Introduction The geographical incidence of type 1 diabetes mellitus in children varies widely worldwide. Both genetic and environmental factors have been implicated.

Objective Evaluated the incidence of type 1 diabetes in children in Tunisia and identified the epidemiologic characteristics.

Patients and methods We conducted a retrospective study of new cases of type 1 diabetes in children (0 -15) years, discovered during the years 2009–2010–2011 in 17 paediatric centre from Tunisia.

We divided our patients into 3 groups: group 1 (0–4 years), Group 2 (5–9 years) and group 3 (10–15 years). These three groups were compared with regard to their epidemiological characteristics.

Results We identified 627 diabetic children. They were 332 boys and 295 girls. The incidence was estimated at 8.5/100 000 children under 15 years and 9.6/100 000 children (0–4 years). The incidence was 7.7/100 000 children (0- 15 years) in 2009, it passed to 8.93/100 000 in 2011.

The patients were aged 0–4 years in 33% of cases, 5–9 years in 34.1% of cases and 10–15 years in 32.9% of cases.

The discovery of diabetes was in winter in 35% of cases. Parental consanguinity was noted in 31.2% of cases.

Conclusion Type 1 diabetes is a public health problem in Tunisia, its incidence increases and the age of diagnosis shifts to ages younger. Winter predominance of discovery supports the hypothesis of a triggering viral infection.