Diabetogenic elevated childhood total fat in South Asian and Black African/Caribbean people relates to adverse early life growth and low socioeconomic position compared with White people in the UK

Aims/hypothesis

Excess type 2 diabetes mellitus in minority ethnic groups remains unexplained, although greater fat mass makes a strong contribution. We hypothesised that height and weight through infancy in South Asian and Black African/Caribbean subgroups is more adverse than in White populations. These, allied to poor socioeconomic position, determine greater fat mass at age 7 years.

Methods

We report a secondary analysis from the UK Millennium Cohort Study, including 12,280 births of White ethnicity, and 358 of Indian, 650 of Pakistani, 268 of Bangladeshi, 163 of Black Caribbean and 277 of Black African ethnicity between 2000 and 2002. Birthweight was reported, and heights and weights were measured at ages 3, 5, 7, 11, 14 and 17 years. Bioimpedance captured fat mass, indexed to height, at ages 7, 11, 14 and 17 years. Standardised differences in anthropometry, using the White group as the comparator, were calculated. We explored the effect of early growth on ethnic differences in fat-mass index at age 7 years. Confounders included maternal anthropometry, smoking, infant breastfeeding, education, parental income and area-level socioeconomic deprivation.

Results

All minority ethnic subgroups had lower birthweight and accelerated infant height and weight growth compared with White children. By age 3 years, mean height was greater in all minority ethnic groups than in White children. This height advantage was progressively lost, first in Bangladeshi children. By age 17 years in boys/girls, Indians were 1.77/2.48 cm, Pakistanis 2.24/3.44 cm, Bangladeshis 4.83/5.95 cm and Black Caribbeans 1.64/0.49 cm shorter than White children. Heights were equivalent in Black African children. By age 17 years, all South Asian children were lighter, and Black African/Caribbean children heavier, than White children. The anthropometric gradient by ethnicity in children mirrored that in mothers. Girls from minority ethnic groups were more likely to be menstruating by age 11 years than White girls (range 12–27% vs 9%). At age 7 years, standardised fat-mass index (kg/m ² ) in boys/girls was 0.17/0.01 SDs greater in Indian, 0.21/0.04 in Pakistani, 0.18/0.16 in Bangladeshi, 0.48/0.35 in Black Caribbean and 0.37/0.75 in Black African children than in White children. These differences persisted to age 17 years. Weight gain to age 3 years, and in Black Africans/Caribbeans, adverse individual and neighbourhood socioeconomic position, contributed to ethnic differences in fat mass.

Conclusions/interpretation

Minority ethnic groups in the UK have poorer childhood growth than White children, achieving shorter height, greater fat mass and earlier female puberty. Mirroring of maternal and offspring ethnic subgroup gradients in height and weight indicates intergenerational transmission. Persistent adverse socioeconomic circumstances perpetuate ethnic adversity in early life accrual of body fat.

Data availability

All MCS data used in this analysis are available from UK Data Service with an end user licence ( https://ukdataservice.ac.uk/find-data/ ).

Graphical Abstract