HbA1c and the Prediction of Type 2 Diabetes in Children and Adults

Abstract

Objective: Long-term data validating glycated hemoglobin (HbA_1c) in assessing the risk of type 2 diabetes in children are limited. HbA_1c, fasting plasma glucose (FPG), and 2-h postload plasma glucose (2hPG) concentrations were measured in a longitudinal study of American Indians to determine their utility in predicting incident diabetes, all of which is thought to be type 2 in this population.

Research design and methods: Incident diabetes (FPG ≥126 mg/dL [7.0 mmol/L], 2hPG ≥200 mg/dL [11.1 mmol/L], HbA_1c ≥6.5% [8 mmol/mol], or clinical diagnosis) was determined in 2,095 children without diabetes ages 10-19 years monitored through age 39, and in 2,005 adults ages 20-39 monitored through age 59. Areas under the receiver operating characteristic (ROC) curve for HbA_1c, FPG, and 2hPG in predicting diabetes within 10 years were compared.

Results: During long-term follow-up of children and adolescents who did not initially have diabetes, the incidence rate of subsequent diabetes was fourfold (in boys) as high and more than sevenfold (in girls) as high in those with HbA_1c ≥5.7% as in those with HbA_1c ≤5.3%-greater rate ratios than experienced by adults in the same HbA_1c categories. Analyses of ROCs revealed no significant differences between HbA_1c, FPG, and 2hPG in sensitivity and specificity for identifying children and adolescents who later developed diabetes.

Conclusions: HbA_1c is a useful predictor of diabetes risk in children and can be used to identify prediabetes in children with other type 2 diabetes risk factors with the same predictive value as FPG and 2hPG.

Figure 1

Incidence of type 2 diabetes by HbA_1c category stratified by sex. Data are presented as incidence rates (cases/1,000 person-years) (A) and as incidence rate ratios (using the incidence in the lowest HbA_1c category as the reference rate) (B).

Figure 2

Incidence of type 2 diabetes by various glycemic measures at baseline stratified by age and sex. PG, plasma glucose. Data are presented as incidence rates (cases/1,000 person-years)

Figure 3

Sensitivity and specificity of HbA_1c, FPG, and 2hPG in identifying persons who developed diabetes within 10 years of screening among children and adolescents meeting ADA recommended criteria for screening (A) and among all children and adolescents in the study (B). The black circles indicate the current ADA thresholds for prediabetes for each of the three tests. The squares represent the sensitivity and specificity offered by different combinations of current ADA thresholds. The diamond indicates the arbitrary HbA_1c threshold of 5.4%.