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 childh ood growth on beta-cell activity and insulin sensitivity in 7-year-old chil dren. Methods. Insulin, des-31,32 proinsulin, proinsulin, non-esterified fatty ac ids and glucose concentrations were measured in oral glucose tolerance test s in 152 South African children for whom longitudinal weight data was avail able. Results. Children with low weights at birth and 7 years (low-low) had relat ively low beta-cell activity whereas children with low birth weight and hig h 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 h igh birth weights. When each insulin-related peptide was expressed as a per centage of all these peptides the low-low children had the highest percenta ge 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-es terified fatty acid concentrations were lowest and their suppression post-g lucose load highest in the low-high group. Conculsion/interpretation. Poor fetal and neonatal growth give rise to low beta-cell numbers compensated for by increased efficiency of proinsulin pro cessing 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 insul in sensitivity with poor fetal coupled with high postnatal growth being det rimental to these processes but not detrimental to the suppression of lipol ysis.