Evidence for Interindividual Heterogeneity in the Glucose Gradient Across the Human Red Blood Cell Membrane and Its Relationship to Hemoglobin Glycation

  1. Paramjit K. Khera1,
  2. Clinton H. Joiner2,
  3. Anthony Carruthers3,
  4. Christopher J. Lindsell4,
  5. Eric P. Smith1,
  6. Robert S. Franco5,
  7. Yancey R. Holmes1 and
  8. Robert M. Cohen16
  1. 1Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio
  2. 2Department of Pediatrics, Cincinnati Children's Hospital, Cincinnati, Ohio
  3. 3Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
  4. 4Division of Emergency Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio
  5. 5Division of Hematology and Oncology, Department of Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio
  6. 6Medical Service, Cincinnati Veterans Affairs Medical Center, Cincinnati, Ohio
  1. Corresponding author: Robert M. Cohen, robert.cohen{at}uc.edu

Abstract

OBJECTIVE—To determine whether interindividual heterogeneity in the erythrocyte (red blood cell [RBC]) transmembrane glucose gradient might explain discordances between A1C and glycemic control based on measured fructosamine.

RESEARCH DESIGN AND METHODS—We modeled the relationship between plasma glucose and RBC glucose as the concentration distribution (Ci-to-Co ratio) of a nonmetabolizable glucose analog 14C-3-O-methyl glucose (14C-3OMG) inside (Ci) and outside (Co) RBCs in vitro. We examined the relationship between that distribution and the degree of glycation of hemoglobin in comparison with glycation of serum proteins (fructosamine), the glycation gap. A1C, fructosamine, and in vitro determination of the 14C-3OMG distribution in glucose-depleted RBCs were measured in 26 fasted subjects.

RESULTS—The Ci-to-Co ratio 0.89 ± 0.07 for 3-O-methyl-d-glucopyranose (3OMG) ranged widely (0.72–1.04, n = 26). In contrast, urea Ci-to-Co (1.015 ± 0.022 [range 0.98–1.07], P < 0.0001) did not. Concerning mechanism, in a representative subset of subjects, the Ci-to-Co ratio was retained in RBC ghosts, was not dependent on ATP or external cations, and was reestablished after reversal of the glucose gradient. The 3OMG Ci-to-Co ratio was not correlated with serum fructosamine, suggesting that it was independent of mean plasma glucose. However, Ci-to-Co did correlate with A1C (R2 = 0.19) and with the glycation gap (R2 = 0.20), consistent with a model in which differences in internal glucose concentration at a given mean plasma glucose contribute to differences in A1C for given level of glycemic control.

CONCLUSIONS—The data demonstrate interindividual heterogeneity in glucose gradients across RBC membranes that may affect hemoglobin glycation and have implications for diabetes complications risk and risk assessment.

Footnotes

  • Published ahead of print at http://diabetes.diabetesjournals.org on 30 June 2008.

    Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.

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    • Accepted June 16, 2008.
    • Received December 25, 2007.
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  1. Diabetes vol. 57 no. 9 2445-2452
  1. All Versions of this Article:
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