ORIGINAL ARTICLE Increasing incidence of type 2 diabetes in New Zealand children <15 years of age in a regional-based diabetes service, Auckland, New Zealand Natalia Sjardin, 1 Peter Reed, 2 Ben Albert, 3 Fran Mouat, 4 Phillipa J Carter, 4 Paul Hofman, 3 Wayne Cutfield, 3 Alistair Gunn 5 and Craig Jefferies 4 1 Department of Paediatrics and Physiology, 3 Liggins Institute, and 5 Faculty of Medical Health Sciences, University of Auckland, 2 Research Office, Auckland District Health Board and 4 Auckland District Health Board, Starship Children’s Hospital, Auckland, New Zealand Aim: It is important to understand whether type 2 diabetes mellitus (T2DM) is increasing in childhood for health-care planning and clinical man- agement. The aim of this study is to examine the incidence of T2DM in New Zealand children, aged <15 years from a paediatric diabetes centre, Auckland, New Zealand. Methods: Retrospective analysis of prospectively collected data from a population-based referral cohort from 1995 to 2015. Results: Hundred and four children presented with T2DM over the 21-year period. The female:male ratio was 1.8:1, at mean (standard deviation) age 12.9 (1.9) years, body mass index standard deviation score +2.3 (0.5), blood sugar 15.3 (8.5) mmol/L, HbA1c 76 (28) mmol/mol. At diagnosis, 90% had acanthosis nigricans and 48% were symptomatic. In all, 33% were Maori, 46% Pacific Island, 15% Asian/Middle Eastern and 6% European. There was a progressive secular increase of 5% year on year in incidence. The overall annual incidence of T2DM <15 years of age was 1.5/100 000 (1.2–1.9) (95% confidence interval), with higher rates in Pacific Island (5.9/100 000) and Maori (4.1/100 000). Conclusions: The incidence of T2DM in children <15 years of age in New Zealand has increased progressively at 5%/year over the last 21 years. The risk was disproportionately associated with girls and children from high-risk ethnic groups. Key words: adolescence; deprivation; ethnicity; incidence; obesity; type 2 diabetes. What is already known on this topic 1 Type 2 diabetes mellitus (T2DM) occurs in children and adoles- cents from high-risk ethnic groups. 2 T2DM in adolescents often presents with classic symptoms of diabetes. 3 Incidence rates vary markedly geographically. What this paper adds 1 There has been a progressive increase in incidence of T2DM. 2 Pacific Island (5.9/100 000) and Maori (4.1/100 000) children have the highest incidence of T2DM. 3 In all, 48% of cases of T2DM continue to present with classic symptoms of diabetes. The onset of type 2 diabetes mellitus (T2DM) in late childhood and in adolescence is increasingly recognised in paediatric popu- lations around the world. 1–3 There are low incidences in European countries, increasing incidence in Asian countries and a highly persistent incidence in Native American Indians and indigenous people of Canada and Australia. 4–9 Historically, cases of T2DM in children were rare and the first cases were reported in Australia, for example, only in the 1990s. 10–12 Recent studies from China, Japan and Western Australia suggest that the risk of T2DM in children and adolescents continues to increase. 8,11,13 For example, in China, the age-standardised incidence increased approximately fivefold from 2007 to 2013. 8 Similarly, in the USA, T2DM in youth increased by 7.1% annually, from 9.0 cases per 100 000 youths per year in 2002–2003 to 12.5 cases per 100 000 per year in 2011–2012. 7,14 New Zealand has a relatively high incidence of type 1 diabetes, with an annual increase in incidence of 3–5%. 15 By contrast, although T2DM is still relatively uncommon in childhood and adolescence, 10,16 we have previously reported that the incidence of T2DM in childhood and adolescence increased fivefold from 1995 to 2007. 10 Encouragingly, the incidences appeared to peak in 2003 and then stabilise at a lower level. It is critical for public policy to know if this apparent stabilisation was real or a tempo- rary fluctuation. In developed countries most cases of T2DM occur in high-risk ethnic groups and/or in association with deprivation. 9,10,12,16,17 New Zealand has a population of 4.2 million people, the majority of whom are of European descent but with a significant Correspondence: Dr Craig Jefferies, Auckland District Health Board, Starship Children’s Hospital, Private Bag 92024, Auckland Mail Centre, Auckland 1142, New Zealand. Fax: +64 9375 4371; email: craigj@adhb. govt.nz Conflict of interest: None declared. Accepted for publication 13 March 2018. doi:10.1111/jpc.13924 Journal of Paediatrics and Child Health (2018) © 2018 Paediatrics and Child Health Division (The Royal Australasian College of Physicians) 1