Haemoglobin A1c is not a surrogate for glucose and insulin measures for investigating the early-life and childhood determinants of insulin resistance and type 2 diabetes in healthy children: an analysis from the Avon Longitudinal Study of Parents and Children (ALSPAC)

Aims Research into early life and childhood determinants of insulin resistance and Type 2 diabetes are complicated by requirements for fasting blood samples and glucose tolerance tests. We investigated haemoglobin A1c (HbA1c), a marker of glycaemia measured in non-fasting blood, as an alternative. Methods HbA1c was measured in 1645 children aged 9–11 years without diabetes from the Avon Longitudinal Study of Parents and Children. Thirty-nine children had two HbA1c measurements. Data on parental, child and potential confounding factors were collected prospectively from questionnaires, medical records and direct examination. Data from a shortened 30-min oral glucose tolerance test were available for 431 children at age 8 years. Body composition was measured by dual-energy X-ray absorptiometry. Results Mean (sd) HbA1c was 4.91(0.29)%. HbA1c increased with age and was higher in boys compared with girls, non-white compared with white children, and in children with anaemia. Mean difference between repeated HbA1c measurements was 0.01%. HbA1c was weakly positively associated with fasting glucose (β = 0.066%/mmol/l, P = 0.05), but was not associated with 30-min glucose, fasting or 30-min insulin, or homeostasis model assessment-insulin resistance. HbA1c was weakly inversely associated with weight sd score (β = −0.02%/unit, P = 0.004), body mass index sd score (β = −0.02%/unit, P = 0.002), and total body fat (β = −0.003%/kg, P = 0.06) and lean mass (β = −0.011%/kg, P = 0.01), but was not associated with birthweight or breastfeeding. Conclusions HbA1c is not a good marker of fasting or post-load glucose and insulin measures in healthy children, and is not a viable alternative to these measures for investigating the determinants of insulin resistance and Type 2 diabetes in children.