A1c has been well proven to be a useful test in predicting type 2 diabetes in adults. This longterm, impressive study reveals that A1c could be meaningfully applied in children too. In addition, the test is comparable with fasting and 2 hour load glucose tests.
A group of 2100 children were followed for about 25 years. A1c ≥5.7% predicts 400% increased risk of diabetes in boys and 700% in girls in 10 years.
OBJECTIVE: Long-term data validating glycated hemoglobin (HbA1c) in assessing the risk of type 2 diabetes in children are limited. HbA1c, 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, 2hPG ≥200 mg/dL, HbA1c ≥6.5%, 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 HbA1c, 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 HbA1c ≥5.7% as in those with HbA1c ≤5.3% —greater rate ratios than experienced by adults in the same HbA1c categories. Analyses of ROCs revealed no significant differences between HbA1c, FPG, and 2hPG in sensitivity and specificity for identifying children and adolescents who later developed diabetes.
CONCLUSIONS: HbA1c 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.
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The prevalence of type 2 diabetes has increased among youth in the U.S.; between 2001-2009, there was a 30.5% rise in the overall prevalence of diagnosed diabetes. Many youth diagnosed with type 2 diabetes have poor glycemic control and experience higher rates of cardiovascular disease risk markers, fatty liver disease, and early evidence of microvascular complications. This highlights the need for early detection of prediabetes to prevent the increase in diabetes and its associated cardiometabolic risk factors.
The American Diabetes Association (ADA) recommends glycated hemoglobin (HbA1c) as a diagnostic test for diabetes. This guideline is based on adult epidemiological studies that show an association between increased HbA1c and the risk for microvascular complications. Longitudinal studies investigating the relationship between HbA1c in childhood and the risk of developing diabetes are lacking. In addition, few pediatric studies have compared HbA1c with other measures of glycemia such as fasting plasma glucose (FPG) and 2-h postload plasma glucose (2hPG).
The ADA recommends screening for type 2 diabetes or prediabetes using HbA1c in asymptomatic children and adolescents aged ≥10 years with a BMI ≥85th percentile for age and sex, based on Centers for Disease Control and Prevention growth charts, and at least two additional type 2 diabetes risk factors. Risk factors include type 2 diabetes in a first- or second-degree relative, minority race or ethnicity, signs of insulin resistance, or maternal history of diabetes or gestational diabetes during the child’s gestation.
Measuring HbA1c is convenient in children because it does not require fasting, and a single test can be used to both diagnose and monitor glycemic control, thereby facilitating sample collection and compliance in children. In addition, HbA1c reflects chronic glycemia and has less preanalytical and analytical variability than FPG and 2hPG.
The ADA includes HbA1c as a diagnostic measure for diabetes because of its association with long-term microvascular complications in adults, including retinopathy and diabetic nephropathy. This recommendation included adult participants from the same study population we describe here, and we reported previously that HbA1c and FPG measurements in adults were just as useful as 2hPG in predicting the risk of microvascular complications.
The strengths of our study include both a large pediatric and adult cohort, examinations with all three glycemia tests performed at the same time, and an extensive longitudinal follow-up period. Also, all of our laboratory tests, including HbA1c assays, were performed at the same laboratory using standardized methods.
In summary, higher HbA1c at baseline predicted a higher incidence of diabetes in both children and adults. Although the absolute incidence rates were greater in adults, the incidence rate ratios were the same or greater in children. When incidence rates were compared with various abnormalities in glycemic measures (HbA1c, FPG, and 2hPG) at baseline, individually or combined, HbA1c performed as well as FPG and 2hPG in boys, girls, and men, but not as well as 2hPG in adult women. We therefore conclude that HbA1c can be used to assess risk for diabetes in children or to identify children with prediabetes with the same confidence as FPG or 2hPG.