk.

AIMS: Progressive restrictions placed on insulin-treated patients with diabetes exclude them from driving group 2 and class C1 and D1 vehicles. This reflects an assumption that an increased risk of hypoglycaemia in these patients will cause road traffic accidents. These restrictions have been implemented without any consistent evidence that this is the case. The aim of the study was therefore to investigate whether the rate of road traffic collisions in insulin-treated patients was higher than that of the non-diabetic population using a population register-based study. METHODS: A historical cohort study combined information from the Devon and Cornwall Constabulary database on road traffic collisions with the district wide retinal screening database, to provide an anonymized matched database of road traffic collisions in the diabetic population. Accident rates were calculated in the diabetic population and compared to rates in the non-diabetic population using relative risks. RESULTS: The estimated overall annual accident rate for the non-diabetic population was 1469 per 100,000 vs. 856 per 100,000 for the diabetic population as a whole (Chi-squared, P < 0.001). On stratification of the groups by age, within the insulin-treated group there was no significant difference in the accident rate compared to the non-diabetic population, with relative risks between 0.51 [confidence interval (CI) 0.25-1.05] and 1.13 (CI 0.88-1.46). CONCLUSIONS: Our findings suggest that insulin-treated patients as a group do not pose an increased risk to road safety. They reiterate the need for an individualized risk-based assessment when considering driving restrictions.