Use of HbA1c in the Diagnosis of Diabetes in Adolescents

2014 Archives, Archives, Diabetes, July 2014, Vol. 21, No. 7, Outcomes Research in Review

Lee JM, Eason A, Nelson C, et al. Screening practices for identifying type 2 diabetes in adolescents. J Adolesc Health 2014;54:139–43.

 

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Study Overview

Objective. To examine the screening practices of family practitioners (FPs) and pediatricians for type 2 diabetes (T2D) in adolescents.

Design. Cross-sectional study.

Setting and participants. The researchers randomly sampled 700 pediatricians and 700 FPs who participated in direct patient care using the American Medical Association Physician Masterfile using a mail survey. Exclusion criteria included providers who were residents, hospital staff, retirees, or employed by federally owned medical facilities, certified with a subspecialty, or over age 70.

Main outcome measures. Providers were given a hypothetical case of an obese, female, teenaged patient with concurrent associated risk factors for T2D (family history of T2D, minority race, signs of insulin resistance) and asked what initial screening tests they would order. Respondents were then informed of the updated American Diabetes Association (ADA) guidelines that added hemoglobin A1c as a screening test to diagnose diabetes. The survey then asked if knowing this change in recommendation has changed or will change their screening practices in adolescents.

Main results. 1400 surveys were mailed. After 2 were excluded due to mailing issues, 52% of providers provided responses. Of these, 129 providers reported that they did not care for adolescents (age 10–17), resulting in 604 providers in the final sample, 398 pediatricians and 335 FPs.

The vast majority (92%) said they would screen the hypothetical case for diabetes, with most initially ordering a fasting test (fasting plasma glucose or 2-hour glucose tolerance test) (63%) or A1c test (58%). Of the 58% who planned to order HbA1c, only 35% ordered it in combination with a fasting test. HbA1c was significantly more likely to be ordered by pediatricians than by FPs (P = 0.001). After being presented with the new guidelines, 84% said then would now order HbA1c, a 27% increase.

Conclusion. In response to information about the new guidelines, providers were more likely to order A1c as part of initial testing. Due to the lower test performance in children and increased cost of the test, the use of HbA1c without fasting tests may result in missed diagnosis of T2D in adolescents as well as increased health care costs.

 

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Commentary

Rates of childhood obesity continue to rise throughout the United States. Obese children are at risk for numerous comorbidities such as hypertension, hyperlipidemia, and T2D [1,2]. It is important for providers to use effective screening tools for risk assessment of prediabetes/T2DM in children.

The standard tests for diagnosing diabetes are the fasting plasma glucose test and the 2-hour plasma glucose test. While accurate, these tests are not convenient. In 2010, the ADA added an easier method of testing for T2D: an HbA1c, with results greater than or equal to 6.5% indicating diabetes [3]. However, this recommendation is controversial, given studies suggesting that HbA1c is not as reliable in children as it is in adults [4–6]. The ADA itself acknowledges that there are limited data in the pediatric population.

In this study, most providers were unaware of the 4-year-old revised guidelines offering the A1c option but are planning to apply the guidelines going forward. According to the study, this would result in a 27% increase in providers utilizing HbA1c.

Should increased uptake of A1c as an initial screening test be a concern? Using it in combination with other tests may be useful for assessing which adolescents will need further testing [3–6]. Additionally, by starting with a test that can be performed in the office with no regard to fasting time, it is possible that more cases of T2D will be found by primary care providers treating adolescents.

A weakness of the study is the potential for response bias related to mailed surveys. An additional weakness is that the researchers utilized only 1 hypothetical situation. Providing additional hypothetical situations may have allowed for further understanding of screening practices. The investigators also did not include nurse practitioners or physician assistants in their sample, a growing percentage of whom may care for adolescent populations at risk for T2D or be primary referral sources.

 

Applications for Clinical Practice

Providers can use HbA1c to screen for diabetes in nonfasting adolescents at risk for diabetes. While the test may not be as accurate in pediatric patients, utilizing HbA1C as directed by the ADA may aid in diagnosing patients that may otherwise miss follow-up appointments to complete a fasting test.

—Jennifer L. Nahum, MSN, CPNP-AC, PPCNP-BC, and Allison Squires, PhD, RN

References

1. Freedman DS, Dietz WH, Srinivasan SR, Berenson GS. The relation of overweight to cardiovascular risk factors among children and adolescents: the Bogalusa Heart Study. Pediatrics 1999;103(6 Pt 1):1175–82.

2. Pinhas-Hamiel O, Dolan LM, Daniels SR, Standiford D, Khoury PR, Zeitler P. Increased incidence of non-insulin-dependent diabetes mellitus among adolescents. J Pediatr 1996;128(5 Pt 1):608–15.

3. American Diabetes Association. Type 2 diabetes in children and adolescents. Pediatrics 2000 Mar;105(3 Pt 1):671–80.

4. Lee JM, Gebremariam A, Wu EL, et al. Evaluation of nonfasting tests to screen for childhood and adolescent dysglycemia. Diabetes Care 2011;34:2597–602.

5. Nowicka P, Santoro N, Liu H, et al. Utility of hemoglobin A(1c) for diagnosing prediabetes and diabetes in obese children and adolescents. Diabetes Care 2011;34:1306–11.

6. Lee JM, Wu EL, Tarini B, et al Diagnosis of diabetes using hemoglobin A1c: should recommendations in adults be extrapolated to adolescents? J Pediatr 2011;158:947–952.

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