Trends in the prevalence of type 2 diabetes and prediabetes in a Japanese community, 1988–2012: the Hisayama Study

Objective: We estimated secular trends in the prevalence of type 2 diabetes (T2DM) and prediabetes, and examined potential explanatory factors for these trends in a Japanese community. Methods: 4 cross-sectional examinations were conducted among subjects aged 40–79 years in 1988 (n = 2,490), 2002 (n = 2,856), 2007 (n = 2,761), and 2012 (n = 2,644). Glucose tolerance status was defined by a 75g oral glucose tolerance test. Results: The age-standardized prevalence of T2DM increased significantly in both sexes from 1988 to 2002, and thereafter it remained stable in men, and decreased nonsignificantly in women from 2002 to 2012. The age-standardized prevalence of prediabetes in men increased significantly between 1988 and 2002, but then decreased significantly. A similar trend was observed in women. The age-specific prevalence of T2DM increased greatly in men aged 60–79 years and women aged 70–79 years from 1988 to 2002, and then plateaued at a high level, while a significant decreasing trend was observed in women aged 40–49 years. The mean values of body mass index (BMI) increased steeply in these elderly subjects from 1988 to 2002, and remained at a high level, whereas those in middle-aged women decreased appreciably over the study period. Conclusions: Our findings suggest that in Japanese, there was no further increase in the prevalence of T2DM or prediabetes in either men or women in the 2000s. Secular change in the BMI level was likely to contribute to trends in the prevalence of T2DM, and thus the management of obesity may be important to reduce the prevalence of T2DM.