Incidence and time trends of type 2 diabetes mellitus in youth aged 5–19 years: a population-based registry in Zhejiang, China, 2007 to 2013

BACKGROUND: The incidence of type 2 diabetes mellitus (T2DM) has been increasing globally over the past two decades in children and adolescents. There are currently a dearth of comprehensive population-based estimates of T2DM incidence and time trends in Chinese youth. METHODS: A population-based diabetes registry system in 30 representative districts in Zhejiang has been established for diabetes surveillance. All newly cases diagnosed by physicians in local hospitals and wards were registered using the registry system through web services and direct network report. The data were primarily abstracted from medical records in hospitals and wards. Annual incidence rates and their 95% confidence intervals (CIs) by age groups and sex were calculated per 100 000 person-years. Poisson regression models were applied to assess the effects of diagnosis year, age groups, sex and residence area on T2DM incidence and to examine the average annual percentage change in incidence. RESULTS: There were 392 newly diagnosed cases of T2DM (210 boys and 182 girls) over the study period. The mean annual age-standardized incidence was 1.96/100 000 person-years (95% CIs: 1.85–2.08). No statistically significant difference in incidence was found between boys and girls. However, the risk for T2DM was 1.49 times higher in urban area than in rural area. Besides, the mean annual incidence in youth increased with age. The age-standardized incidence was about 5 times higher in 2013 than in 2007. Steep rising incidence was observed, with an average annual increase of 26.6% in youth aged 10–19 years. CONCLUSIONS: The incidence of T2DM in children and adolescents was low in Zhejiang relative to other countries, whereas it increased markedly over the study period. Preventive strategies for T2DM are necessary in pediatric population.