Whole-Blood Glucose Testing at Alternate Sites

Abstract

ALTHEA ANAGNOSTOPOULOS, MS 2OBJECTIVE -To measure hematocrit (Hct) and glucose concentration in capillary blood drawn from the fingertip and forearm of a group of 50 nonfasting subjects with diabetes. RESEARCH DESIGN AND METHODS -Hct was determined indirectly by measuringHb with the HemoCue B-Hemoglobin Photometer. Glucose was assayed with the HemoCue B-Glucose Analyzer, chosen as the independent control assay, and the Sof-Tact Blood Glucose System. Testing session with each subject lasted ϳ30 min and consisted of a sequence of tests with each device (SofTact, HemoCue Glucose, and HemoCue Hemoglobin), performed on the arm and then on the fingertip. This sequence was performed three times, so all tests were done in triplicate. Additional fingersticks were performed on each subject at the start and end of the session to measure net change of glucose status during the experiment with a YSI Glucose Analyzer. The mean of the triplicate assays was used to calculate each subject's percent of glucose difference between arm and finger [(arm glucose Ϫ finger glucose)/finger glucose]. Because of the order in which replicates were performed, time-dependent changes in the glucose status of subjects had little effect on the mean values. Thus, the percent of glucose difference calculated herein reflects the intrinsic difference between forearm and fingertip.RESULTS -Hb concentration and Hct were found to be significantly higher in the arm than in the finger. When intraperson differences were calculated, the difference for Hb and Hct was found to be 1.8 Ϯ 1.1 g/dl (mean Ϯ SD) and 5.3 Ϯ 3.0%, respectively. In contrast to Hb, the percent of glucose difference between arm and finger was statistically insignificant. When measured with HemoCue, the percent of glucose difference was Ϫ0.1 Ϯ 8% for all 50 subjects, Ϫ1 Ϯ 6% for 20 subjects, for whom blood glucose varied Ͻ9 mg/dl during the experiment, and 2 Ϯ 10% for 15 subjects, for whom blood glucose varied Ͼ18 mg/dl. Thus, irrespective of how much blood glucose changed among the subjects, the glucose difference between forearm and fingertip was insignificant and less than measurement errors. A major source of error in the calculated differences was variability between replicates. No correlation was observed between an individual's Hct bias and his or her percent of glucose difference, as measured with HemoCue. The results with Sof-Tact were similar, with percent of glucose difference again being statistically insignificant. The measured difference was Ϫ4 Ϯ 13% for all 50 subjects, Ϫ1 Ϯ 15% for 20 subjects, for whom blood glucose varied Ͻ9 mg/dl during the experiment, and Ϫ1 Ϯ 12% for 15 subjects, for whom blood glucose varied Ͼ18 mg/dl. There was no correlation between a subject's Hct bias and his or her glucose difference, as measured with Sof-Tact.CONCLUSIONS -In this cross-sectional study of 50 nonfasting subjects whose blood glucose concentration changed to various degrees during the experiment, no significant glucose difference was observed between the capillary beds of the fore...

Comparison of Blood Glucose Measurements Using Samples Obtained from the Forearm, Finger Skin Puncture, and Venous Serum

“…The difference between the whole-blood glucose levels obtained by capillary blood sampling from the forearm and from the finger was reported to be statistically insignificant, but that assessment was performed in a limited number of subjects [16]. However, clinical practice usually requires additional validation in a sufficiently large subject population as well as over a wide range of glucose concentrations, and these requirements served as the motivations for the present study.…”

“…Furthermore, the intraclass correlation coefficient values were statistically highly significant (P<0.0001), thereby indicating that GA correlated well with both GF and GV. Similar values between these 2 different types of correlation coefficient not only imply insignificant difference in the measurement characteristics between the groups but also reflect that no significant error was introduced in our experiment, thereby satisfying the pre-requisite of the simple linear regression analysis usually performed in glucose measurement [14,16] as per the FDA recommendations for approval [19].…”

“…The BGT results obtained for the forearm showed no significant differences to those for the finger in 50 nonfasting subjects [16]. However, a large-scale clinical study encompassing a wide range of glucose levels should precede the introduction of this new capillary blood sampling technique into clinical practice.…”

Correlation of the Blood Test Results Obtained between Assays Using Microliter-scale Fingertip Blood Samples Collected with a Novel Blood Collection Device and Conventional Venous Blood Assays: a Secondary Publication in English

“…Moreover, for blood glucose, no significant difference was observed between the fingertip and venous blood assays in this study, which is consistent with a previous report. 2 In the blood cell count measurement, we reviewed the procedures and were able to successfully prevent coagulation of the specimens by thoroughly mixing the contents by snap-shaking after the fingertip blood collection. Yang, et al 1 reported a difference in the WBC count between fingertip blood and venous blood, and also that by repeated collection there was a decrease in the WBC count in fingertip blood.…”

“…[1][2][3][4][5] For example, correlations between assay results using blood samples collected from a vein, such as the ante-cubital vein (hereinafter referred to as "venous blood"), and fingertip blood samples have been reported for biochemical tests. 4 In addition, it has been suggested that hematological tests can be also measured in fingertip blood samples as long as test values are within the reference intervals established by the Japanese Committee for Clinical Laboratory Standards and if the following two conditions are met: capillary-collected blood is promptly transferred into a microliter-scale blood collection tube containing ethylenediaminetetraacetic acid (EDTA) and contamination with interstitial fluid by forced blood extrusion is avoided.…”