Being underweight in adolescence is independently associated with adult-onset diabetes among women: The Japan Nurses' Health Study

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.