A large retrospective population-based cohort study from Taiwan has added weight to the association between enterovirus infection and onset of type 1 diabetes in childhood.

Diagnostic information was extracted from the Taiwanese National Health Insurance Research Database (NHIRD) for children aged 18 years or younger.

The study population included two groups. The first group had insurance claims that implicated clinical diagnosis of an enterovirus (EV) infection. This covered all EV-specific diagnoses, as well as infections caused by coxsackievirus, such as herpangina, hand foot and mouth disease, meningitis, pleurodynia, pericarditis and myocarditis. In total 576,967 children were included in these categories between 2000 and 2007.

The control group of children without evidence of these infections (non-EV) totalled 3,129,171.

The populations were matched by sex, birth year and index date of infection, giving a final matched study population of 57,0133 children in each arm. Mean age at entry and sex distribution was similar in both groups. Mean follow-up time was 6.4 years. Follow-up in person years was derived for each child from index date to December 2008.

The incidence of type 1 diabetes was lower in the non-EV group (4 vs 6 per 100,000 person-years), adjusted HR 1.48. (95% CI:1.19-1.83). EV infection was strongly associated with type 1 diabetes, exerting a 50% increased risk after one year of follow-up.

Children aged >10 years at entry also had a higher risk of type 1 diabetes HR 2.18 (95% CI:1.18-4.04).

Compared with the non-EV group, the EV group also had a significantly higher prevalence of atopic dermatitis, allergic rhinitis and bronchial asthma.

Findings from the DIAMOND study1 and EURODIAB2 have shown a rising epidemic of type 1 diabetes – a fact often forgotten when we discuss the massive numbers of cases of type 2 diabetes.

The increase in incidence seems to be across all genetic backgrounds, with variations more likely to be environmental than genetic.

GPs need to be alert to the presentation of type 1 diabetes in the younger child. A recent study showed that diabetes in this age group was often only diagnosed after multiple visits.

The Environmental Determinants of Diabetes in the Young (TEDDY) study has suggested that there is a link between coxsackievirus infection and type 1 diabetes in children in Finland, the country with the highest incidence of type 1 diabetes in children in the world.3 If such a link can be determined in the long term, a vaccination programme might reduce the risk of developing type 1 diabetes.

Dr Matthew Lockyer