MedWire News: Glycated hemoglobin (HbA1c) is better than fasting plasma glucose (FPG) for predicting impaired glucose tolerance (IGT) in obese children and adolescents, suggest study findings.
"An HbA1c value of 5.8% should be used as a screening tool to identify children and adolescents with IGT," write Jin Hwang (Ajou University Hospital, Suwon, South Korea) and team in Diabetic Medicine.
The 2010 American Diabetes Association (ADA) guidelines recommend that an HbA1c level of 5.7% or more can be considered an indicator of increased risk for diabetes.
"However, HbA1c cut-off points have been based on studies performed exclusively in adults," say the researchers. "There have been few studies on HbA1c as a predictive marker in children and adolescents."
The team therefore investigated whether HbA1c level could predict IGT in obese (>95th percentile for age and gender) and overweight (BMI >85th and ≤95th percentile for age and gender) children and adolescents without diabetes.
The researchers studied chart reviews for 126 obese and overweight children (mean age 9.9 years) who completed an oral glucose tolerance test (OGTT) between 2003 and 2010. They then collected information on each child's family history of diabetes, weight, height, body mass index, and HbA1c level.
The researchers report that 110 (87.3%) of the children were obese and 16 (12.7%) were overweight.
The study revealed that 34 of the patients had IGT (2-hour plasma glucose ≥7.8 and <11.1 mmol/L), 10 had silent diabetes (2-hour plasma glucose ≥11.0 mmol/L), and 22 had impaired fasting glucose (FPG ≥5.6-6.9 mmol/L).
Of the 34 patients with IGT, 25 (73.5%) were found to have normal fasting blood glucose based on the FPG threshold of 5.6 mmol/L or more, which only had a sensitivity of 29.4% and a specificity of 89.1%.
"The majority of children with abnormal glucose tolerance turned out to have normal fasting plasma glucose values," say Hwang et al.
Receiver operating characteristic analysis revealed that the optimal cut-off point for HbA1c related to IGT diagnosed by OGTT was 5.8%, which was associated with 64.7% sensitivity and 61.6% specificity.
The researchers say that fasting glucose level is an insensitive method for detecting impaired glucose regulation in obese children and adolescents and that an HbA1c of 5.8% can be used as a sensitive screening test to identify such individuals.
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