A population-based study of risk factors for severe hypoglycaemia in a contemporary cohort of childhood-onset type 1 diabetes

Severe hypoglycaemia is a major barrier to optimising glycaemic control. Recent changes in therapy, however, may have altered the epidemiology of severe hypoglycaemia and its associated risk factors. The aim of this study was to examine the incidence rates and risk factors associated with severe hypoglycaemia in a contemporary cohort of children and adolescents with type 1 diabetes. Subjects were identified from a population-based register containing data on > 99% of patients (< 16 years of age) who were being treated for type 1 diabetes in Western Australia. Patients attend the clinic approximately every 3 months, where data pertaining to diabetes management, demographics and complications including hypoglycaemia are prospectively recorded. A severe hypoglycaemic event was defined as an episode of coma or convulsion associated with hypoglycaemia. Risk factors assessed included age, duration of diabetes, glycaemic control, sex, insulin therapy, socioeconomic status and calendar year. Clinical visit data from 1,770 patients, providing 8,214 patient-years of data between 2000 and 2011 were analysed. During follow-up, 841 episodes of severe hypoglycaemia were observed. No difference in risk of severe hypoglycaemia was observed between age groups. Good glycaemic control (HbA(1c) < 7% [53 mmol/mol]) compared with the cohort average (HbA(1c) 8-9% [64-75 mmol/mol]) was not associated with an increased risk of severe hypoglycaemia. When compared with patients on injection regimens, subjects aged 12-18 years on pump therapy were at reduced risk of severe hypoglycaemia (incidence risk ratio 0.6; 95% CI 0.4, 0.9). In this population-based sample of children and adolescents with type 1 diabetes, contemporary therapy is associated with a changed pattern and incidence of severe hypoglycaemia.