Richard M. Bergenstal, MD; Robin L. Gal, MSPH; Crystal G. Connor, MS, MPH; Rose Gubitosi-Klug, MD, PhD; Davida Kruger, MSN, APRN-BC, BC-ADM; Beth A. Olson, BAN, RN, CDE; Steven M. Willi, MD; Grazia Aleppo, MD; Ruth S. Weinstock, MD, PhD; Jamie Wood, MD; Michael Rickels, MD, MS; Linda A. DiMeglio, MD, MPH; Kathleen E. Bethin, MD, PhD; Santica Marcovina, PhD; Andreana Tassopoulos, BS; Sooji Lee, MS, MSPH; Elaine Massaro, MS; Suzan Bzdick, RN, CCRC; Brian Ichihara, BA; Eileen Markmann, BSN; Paul McGuigan, BSN; Stephanie Woerner; Michelle Ecker, RD, CDN, CDE; Roy W. Beck, MD, PhD; for the T1D Exchange Racial Differences Study Group *
Grant Support: By the Helmsley Charitable Trust (grant 2015PG-T1D033). A grant of no-charge materials was provided by Abbott Laboratories. Abbott Diabetes Care provided the continuous glucose monitors used in the study.
Disclosures: Dr. Bergenstal reports grants from and consulting/advisory board to Novo Nordisk, Abbott Diabetes Care, Becton Dickinson, Boehringer Ingelheim, Bristol-Myers Squibb/AstraZeneca, Calibra, Eli Lilly, Hygieia, Johnson & Johnson, Medtronic, Roche, Sanofi, Takeda, and DexCom during the conduct of the study and stock in Merck & Co. from a family inheritance outside the submitted work. Dr. Gubitosi-Klug reports that as a site investigator, she has an agreement with the Jaeb Center for Health Research (which organizes the Type 1 Diabetes Exchange) and received funds for recruitment of study participants. Ms. Kruger reports grants from Abbott during the conduct of the study and grants and personal fees from Abbott outside the submitted work. Dr. Willi reports that he serves on a data safety monitoring board for Caladrius and has a grant from Grifols outside the submitted work. Dr. Aleppo reports grants and personal fees from Novo Nordisk; personal fees from DEXCOM, Boehringer Ingelheim, and DIASEND; and grants from AstraZeneca outside the submitted work. Dr. Weinstock reports grants from Jaeb Center for Health Research and nonfinancial support from Abbott Diabetes Care during the conduct of the study, and grants from Medtronic MiniMed, Calibra Medical, Diasome Pharmaceuticals, and Mylan and nonfinancial support from DexCom outside the submitted work. Dr. Wood reports grants and nonfinancial support from Jaeb Center for Health Research/Helmsley Charitable Trust during the conduct of the study. Dr. Rickels reports grants from Jaeb Center for Health Research during the conduct of the study and personal fees from Janssen Research & Development, Semma Therapeutics, and Hua Medicine and nonfinancial support from Merck & Co. outside the submitted work. Dr. DiMeglio reports grants from Jaeb Center for Health Research during the conduct of the study and grants from Medtronic outside the submitted work. Dr. Bethin reports costs of performing the study from the Type 1 Diabetes Exchange during the conduct of the study and being a member of the pediatric diabetes and obesity advisory board and local principal investigator for drug trials and traveling to investigator meetings for Novo Nordisk; being the local principal investigator for a drug trial for Lexicon; and being the local principal investigator for drug trials and traveling to investigator meetings for Grifols, Debiopharm, and Locemia outside the submitted work. Ms. Bzdick reports grants from Jaeb Center for Health Research and nonfinancial support from Abbott Diabetes Care during the conduct of the study and grants from Medtronic MiniMed, Calibra Medical, and Diasome Pharmaceuticals outside the submitted work. Dr. Beck reports grants from Helmsley Charitable Trust and nonfinancial support from Abbott Diabetes Care during the conduct of the study and research grants to his institution and supplies for a study from Dexcom; a research grant to his institution from Animas, Bigfoot, and Tandem; and a consulting agreement with his institution by Lilly outside the submitted work. Authors not named here have disclosed no conflicts of interest. Forms can also be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M16-2596.
Editors' Disclosures: Christine Laine, MD, MPH, Editor in Chief, reports that she has no financial relationships or interests to disclose. Darren B. Taichman, MD, PhD, Executive Deputy Editor, reports that he has no financial relationships or interests to disclose. Cynthia D. Mulrow, MD, MSc, Senior Deputy Editor, reports that she has no relationships or interests to disclose. Deborah Cotton, MD, MPH, Deputy Editor, reports that she has no financial relationships or interest to disclose. Jaya K. Rao, MD, MHS, Deputy Editor, reports that she has stock holdings/options in Eli Lilly and Pfizer. Sankey V. Williams, MD, Deputy Editor, reports that he has no financial relationships or interests to disclose. Catharine B. Stack, PhD, MS, Deputy Editor for Statistics, reports that she has stock holdings in Pfizer and Johnson & Johnson.
Reproducible Research Statement:Study protocol: Available from Robin Gal (e-mail, rgal@jaeb.org). Statistical code: Not available. Data set: The data set will be posted at https://t1dexchange.org/pages/resources/clinic-network/studies/ once study group has completed planned primary and secondary analyses. Interim data requests can be sent to Robin Gal (e-mail, rgal@jaeb.org or t1dstats4@jaeb.org).
Requests for Single Reprints: Robin L. Gal, MSPH, Jaeb Center for Health Research, 15310 Amberly Drive, Suite 350, Tampa, FL 33647; e-mail, rgal@jaeb.org.
Current Author Addresses: Dr. Bergenstal and Ms. Olson: International Diabetes Center, 3800 Park Nicollet Boulevard, Minneapolis, MN 55416.
Ms. Gal, Ms. Connor, and Dr. Beck: Jaeb Center for Health Research, 15310 Amberly Drive, Suite 350, Tampa, FL 33647.
Dr. Gubitosi-Klug and Mr. McGuigan: University Hospitals of Cleveland, 11100 Euclid Avenue, Suite 737, Cleveland, OH 44106.
Ms. Kruger and Ms. Tassopoulos: Henry Ford Health System, 3031 West Grand Boulevard, Suite 800, Detroit, MI 48202.
Dr. Willi and Ms. Lee: Perelman School of Medicine, University of Pennsylvania, 3400 Civic Center Boulevard, Suite 11NW30, Philadelphia, PA 19104.
Dr. Aleppo and Ms. Massaro: Northwestern University, 675 North St. Claire Street, Suite 14-100, Chicago, IL 60611.
Dr. Weinstock and Ms. Bzdick: SUNY Upstate Medical University, 750 East Adams Street, CWB 353, Syracuse, NY 13210.
Dr. Wood and Mr. Ichihara: Children's Hospital of Los Angeles, 4650 Sunset Boulevard, Mail Stop 61, Los Angeles, CA 90027.
Dr. Rickels and Ms. Markmann: University of Pennsylvania Perelman School of Medicine, Rodebaugh Diabetes Center, 3400 Civic Center Boulevard, Building 421, 12th Floor, Philadelphia, PA 19104.
Dr. DiMeglio and Ms. Woerner: Indiana University School of Medicine, 702 Barnhill Drive, Room 5960, Indianapolis, IN 46202.
Dr. Bethin and Ms. Ecker: University at Buffalo Jacobs School of Medicine and Biomedical Sciences, 219 Bryant Street, Buffalo, NY 14222.
Dr. Marcovina: Northwest Lipid Metabolism and Diabetes Research Laboratories, 401 Queen Ann Avenue North, Seattle, WA 98109.
Author Contributions: Conception and design: R.M. Bergenstal, R.L. Gal, C.G. Connor, R.A. Gubitosi-Klug, S.M. Willi, M.R. Rickels, S. Woerner, R.W. Beck.
Analysis and interpretation of the data: R.M. Bergenstal, C.G. Connor, R.A. Gubitosi-Klug, B.A. Olson, G. Aleppo, J. Wood, M.R. Rickels, K. Bethin, S. Woerner.
Drafting of the article: R.M. Bergenstal, R.L. Gal, C.G. Connor, R.A. Gubitosi-Klug, K. Bethin, E.M. Massaro, S. Woerner, R.W. Beck.
Critical revision for important intellectual content: R.M. Bergenstal, R.L. Gal, C.G. Connor, R.A. Gubitosi-Klug, D.F. Kruger, B.A. Olson, S.M. Willi, G. Aleppo, R.S. Weinstock, J. Wood, M.R. Rickels, K. Bethin, S.M. Marcovina, R.W. Beck.
Final approval of the article: R.M. Bergenstal, R.L. Gal, C.G. Connor, R.A. Gubitosi-Klug, D.F. Kruger, B.A. Olson, S.M. Willi, G. Aleppo, R.S. Weinstock, J. Wood, M.R. Rickels, L. DiMeglio, K. Bethin, S.M. Marcovina, A.C. Tassopoulos, S. Lee, E.M. Massaro, S. Bzdick, B. Ichihara, E.M. Markmann, P. McGuigan, S. Woerner, M. Ecker, R.W. Beck.
Provision of study materials or patients: R.M. Bergenstal, R.A. Gubitosi-Klug, B.A. Olson, S.M. Willi, R.S. Weinstock, M.R. Rickels, K. Bethin, S.M. Marcovina, E.M. Massaro.
Statistical expertise: R.M. Bergenstal, C.G. Connor, R.W. Beck.
Obtaining of funding : R.L. Gal, R.W. Beck.
Administrative, technical, or logistic support: R.M. Bergenstal, R.L. Gal, M.R. Rickels, S. Bzdick, R.W. Beck.
Collection and assembly of data: R.M. Bergenstal, C.G. Connor, R.A. Gubitosi-Klug, D.F. Kruger, B.A. Olson, S.M. Willi, M.R. Rickels, K. Bethin, A.C. Tassopoulos, S. Bzdick, B. Ichihara, P. McGuigan.
Debate exists as to whether the higher hemoglobin A1c (HbA1c) levels observed in black persons than in white persons are due to worse glycemic control or racial differences in the glycation of hemoglobin.
To determine whether a racial difference exists in the relationship of mean glucose and HbA1c.
Prospective, 12-week observational study.
10 diabetes centers in the United States.
104 black persons and 104 white persons aged 8 years or older who had had type 1 diabetes for at least 2 years and had an HbA1c level of 6.0% to 12.0%.
Mean glucose concentration, measured by using continuous glucose monitoring and compared by race with HbA1c, glycated albumin, and fructosamine values.
The mean HbA1c level was 9.1% in black persons and 8.3% in white persons. For a given HbA1c level, the mean glucose concentration was significantly lower in black persons than in white persons (P = 0.013), which was reflected in mean HbA1c values in black persons being 0.4 percentage points (95% CI, 0.2 to 0.6 percentage points) higher than those in white persons for a given mean glucose concentration. In contrast, no significant racial differences were found in the relationship of glycated albumin and fructosamine levels with the mean glucose concentration (P > 0.20 for both comparisons).
There were too few participants with HbA1c levels less than 6.5% to generalize the results to such individuals.
On average, HbA1c levels overestimate the mean glucose concentration in black persons compared with white persons, possibly owing to racial differences in the glycation of hemoglobin. However, because race only partially explains the observed HbA1c differences between black persons and white persons, future research should focus on identifying and modifying barriers impeding improved glycemic control in black persons with diabetes.
Helmsley Charitable Trust.
Bergenstal RM, Gal RL, Connor CG, et al, for the T1D Exchange Racial Differences Study Group. Racial Differences in the Relationship of Glucose Concentrations and Hemoglobin A1c Levels. Ann Intern Med. 2017;167:95–102. [Epub ahead of print 13 June 2017]. doi: https://doi.org/10.7326/M16-2596
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© 2019
Published: Ann Intern Med. 2017;167(2):95-102.
DOI: 10.7326/M16-2596
Published at www.annals.org on 13 June 2017
Cardiology, Coronary Risk Factors, Diabetes, Endocrine and Metabolism.
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