Childhood body mass index and development of type 2 diabetes throughout adult life-A large-scale danish cohort study.

OBJECTIVE: This study investigated how a wide spectrum of body mass index (BMI) values at ages 7 to 13 years are associated with type 2 diabetes throughout adulthood, including potential modifying effects of sex and birth weight.

METHODS: From the Copenhagen School Health Records Register, 292,827 individuals, born between 1930 and 1989, were followed in national registers for type 2 diabetes (women, n = 7,472; men, n = 11,548). Heights and weights were measured at ages 7 to 13 years.

RESULTS: Below-average BMIs, with few exceptions, were not associated with type 2 diabetes. Above-average BMIs had positive associations that were stronger in women than men, stronger in younger birth cohorts, and weaker with older age at diagnosis. Women born 1930-1947, 1948-1965, and 1966-1983 with above-average BMIs at 13 years (≥18.2 kg/m2 ) had hazard ratios (95% confidence intervals) ranging from 2.12 (1.91-2.36) to 2.84 (2.31-3.49) per z score when diagnosed at 30 to 47 years. Birth weight did not modify these associations.

CONCLUSIONS: Childhood BMIs below average are not associated with type 2 diabetes, whereas childhood BMIs above average are strongly associated with type 2 diabetes in adulthood, corresponding to excess risks even at levels below international definitions of overweight. The associations are stronger in women than men but are not affected by birth weight.