Relation between weight gain and beta-cell secretory activity and non-esterified fatty acid production in 7-year-old African children: results from the Birth to Ten study.

AIMS/HYPOTHESIS: This study aimed to assess the effects of fetal and childhood growth on beta-cell activity and insulin sensitivity in 7-year-old children.
METHODS: Insulin, des-31,32 proinsulin, proinsulin, non-esterified fatty acids and glucose concentrations were measured in oral glucose tolerance tests in 152 South African children for whom longitudinal weight data was available.
RESULTS: Children with low weights at birth and 7 years (low-low) had relatively low beta-cell activity whereas children with low birth weight and high weight at 7 years (low-high) had relatively high beta-cell activity. The low-low group had higher 30-min glucose concentrations than children with high birth weights. When each insulin-related peptide was expressed as a percentage of all these peptides the low-low children had the highest percentage of insulin but the lowest of the prohormones. The low-high children had the lowest percentage of insulin but the highest of the prohormones. Non-esterified fatty acid concentrations were lowest and their suppression post-glucose load highest in the low-high group. CONCLUSION/
INTERPRETATION: Poor fetal and neonatal growth give rise to low beta-cell numbers compensated for by increased efficiency of proinsulin processing to insulin. Poor fetal followed by higher postnatal growth results in low beta-cell numbers and reduced whole-body glucose uptake which leads to reduced efficiency in the processing of proinsulin. Growth in utero and postnatally therefore have profound effects on beta-cell activity and insulin sensitivity with poor fetal coupled with high postnatal growth being detrimental to these processes but not detrimental to the suppression of lipolysis.