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Translating the Hemoglobin A1C with More Easily Understood Feedback: A Randomized Controlled Trial



Previous work has indicated that for patients with diabetes, there is value in understanding glycemic control. Despite these findings, patient understanding of the hemoglobin A1C value (A1C) is notably poor. In this study, we test the effect of two alternative communication formats of the A1C on improving glycemic control among patients with poorly controlled diabetes.


177 patients with poorly controlled diabetes were randomized to one of three study arms that varied in the information they received: (1) a “diabetes report card” containing individualized information about glycemic control for each participant with letter grades ranging from A to F; (2) a “report card” containing a face whose emotion reflected current glycemic control; or (3) a “report card” with glycemic control expressed with the A1C value (standard arm). The primary study outcome was change in A1C at 6 months. Secondary outcomes included changes in participant perceptions of their glycemic control.


The average A1C for enrolled participants was 9.9 % (S.D. 1.7) and did not differ significantly among study arms. We noted no significant differences in change in A1C at 6 months between the standard and experimental arms. Using multiple imputation to account for missing A1C values, the changes in A1C for the letter grade, face, and standard arms were -0.55 % (-1.15, 0.05), -0.89 % (-1.49, -0.29), and -0.74 % (-1.51, 0.029), respectively (p = 0.67 for control vs. grade, p = 0.76 for control vs. face).


Feedback to patients with poorly controlled diabetes in the form of letter grades and faces did not differentially impact glycemic control at 6 months or participant perceptions of current control. These efforts to improve communication and patient understanding of disease management targets need further refinement to significantly impact diabetes outcomes.

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All authors listed on the title page met the criterion for authorship based on the Committee on Publication Ethics guidelines.


Cathy Bryan assisted with participant recruitment and enrollment, Dr. Mark Wiener, and Alice Livshits assisted with use of the E.M.R. and tracking of participant outcomes, and Yuanyuan Tao helped with exploratory data analysis.


Penn CMU Roybal P30 Center Grant P30AG034546. The funder was not involved in any part of the study design, conducting of the study or the analysis of the results.

Prior Presentations

This work was presented as an oral abstract at the 2013 Society of General Internal Medicine Annual Meeting.

Competing Interests

Several members of the research team and the submitted work were supported by grant funds from the Penn CMU Roybal P30, a non-profit entity; no member of the research team had any financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years; there are no other relationships or activities that may have otherwise influenced the submitted work.

Ethical Approval

The study protocol was approved by the University of Pennsylvania Institutional Review Board.

Data Sharing

No additional data available.

Peer Review

Not commissioned, externally peer-reviewed.

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Correspondence to Anjali Gopalan M.D..

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Gopalan, A., Tahirovic, E., Moss, H. et al. Translating the Hemoglobin A1C with More Easily Understood Feedback: A Randomized Controlled Trial. J GEN INTERN MED 29, 996–1003 (2014).

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  • diabetes
  • hemoglobin A1C
  • communication
  • health literacy
  • diabetes education