GIDM. GIORNALE ITALIANO DI DIABETOLOGIA E METABOLISMO
Abstract
Background. Recently glycated hemoglobin (A1c) ≥ 48 mmol/mol
has been included among the diagnostic criteria for type 2 diabetes
mellitus (DM2) in adults, while borderline levels of 39-47
mmol/mol indicate impaired glycemia (pre-diabetes). In overweight/
obese children an oral glucose tolerance test (OGTT) is
used to screen for DM2 and pre-diabetic status (impaired fasting
glucose [IFG] and impaired glucose tolerance [IGT]). A1c could
therefore theoretically replace OGTT as a screening test in children
at risk for DM2, IFG, IGT, or insulin resistance (IR).
Methods. Italian patients aged less than 18 years, consecutively
assessed for overweight/obesity (BMI > 85th percentile) in our Pediatric
Endocrinology Outpatient Care Unit between July 2011
and December 2012, were included. A1c was determined for each
patient (IFCC method) and an OGTT was done (blood glucose
and insulin levels at 0, 60 and 120 min).
Results. Data were collected from 225 patients (105 males),
mean age 11.2 ± 3.2 years and mean BMI 27.6 ± 4.7 (77% with
BMI > 95th percentile). Mean A1c was 36.2 ± 4.9 mmol/mol (range
16-50). Three cases had IFG, 12 IGT and 83 IR. In 71 cases
(32%) with borderline A1c, none had IFG, 5 had IGT, and 37 had
IR. The only child known to be diabetic had borderline A1c. Sensitivity
and specificity were 0, 67.6% for IFG, 41.6, 68.8% for IGT,
45.1, 76.1% for IR.
Conclusions. A1c is not sensitive enough for detecting diabetic
and pre-diabetic status, so it would not be a reliable tool. Given the
intermediate specificity of borderline A1c 39-47 mmol/mol to identify
pre-diabetic status, confirmation with an OGTT is always advisable.
In our series, borderline A1c was better at predicting IR.
