Intensive Care Medicine

, Volume 33, Issue 12, pp 2079–2084

Accuracy of bedside capillary blood glucose measurements in critically ill patients

  • C. Dana Critchell
  • Vincent Savarese
  • Amy Callahan
  • Christine Aboud
  • Serge Jabbour
  • Paul Marik



To compare the accuracy of fingerstick with laboratory venous plasma glucose measurements (laboratory glucose) in medical ICU patients and to determine the factors which interfere with the accuracy of fingerstick measurements.


The study included 80 consecutive patients aged 58 ± 7 years, BMI 29.5 ± 9.0, and APACHE II score 15 ± 6 (277 simultaneous paired measurements).


This prospective observational study compared fingerstick measurements to simultaneously sampled laboratory glucose once a day in patients in our medical ICU (twice daily if on an insulin infusion). Data recorded included patient demographics, admission diagnoses, APACHE II score, BMI, daily hematocrit, arterial blood gasses, chemistry results, concomitant medications (including vasopressors and corticosteroids), and upper extremity edema. Accuracy was defined as the percentage of paired values not in accord (> 15 mg dl–1 / 0.83 mmol–1 l–1 difference for laboratory values < 75 mg dl–1 / 4.12 mmol–1 l–1 and > 20% difference for laboratory values ≥ 75 mg/dl). Outliers (blood glucose difference > 100 mg dl–1 / 5.56 mmol–1 l–1) were excluded from the correlation and distribution analyses.


Mean fingerstick glucose was 129 ± 45 mg/dl (7.2 ± 2.5 mmol/l) and mean laboratory glucose 123 ± 44 mg/dl (6.8 ± 2.4 mmol/l). The correlation coefficient between the two values was 0.9110 (Clinical and Laboratory Standards Institute threshold 0.9751). The mean difference (bias) between the two methods was 8.6 ± 18.6 mg/dl (0.48 ± 1.0 mmol/l) and limits of agreement +45.8 and –28.6 mg/dl (+2.5 and –1.6 mmol/l). Fifty-three (19%) paired measurements in 22 patients were not in accord (CLSI threshold ≤ 5%). In 44 (83%) of these paired measurements fingerstick glucose was greater than laboratory glucose.


The findings suggest that capillary blood glucose as measured by fingerstick is inaccurate in critically ill ICU patients and does not meet the CLSI standard. It is unclear whether the sampling method, device used, or both contributed to this inaccuracy. The wide limits of agreement suggest that fingerstick measurements should be used with great caution in protocols of tight glycemic control.


Glucose Point-of-care testing Capillary blood Intensive care unit critically ill Sepsis Fingerstick 


  1. 1.
    van den Berghe G, Wouters P, Weekers F, Verwaest C, Bruyninckx F, Schetz M, Vlasselaers D, Ferdinande P, Lauwers P, Bouillon R (2001) Intensive insulin therapy in critically ill patients. N Engl J Med 345:1359–1367CrossRefGoogle Scholar
  2. 2.
    Kanji S, Buffie J, Hutton B, Bunting PS, Singh A, McDonald K, Fergusson D, McIntyre LA, Hebert PC (2005) Reliability of point-of-care testing for glucose measurement in critically ill adults. Crit Care Med 33:2778–2785PubMedCrossRefGoogle Scholar
  3. 3.
    Chakravarthy SB, Markewitz BA, Lehman C, Orme JF (2005) Accuracy of glucose measurements in critically ill patients in shock (abstract). Chest 128:220SGoogle Scholar
  4. 4.
    Finkielman JD, Oyen LJ, Afessa B (2005) Agreement between bedside blood and plasma glucose measurement in the ICU setting. Chest 127:1749–1751PubMedCrossRefGoogle Scholar
  5. 5.
    Kulkarni A, Saxena M, Price G, O'Leary MJ, Jacques T, Myburgh JA (2005) Analysis of blood glucose measurements using capillary and arterial blood samples in intensive care patients. Intensive Care Med 31:142–145PubMedCrossRefGoogle Scholar
  6. 6.
    Vriesendorp TM, van Santen S, DeVries JH, de Jonge E, Rosendaal FR, Schultz MJ, Hoekstra JB (2006) Predisposing factors for hypoglycemia in the intensive care unit. Crit Care Med 34:96–101PubMedCrossRefGoogle Scholar
  7. 7.
    van den Berghe G, Wilmer A, Hermans G, Meersseman W, Wouters PJ, Milants I, van Wijngaerden E, Bobbaers H, Bouillon R (2006) Intensive insulin therapy in the medical ICU. N Engl J Med 354:449–461CrossRefGoogle Scholar
  8. 8.
    Critchell C, Callahan A, Aboud C, Jabbour S, Marik PE (2006) Accuracy of bedside capillary blood glucose measurements in critically ill patients (abstract). Crit Care Med 34(Suppl A):68CrossRefGoogle Scholar
  9. 9.
    Marik PE, Varon J (2007) Intensive insulin therapy in the ICU: is it now time to jump off the bandwagon? Resuscitation 2007:191–193CrossRefGoogle Scholar
  10. 10.
    Knaus WA, Draper EA, Wagner DP, Zimmerman JE (1985) APACHE II: a severity of disease classification system. Crit Care Med 13:818–828PubMedCrossRefGoogle Scholar
  11. 11.
    Szczesny G, Olszewski WL (2003) The pathomechanism of posttraumatic edema of the lower limbs. II. Changes in the lymphatic system. J Trauma 55:350–354PubMedCrossRefGoogle Scholar
  12. 12.
    Bland JM, Altman DG (1986) Statistical methods for assessing agreement between two methods of clinical measurement. Lancet I:307–310Google Scholar
  13. 13.
    Atkin SH, Dasmahapatra A, Jaker MA, Chorost MI, Reddy S (1991) Fingerstick glucose determination in shock. Ann Intern Med 114:1020–1024PubMedGoogle Scholar
  14. 14.
    Sylvain HF, Pokorny ME, English SM, Benson NH, Whitley TW, Ferenczy CJ, Harrison JG (1995) Accuracy of fingerstick glucose values in shock patients. Am J Crit Care 4:44–48PubMedGoogle Scholar
  15. 15.
    Brunkhorst FM, Wahl HG (2006) Blood glucose measurements in the critically ill: more than just a blood draw. Crit Care 10:178PubMedCrossRefGoogle Scholar
  16. 16.
    Wiener K (1995) Whole blood glucose: what are we actually measuring? Ann Clin Biochem 32:1–8PubMedGoogle Scholar
  17. 17.
    Sidebottom RA, Williams PR, Kanarek KS (1982) Glucose determinations in plasma and serum: potential error related to increased hematocrit. Clin Chem 28:190–192PubMedGoogle Scholar
  18. 18.
    Fogh-Anderson N, D'Orazio P (1998) Proposal for standardizing direct-reading biosensors for blood glucose. Clin Chem 44:655–659Google Scholar
  19. 19.
    Sazama K, Robertson EA, Chesler RA (1979) Is antiglycolysis required for routine glucose analysis? Clin Chem 25:2038–2039PubMedGoogle Scholar
  20. 20.
    Tang Z, Louie RF, Lee JH, Lee DM, Miller EE, Kost GJ (2001) Oxygen effects on glucose meter measurements with glucose dehydrogenase- and oxidase-based test strips for point-of-care testing. Crit Care Med 29:1062–1070PubMedCrossRefGoogle Scholar
  21. 21.
    Tang Z, Du X, Louie RF, Kost GJ (2000) Effects of drugs on glucose measurements with handheld glucose meters and a portable glucose analyzer. Am J Clin Pathol 113:75–86PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • C. Dana Critchell
    • 1
  • Vincent Savarese
    • 1
  • Amy Callahan
    • 2
  • Christine Aboud
    • 2
  • Serge Jabbour
    • 1
    • 3
  • Paul Marik
    • 1
    • 4
  1. 1.Department of MedicineThomas Jefferson UniversityPhiladelphiaUSA
  2. 2.Department of NursingThomas Jefferson University HospitalPhiladelphiaUSA
  3. 3.Division of EndocrinologyThomas Jefferson UniversityPhiladelphiaUSA
  4. 4.Division of Pulmonary and Critical Care MedicineThomas Jefferson UniversityPhiladelphiaUSA

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