Abstract
AIMS/INTRODUCTION: To examine the association between adult-onset diabetes and life-course bodyweight changes. MATERIALS AND METHODS: In a cross-sectional study, 17,398 Japanese female nurses aged ≥30 years completed a self-administered questionnaire in 2001-2007. Bodyweight indices were calculated for three life stages: birthweight (adjusted for gestational age), body mass index (BMI) at age 18 years and current BMI. Odds ratios for being diagnosed with adult-onset diabetes were calculated according to the combined bodyweight categories of two life stages: at birth and age 18 years; and at age 18 years and the survey (current). Path analysis was carried out to decompose the effect of each bodyweight index into direct and mediating effects. RESULTS: After adjustment for age at survey and parental diabetes history, "low" birthweight (<25th percentile), when combined with either "low" or "high" BMI (≥75th percentile) at age 18 years, had significant odds ratios (2.32, 95% confidence interval [CI] 1.22-4.44; 3.69, 95% CI 2.12-6.42, respectively) compared with the group of "middle" category (25th-74th percentile) at both life stages. The combination of "low" BMI at age 18 years and "high" current BMIs showed the highest odds ratio (7.97, 95% CI 3.97-16.00). Among women without parental diabetes history, "low" BMI at age 18 years showed a significantly high odds ratio (2.25, 95% CI 1.01-4.99), even when combined with the "middle" category of current BMI. Path analysis showed that both birthweight and BMI at age 18 years had a negative direct effect on adult-onset diabetes. CONCLUSIONS: Underweight at adolescence, as well as overweight, is a potential risk factor for adult-onset diabetes among Japanese women.