How does exposure to overnutrition in utero lead to childhood adiposity? Testing the insulin hypersecretion hypothesis in the EPOCH cohort.

Abstract

Our aim was to explore metabolic pathways linking overnutrition in utero to development of adiposity in normal-weight children. We included 312 normal-weight youth exposed or unexposed to overnutrition in utero (maternal BMI ≥25kg/m2 or gestational diabetes). Fasting insulin, glucose and body composition were measured at age ~10years (baseline) and ~16years (follow-up). We examined associations of overnutrition in utero with baseline fasting insulin, followed by associations of baseline fasting insulin with adiposity (BMI z score [BMIZ], subcutaneous adipose tissue [SAT], visceral adipose tissue [VAT]), insulin resistance (HOMA-IR) and fasting glucose during follow-up. >All participants were normal weight at baseline (BMIZ -0.32 ± 0.88), with no difference in BMIZ for exposed vs unexposed youth (p = 0.14). Of the study population, 47.8% were female sex and 47.4% were of white ethnicity. Overnutrition in utero corresponded with 14% higher baseline fasting insulin (geometric mean ratio 1.14 [95% CI 1.01, 1.29]), even after controlling for VAT/SAT ratio. Higher baseline fasting insulin corresponded with higher BMIZ (0.41 [95% CI 0.26, 0.55]), SAT (13.9 [95% CI 2.4, 25.4] mm2), VAT (2.0 [95% CI 0.1, 3.8] mm2), HOMA-IR (0.87 [95% CI 0.68, 1.07]) and fasting glucose (0.23 [95% CI 0.09, 0.38] SD). Overnutrition in utero may result in hyperinsulinaemia during childhood, preceding development of adiposity. However, our study started at age 10years, so earlier metabolic changes in response to overnutrition were not taken into account. Longitudinal studies in normal-weight youth starting earlier in life, and with repeated measurements of body weight, fat distribution, insulin sensitivity, beta cell function and blood glucose levels, are needed to clarify the sequence of metabolic changes linking early-life exposures to adiposity and dysglycaemia.