Normal Hemoglobin A1c Variability in Early Adolescence: Adult Criteria for Prediabetes Should Be Applied with Caution.

American Diabetes Association adult criteria are used to screen youth for diabetes, but little is known about normal glycemia in youth. In the HEALTHY Study (total n = 8814), hemoglobin A1c was ≥5.7% in 2% of normal weight youth. This suggests need for cautious interpretation of prediabetes hemoglobin A1s in youth.

Hemoglobin A1c Accurately Predicts Continuous Glucose Monitoring-Derived Average Glucose in Youth and Young Adults With Cystic Fibrosis.

OBJECTIVE: In cystic fibrosis (CF), hemoglobin A1c (HbA1c) is thought to underestimate glycemia. However, few studies have directly assessed the relationship between HbA1c and average glucose in CF. We determined the relationships among glycemic markers-HbA1c, fructosamine (FA), glycated albumin (%GA), and 1,5-anhydroglucitol (1,5-AG)-and continuous glucose monitoring (CGM) in CF, hypothesizing that alternate markers would better predict average sensor glucose (ASG) than HbA1c. RESEARCH DESIGN AND METHODS: CF participants and a group of healthy control subjects (HCs), ages 6-25 years, wore CGM for up to 7 days. Pearson correlations assessed the relationships between CGM variables and HbA1c, FA, %GA, and 1,5-AG. The regression line between HbA1c and ASG was compared in CF versus HC. Linear regressions determined whether alternate markers predicted ASG after adjustment for HbA1c. RESULTS: CF (n = 93) and HC (n = 29) groups wore CGM for 5.2 ± 1 days. CF participants were 14 ± 3 years of age and 47% were male, with a BMI z score -0.1 ± 0.8 and no different from HCs in age, sex, or BMI. Mean HbA1c in CF was 5.7 ± 0.8% (39 ± 9 mmol/mol) vs. HC 5.1 ± 0.2% (32 ± 2 mmol/mol) (P < 0.0001). All glycemic markers correlated with ASG (P ≤ 0.01): HbA1c (r = 0.86), FA (r = 0.69), %GA (r = 0.83), and 1,5-AG (r = -0.26). The regression line between ASG and HbA1c did not differ in CF versus HC (P = 0.44). After adjustment for HbA1c, %GA continued to predict ASG (P = 0.0009) in CF. CONCLUSIONS: HbA1c does not underestimate ASG in CF as previously assumed. No alternate glycemic marker correlated more strongly with ASG than HbA1c. %GA shows strong correlation with ASG and added to the prediction of ASG beyond HbA1c. However, we are not advocating use of HbA1c for diabetes screening in CF based on these results. Further study will determine whether glycemic measures other than ASG differ among different types of diabetes for a given HbA1c.

Congenital adrenal hyperplasia and the second newborn screen.

OBJECTIVE: To evaluate the effectiveness of a second newborn screen for congenital adrenal hyperplasia (CAH) in the state of Colorado and report characteristics associated with cases identified on the first versus second screen. STUDY DESIGN: Colorado implemented newborn screening for CAH with 17-hydroxyprogesterone beginning August 2000. The first screening is performed within 72 hours of life and the second between 8 and 14 days of life. We compared infants diagnosed on the basis of the first versus second newborn screen. RESULTS: The first screen identified 29 cases of which 28 represented classical CAH. The incidence of classical CAH on the first screen was 1:24,766. The second screen identified 17 additional cases, of which 11 represented classical CAH. Combined, the incidence of classical CAH was 1:17,789. The sensitivity of the first screen was 71.79%. The false negative rate of the first screen was 28.2%. In the absence of a second screen, 1:47,824 infants would have been missed. Infants diagnosed on the first screen had higher 17-hydroxyprogesterone values compared with those diagnosed on the second screen (P = .0008). CONCLUSIONS: The use of a single newborn screen for CAH missed nearly 30% of classical CAH cases in Colorado. Addition of a second screen, therefore, can improve the operating characteristics of the newborn screening program.