Changes in annual incidence of school children with type 2 diabetes in the Tokyo Metropolitan Area during 1975-2015.

OBJECTIVE: To analyze changes in the annual incidence of school students with type 2 diabetes detected by urine glucose screening at schools in the Tokyo Metropolitan Area during 1975-2015.

METHODS: Trend in temporal changes in the annual incidence rate were analyzed using a joinpoint regression model and the joinpoints. Annual percent change (APC) was calculated for each segmented line regression. Average annual percent change (AAPC) was also calculated for the whole period analyzed.

RESULTS: In total, 301 students, including 64 primary school students and 237 junior high school students, were diagnosed with type 2 diabetes. The overall incidence of type 2 diabetes (per 100 000/year) during the entire study period was 2.58 in all students, 0.80 in primary school students, and 6.41 in junior high school students. AAPC during the entire study period was estimated at -1.5 (not significant), and the incidence significantly increased during 1975-1982 (APC = 17.49, P < 0.05), but tended to decrease during 1982-2015 (APC = -1.01). In primary school students, the incidence significantly increased during1975-2010 (APC = 3.30, P < 0.05), and tended to decrease during 2010-2015 (APC = -29.61). In junior high school students, the incidence did not significantly change during the entire study period (APC = 0.06).

CONCLUSIONS: We found increasing trend in the overall incidence of school students with type 2 diabetes during 1975-1982, but a decreased tendency in recent years. This could be due to changes observed during the same time period in the primary school students. Lifestyle changes might contribute to improved incidence of childhood type 2 diabetes.