Incidence and trends of type 1 diabetes before and after 2000 in the Western Pacific Region: A systematic review and meta-analysis

Objectives To undertake a systematic review of publications describing Type 1 diabetes (T1DM) incidence, trends over time and associated factors in the Western Pacific Region (WPR). Methods As per the PROSPERO-registered (CRD42019122646) protocol English (MEDLINE, Embase, Global Health) and Chinese data-bases (China National Knowledge Infrastructure, VIP, Wanfang) from onset to 31/12/2019 were searched for T1DM incidence in the WPR. Country level data extracted included annual crude incidence rates by sex, number of new cases per annum (p.a.) and cumulatively, and the population at-risk. A meta-analysis for T1DM incidence was performed (by region and narrow age-bands, where possible) with subgroup analyses by time and by region. Findings Forty-five population-based studies (21 from China), published 1973–2017, estimated T1DM incidence, mostly in youth, in 11 WPR countries. After 2000, mean annual T1DM incidence/100,000 person years aged 0–14 years ranged from 0.9 (95 % confidence intervals (CI), 0.6–1.3) in Fiji to 23.2 (95 % CI, 21.3–25.2) in Australia. The mean annual increase over time ranged from 2.8 % in Australia (1990–2002) to 14.2 % in Shanghai (1997–2011). T1DM incidence increased most in China (2.7-fold over 30-years) then Thailand (2-fold over 15-years). Most studies documented increasing incidence with age, though only two studies included people aged ≥ 20 years. Many, but not all studies reported significantly higher T1DM incidence in females vs. males. Conclusion T1DM incidence in the WPR is generally increasing, varying by age, sex, time and country. Results increase understanding of regional T1DM incidence and inform research and healthcare strategies.