Socioeconomic disadvantage is associated with higher morbidity and poorer health behavior, despite higher rates of health service utilization (1). In a study of American children with diabetes, lower socioeconomic status was associated with poorer glycemic control and more hypoglycemic episodes (2). In an audit of 1,190 children with type 1 diabetes aged <15 years, we examined whether socioeconomic disadvantage or urban/rural location affect metabolic control in Australia, which has universal health insurance and subsidies for diabetes supplies.

Case attainment, based on the Diabetes Register, was 67% of all eligible children living in New South Wales (NSW) and the Australian Capital Territory (ACT). There were 649 girls and 541 boys recruited from three multidisciplinary hospital-based pediatric diabetes units, four private city-based pediatric diabetes practices, and 18 rural diabetes outreach clinics. Social disadvantage was assessed using a graded postcode-based social disadvantage risk score (SDRS) derived from nine risk indicators (3). HbA1c was assayed in a central laboratory using the Bio-Rad Variant HPLC Capillary Collection System (Bio-Rad Laboratories, Munich, Germany). Level II Laboratory Certification of Traceability to the Diabetes Control and Complications Trial (DCCT) reference method was obtained from the University of Missouri Secondary Reference Laboratory no. 1.

The median HbA1c was 8.2% (interquartile range 7.6–9.1%). The significant predictors of HbA1c in a multiple regression model were longer duration (b = 0.04, P = 0.0001) and insulin dose per kilogram (b = 0.44, P = 0.0001). After excluding subjects with duration <2 years, a more complex model resulted, with a significant interaction between age and duration: HbA1c = 8.74 + 0.28 (insulin per kilogram) − 0.15 (duration) − 0.05 (age) + 0.01 (duration × age).

Rural children lived in areas of lower social advantage (SDRS −0.4 ± 0.6) than city-based children cared for in either the public sector (0.4 ± 0.7) or the private sector (1.0 ± 0.7) (P < 0.0001). There was no significant difference in the median HbA1c levels among the 25 different centers (range 7.7–8.7%), and SDRS was not significant in the multiple regression model. There was no difference in the metabolic control of children living in rural locations compared with those from urban locations (median HbA1c 8.2% in both).

The incidence of severe hypoglycemia (unconsciousness or seizures) was 36 per 100 patient-years. HbA1c, urban/rural location, or SDRS were not significant predictors of hypoglycemia in a Poisson regression model. No significant differences were found for either metabolic control or rate of hypoglycemia between children cared for in the public or private system, despite significantly greater social advantage in the latter group.

The median HbA1c of 8.2% in NSW/ACT is comparable with results from the multinational Hvidore study (mean HbA1c 8.6%, DCCT equivalent 8.3%) (4). In that study, there was significant variation in metabolic control among 22 centers from 18 countries. In contrast, the audit from NSW/ACT shows remarkable homogeneity in metabolic control among centers, regardless of location, socioeconomic status, or system of care.

This study was supported by an educational grant from Novo Nordisk and Bio-Rad Australia.

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Address correspondence to Dr. Maria Craig, Ray Williams Institute of Paediatric Endocrinology, Diabetes and Metabolism, The Children’s Hospital at Westmead, Locked Bag 4001, Westmead, NSW 2145, Australia. E-mail: [email protected].