The between-day reproducibility of fasting, satiety-related analytes, in 8 to 11 year-old boys

The aim of the present study was to establish the between-day reproducibility of fasting plasma GLP-17-36, glucagon, leptin, insulin and glucose, in lean and overweight/obese 8-11 y boys. A within-groups study design was utilised wherein the boys attended two study days, separated by 1 week, where a fasting fingertip capillary blood sample was obtained. Deming regression, mean difference, Bland-Altman limits of agreement (LOA) and typical imprecision as a percentage coefficient of variation (CV %), were utilised to assess reproducibility between-days. On a group level, Deming regression detected no evidence of systematic or proportional bias between-days for all of the satiety-related analytes however, only glucose and plasma GLP-17-36 displayed low typical and random imprecision. When analysed according to body composition, good reproducibility was maintained for glucose in the overweight/obese boys and for plasma GLP-17-36, in those with lean body mass. The present findings demonstrate that the measurement of glucose and plasma GLP-17-36 by fingertip capillary sampling on a group level, is reproducible between-days, in 8-11 y boys. Comparison of blood glucose obtained by fingertip capillary sampling can be made between lean and overweight/obese 8-11 y boys. Presently, the comparison of fasting plasma GLP-17-36 according to body weight is inappropriate due to high imprecision observed in lean boys between-days. The use of fingertip capillary sampling in the measurement of satiety-related analytes, has the potential to provide a better understanding of mechanisms that affect appetite and feeding behaviour in children.