Glucose harmonization: the role of accurate calibrators.
|Article Type:||Letter to the editor|
Glucose monitors (Health aspects)
|Publication:||Name: Archives of Pathology & Laboratory Medicine Publisher: College of American Pathologists Audience: Academic; Professional Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2009 College of American Pathologists ISSN: 1543-2165|
|Issue:||Date: Jan, 2009 Source Volume: 133 Source Issue: 1|
|Product:||Product Code: 3841315 Glucose Level Diagnostic Tests NAICS Code: 339112 Surgical and Medical Instrument Manufacturing SIC Code: 3845 Electromedical equipment|
|Geographic:||Geographic Scope: United States Geographic Code: 1USA United States|
To the Editor.--The article by Miller et al in the May issue of the
Archives of Pathology & Laboratory Medicine contains critical data
pertaining to the trueness of calibrators for glucose assays. 1 As shown
in their Figure 3, the mean concentration of glucose reported by 23 of
31 peer groups for sample C-02 was less than 1 mg/dL away from the
reference target, but 9 of the remaining peer groups reported mean
concentrations of glucose that were more than 2 mg/dL greater than
The deviant results are not surprising. During the past 10 years, my associates and I at Quest Diagnostics Inc (Madison, NJ) have detected 4 glucose calibrator problems upon receipt of new lots of calibrators. In each case, we changed the assigned glucose set point based on a rigorous internal validation protocol that uses NIST SRM (National Institute of Standards and Technology Standard Reference Materials) and the distribution of glucose concentrations of tens of thousands of patient samples. The deviation of vendor-assigned calibrator values from truth was always positive and ranged from +1.8% to +5.2%. Falsely assigned high values for calibrators lead to falsely high results for patient samples.
It is clear from the analysis of the survey data for C-02 that variation in glucose results is caused by variation from instrument type to instrument type and not by variation from reagent type to reagent type. The instrument to instrument variation is driven primarily by variation in the accuracy of the set points for the calibrators. The survey data and our experience point to the need for a program to harmonize glucose calibrators and patient results similar to that established for the National Glycohemoglobin Standardization Program. (2)
Finally, the need for tight control of glucose calibration is supported by the recent discovery that variation in fasting plasma glucose concentrations within the normal range is highly informative. (3)
RAYMOND GAMBINO, MD
Chief Medical Officer Emeritus
Deerfield Beach, FL 33442
(1.) Miller WG, Myers GL, Ashwood ER, et al. State of the art in trueness and interlaboratory harmonization for 10 analytes in general clinical chemistry. Arch Pathol Lab Med. 2008;132:838-846.
(2.) Little RR, Rohlfing CL,Wiedmeyer H-M, Myers GL, Sacks DB, Goldstein DE. The National Glycohemoglobin Standardization Program: a five-year progress report. Clin Chem. 2001;47:1985-1992.
(3.) Tirosh A, ShaiI I, Tekes-Manova D, et al. Normal fasting plasma glucose levels and type 2 diabetes in young men. N Engl J Med. 2005;353:1454-1462.
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