Substantial attention has been paid to the global epidemic of diabetes among adults, but much less data are available for adolescents. Given the recent endorsement by the American Diabetes Association of glycated hemoglobin (HbA1c) for diabetes screening (1), a pilot HbA1c screening program was implemented in adolescent blood donors by Carter BloodCare, the largest independent blood program in Texas.
HbA1c was measured in 14,850 donors 16–19 years old during school blood drives conducted between 1 September 2011 and 30 April 2012. All donors gave informed consent. The main study measures were the prevalence of HbA1c levels in the prediabetes range (5.7–6.4%; 39–46 mmol/mol) and in the diabetes range (≥6.5%; ≥48 mmol/mol), with further stratification by sex, race/ethnicity, and sociodemographic characteristics.
The cohort included 48.7% girls, 54.7% whites, 3.5% blacks, 24.6% Hispanics, 2.3% Asians, and 15% participants of other/unknown race/ethnicity. Table 1 presents cohort characteristics stratified by HbA1c category. The HbA1c level was above the diabetes threshold in 94 donors (0.6%), and in the prediabetes range in 1,479 donors (10%).
Sociodemographic characteristics and selected cardiovascular risk factors of the study population stratified by HbA1c categories
There were no significant age differences across HbA1c categories (Ptrend = 0.52), but a larger proportion of boys versus girls (16.5 vs. 5.0%, P < 0.001) had HbA1c levels ≥5.7% (including both the prediabetic and the diabetic range). There were also marked differences in the prevalence of HbA1c levels ≥5.7% across race/ethnic groups, with over-representation of blacks and Asians in the elevated HbA1c groups (Table 1). The HbA1c level was ≥5.7% in 53.4% of blacks, 20.9% of Asians, 10.7% of Hispanics, and 7.5% of whites (P < 0.001 for whites vs. every other race/ethnic group). In analyses stratified by sex and race/ethnicity, boys remained more likely than girls to have an HbA1c level ≥5.7% within each race/ethnicity group (P < 0.001 for each). In analyses of cardiovascular risk factors stratified by HbA1c categories, higher total cholesterol levels and diastolic blood pressure were observed across categories of increasing HbA1c (Table 1). Although secure online access to test results was provided to all donors, only 11% retrieved their HbA1c results.
Limitations of this study include the absence of repeat/confirmatory testing for those with abnormal HbA1c, and the fact that HbA1c thresholds established for adults have lower sensitivity for the detection of prediabetes and diabetes in adolescents (2), likely leading to an underestimation of the prevalence of these conditions in our cohort. However, the overall prevalence of HbA1c levels of 5.7–6.4% in our study was comparable to the prevalence of prediabetes by fasting glucose and/or oral glucose tolerance testing in 16- to 19-year-old participants in the National Health and Nutrition Examination Survey 2005–2006 (3). The prevalence of HbA1c levels ≥6.5% in our cohort was almost twofold higher than the estimated prevalence of diagnosed diabetes in U.S. youth (4), possibly reflecting a high prevalence of undiagnosed diabetes.
This pilot program demonstrates the feasibility of leveraging the community blood donation program as a unique and highly efficient portal for early health screening, with potential for public health intervention. With increased HbA1c levels in U.S. adolescents and young adults recently associated with a higher risk of premature (<55 years of age) death (5), early screening and intervention is more important than ever.
Article Information
Funding. M.O.G. was supported by cardiology fellowship training grant T32HL007360 from the National Heart, Lung, and Blood Institute of the National Institutes of Health (NIH). Carter BloodCare supported all sample collection and cholesterol testing. HbA1c testing was funded by the Carter BloodCare Foundation, the Lange Endowment Disbursement Fund #2 of Communities Foundation of Texas, and Coca-Cola Enterprises. The sponsors had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.
Duality of Interest. S.J.E. and M.S. are employed by, but have no equity interests in, Carter BloodCare. J.A.d.L. received speaker honoraria from AstraZeneca and Bristol-Myers Squibb and grant support from Roche Diagnostics and Abbott Diagnostics not related to diabetes. D.K.M. was a consultant for Janssen, Boehringer Ingelheim, Daiichi Sankyo, Genentech, Roche, Merck, Eli Lilly, Bristol-Myers Squibb, AstraZeneca, and Takeda. No other potential conflicts of interest relevant to this article were reported.
Author Contributions. M.O.G. analyzed and interpreted the data, critically revised the manuscript for important intellectual content, and drafted the manuscript. S.J.E. and M.S. acquired the data, analyzed and interpreted the data, critically revised the manuscript for important intellectual content, and were responsible for the study concept and design. C.R.A. performed the statistical analysis, analyzed and interpreted the data, and critically revised the manuscript for important intellectual content. A.T. and A.K. analyzed and interpreted the data and critically revised the manuscript for important intellectual content. J.A.d.L. and D.K.M. analyzed and interpreted the data, critically revised the manuscript for important intellectual content, drafted the manuscript, and were responsible for the study concept and design. D.K.M. is the guarantor of this work and, as such, had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
