This study confirms Ireland as a high-incidence country for type 1 diabetes whilst demonstrating that the previous marked increase in IR from 16.3 cases/100,000/year in 1997 has not continued. Ongoing monitoring through the robust mechanism of the ICDNR is required to clarify whether this is a fluctuation or if the incidence of T1D diabetes has stopped rising in our population. Alternatively, this apparent stabilisation may reflect a shift to a later age at diagnosis. "What is known :" • The incidence of Type 1 diabetes (T1D) is increasing in most populations worldwide although in certain high-incidence populations, it may be stabilising • There was a marked increase in T1D in Ireland between 1997 and 2008 • T1D incidence increases with affluence "What is New:" • The high incidence of T1D in Ireland has been confirmed at 28.8 cases/100,000/year in 2013 and has been effectively stable in the period 2008-2013 • Incidence is highest in Irish 10-14 year olds • Changes in incidence possibly reflecting life style and economic climate • Marked seasonality of diagnosis confirmed.

Aim The global incidence of type 1 diabetes mellitus (T1DM) varies considerably geographically. Ireland has a high incidence of T1DM. Incidence accelerated between 1997 and 2008, although more recent data (2008–2013) suggested stabilisation in the incidence rate (IR). This study sought to determine IRs for 2014 to 2018. Methods Incident cases were prospectively recorded through the established Irish Childhood Diabetes National Register (ICDNR). Cases were verified, and IRs were calculated. Capture‐recapture methodology was identical to previous studies. Age and seasonality data were compared. Results A total of 1429 cases were reported (age range 0.45–14.98 years), with significantly more males (772, 54%) and male‐to‐female ratio of 1.17 (95% CI 1.05, 1.29). Standardised IRs for T1DM in the period were 28.0; 29.6; 30.9; 27.0; and 27.1/100,000/year, respectively. There was a slight reduction in standardised IR, more marked in females than males (9.9% v 1.6%). The highest IR remains in the 10‐ to 14‐year‐old age group (44% of total cases). Seasonality of diagnosis is persistently higher in autumn and winter. Conclusion Ireland remains a high incidence country, despite a minor reduction in incidence rates. Ongoing incidence monitoring through national registers is vital to inform healthcare services, research relating to aetiology and paediatric diabetes management.