Clinical Chemistry Link to Randox Laboratories Web Site
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Clinical Chemistry 47: 1212-1217, 2001;
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit an electronic Letter to
the Editor about this paper
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (6)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Skeie, S.
Right arrow Articles by Sandberg, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Skeie, S.
Right arrow Articles by Sandberg, S.
Related Collections
Right arrow Evidence Based Laboratory Medicine and Test Utilization
Right arrow Endocrinology and Metabolism
(Clinical Chemistry. 2001;47:1212-1217.)
© 2001 American Association for Clinical Chemistry, Inc.

Articles

Interpretation of Hemoglobin A1c (HbA1c) Values among Diabetic Patients

Implications for Quality Specifications for HbA1c

Svein Skeie1a, Geir Thue1 and Sverre Sandberg1

1 NOKLUS, Norwegian Center for External Quality Improvement of Primary Care Laboratories, Division of General Practice, Department of Public Health and Primary Care, Ulriksdal 8c, University of Bergen, N-5009 Bergen, Norway.


aAddress correspondence to this author at: Department of Medicine, Rogaland Central Hospital, PO Box 8100, 4068 Stavanger, Norway. Fax 47-51-51-99-06; e-mail svskeie{at}online.no


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Background: Few studies have examined patients’ views, knowledge, and understanding of glycohemoglobin A1c (HbA1c) testing. We explored such issues in patients with type 1 diabetes and used their statements to estimate analytical quality specifications for HbA1c testing.

Methods: We recruited 201 patients from a hospital outpatient clinic. A questionnaire was used to collect information on diabetes characteristics, perceived knowledge of HbA1c, last HbA1c value, HbA1c target value, and thresholds for action. Patients were asked to indicate the magnitude of change in HbA1c from 9.4% that they would consider to be a true (real) change; from their responses, we calculated patient-derived quality specifications for HbA1c.

Results: Fifty-eight percent of the patients felt they had "high" knowledge about HbA1c, and >80% of responders knew their last HbA1c value, their target HbA1c, and the threshold value of HbA1c for treatment intensification. The mean acceptable HbA1c value was 7.5%. Patients with lower values on their most recent tests reported lower target values for HbA1c and lower values for the upper HbA1c threshold for treatment intensification. An analytical CV (CVa) of 3.1% would be satisfactory for 75% of patients when HbA1c is increasing (80% confidence), and a CVa of 3.2% would be satisfactory for 75% when HbA1c is decreasing (95% confidence).

Conclusions: Type 1 patients’ perceived knowledge about HbA1c testing is high. They are well informed about their own personal results and about target values and the upper HbA1c threshold for action. The patient-derived analytical quality specification for imprecision (CV) is 3.1%.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
The relationships between glycohemoglobin A1c (HbA1c)1 1 and blood glucose concentrations and late complications have been established over the last 30 years (1)(2)(3)(4)(5)(6)(7). HbA1c measurements have become routine practice, and it has been shown that long-term regular measurement of HbA1c leads to improved metabolic control (8).

In a previous study, we examined the use and interpretation of results from glucose self-measurements among diabetic patients (9)(10). A similar study of HbA1c would be more complicated because the patients do not perform the analysis themselves. Nonetheless, because HbA1c has become the most important way of measuring long-term metabolic control, diabetes caregivers and patients need a similar understanding and interpretation of HbA1c values and what should be considered "real" changes in HbA1c. Today, patients’ knowledge about diabetes and HbA1c comes not only from caregivers, but increasingly from other sources such as diabetes associations, diabetes magazines, and sites on the World Wide Web. The use and interpretation of HbA1c results among physicians (11)(12) have been studied, but there is a lack of studies of patients’ views, knowledge, and understanding of HbA1c testing. Consequently, this study was designed to explore these aspects among type 1 diabetes patients and to use their statements concerning changes in HbA1c to define patient-derived analytical quality specifications for the HbA1c analysis.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Patients with type 1 diabetes mellitus were recruited from March to November 1998. Consecutive individuals were included at their scheduled follow-up visit with an endocrinologist or a diabetes nurse at the diabetes outpatient clinic, Rogaland Central Hospital (Stavanger, Norway). In our clinic, like most clinics for diabetic patients, virtually every patient with type 1 diabetes performs self-monitoring of blood glucose (SMBG). All follow-up visits usually include a HbA1c measurement performed in the hospital central laboratory, where the upper reference limit for HbA1c is 5.9%. HbA1c is measured on a Diamat HPLC (Bio-Rad Laboratories), and the values obtained are traceable to the "DCCT method". Performance is controlled by internal quality controls as well as by participation in an external quality control scheme where the target values are determined with the DCCT method. Most of the studied patients attend the clinic as their primary location for diabetes care. Over the past 10 years, it has been a clinical practice goal to measure HbA1c every 3 months and to inform patients about the results, as recommended by the American Diabetes Association (13). Generally, newly diagnosed patients in Norway are, as in our clinic, informed and educated about what HbA1c is and what the short- and long-term consequences of different degrees of metabolic control might be. On the basis of established recommendations, it is the policy to discuss and to set individual HbA1c targets together with the patient (7)(13)(14).

The present study is based on self-reported data obtained with a questionnaire developed in cooperation with a diabetes specialist, diabetes nurses, and patients with type 1 diabetes. The questionnaire was evaluated by 10 type 1 patients in a pilot study before recruitment for the larger study was initiated, and only minimal changes were made. Assisting personnel handed the questionnaire to the patients when they arrived; patients answered the questions without assistance or professional influence before consultation with the nurse/doctor. Responders sealed their questionnaires in envelopes and placed them in a box, but because the questionnaires were anonymous, routines were established to ensure that no patient was included more than once.

In the general part of the questionnaire, patients stated their age, sex, and year that their diabetes was diagnosed as well as how long and how frequently they had performed SMBG. We then assessed patients’ perceived general knowledge about the HbA1c test, whether they knew their last HbA1c result, their target HbA1c value, and the upper and lower thresholds for treatment changes (Fig. 1 ). The questionnaire included an opportunity to respond "Don’t remember" or "Don’t know" to these questions, which probably increased the likelihood of true and correct responses.



View larger version (31K):
[in this window]
[in a new window]
  		Figure 1. Questionnaire on HbA1c.

The two last questions assessed the magnitude of change in HbA1c from 9.4% necessary for patient to be certain that the change indicated a true (real) improvement or deterioration of their diabetes, i.e., the so-called critical difference (CD). The 9.4% value was chosen based on experience from a comparable study and our pilot test, both of which indicated that patients felt that they could foresee both improvement and deterioration of their metabolic control when this value was used as baseline (12).

The CD is conventionally defined as the difference needed between two consecutive test values to be certain (with a given probability) that the two results actually are different (i.e., that the change is not caused by analytical and biological variation). The formula used is: CD = bias + z value x x (15). We used z values for one-sided tests and 95% or 80% probabilities (z values of 1.64 and 0.84, respectively) to reflect the participants’ certainty before initiating an action. CVa is an estimate of the analytical imprecision (16), and CVi is the mean within-subject CV for HbA1c (16). Calculations were performed using this formula with a CVi of 4% (17). Patients’ responses concerning the magnitude of change in HbA1c from 9.4% that they considered to be a true (real) change were taken as the CD. We then rearranged the formula to calculate the CVa, which can be considered the quality goal for imprecision, assuming the bias component to be zero (9)(12)(18).

The Student t-test or nonparametric tests were used when appropriate. Correlation coefficients were calculated using the Pearson method. Statistical significance was set at 5%.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
A total of 201 patients with type 1 diabetes were enrolled in the study, and none refused to participate. Most patients had been diagnosed with diabetes >14 years prior to the study. Patient characteristics are given in Table 1 . Six patients performed SMBG less than once per week (SMBG frequency = 0), and seven patients were diagnosed with diabetes and had initiated SMBG within the last year (diabetes and SMBG duration = 0). The women were older with longer duration of diabetes and performed SMBG more frequently than the men (P <0.05). For all other questions on the questionnaire, no differences were seen in responses between men and women, and thus combined results are presented.


View this table:
[in this window]
[in a new window]
  		Table 1. Patient characteristics (n = 201).1

Question 1 assessed patients’ perceived knowledge about HbA1c testing (Fig. 1Up ). Fifty-eight percent responded that they had "high" knowledge of HbA1c testing [categories "very good" (18%) or "sufficient" (40%)], whereas 42% thought they had "low" knowledge [categories "some" (30%), "little" (10%), or "no" (2%)]. The two groups did not differ with regard to age, sex, or SMBG frequency. Patients in the high-knowledge group had a longer duration of diabetes (16.2 vs 12.7 years; P = 0.025) and had performed SMBG longer (10.8 vs 8.6 years; P = 0.012) than those in the low-knowledge group.

Questions 2–5 assessed personal HbA1c values, target values, and thresholds for action (Table 2 ). Response rates were lower on these questions, varying from 70% on question 5 to 90% on question 3. Five percent of patients responded that they did not know their own HbA1c target (question 3), whereas 18% reported that they did not know their lower HbA1c threshold for action (question 5). Patients who had a low HbA1c value at their last visit also reported lower HbA1c satisfactory values (r = 0.436; P <0.01) and lower upper thresholds for treatment intensification (r = 0.631; P <0.01). There was no significant difference in responses concerning HbA1c values on these four questions between the two groups with different knowledge levels, but patients in the low-knowledge group had significantly lower response rates on these four questions compared with the high-knowledge group (mean, 72% vs 90%; P <0.05).


View this table:
[in this window]
[in a new window]
  		Table 2. Patient responses to different questions concerning HbA1c.

The magnitude of change in HbA1c from 9.4% that patients considered a true change reflects the difference a HbA1c method should be able to detect, and thus the patient-derived CD for HbA1c. The calculated CVa values based on these CDs at the 80% and 95% confidence levels are shown in Table 3 . The results show that the responders have higher quality expectations when HbA1c is increasing compared with decreasing from 9.4%. Approximately one-half of the patients indicated that for increasing HbA1c (80% confidence), the resulting CVa should be <=3.1%, assuming a bias of 0%. The values were not significantly different for the two knowledge groups, but the response rates were significantly lower on questions 6 and 7 for the low-knowledge group compared with the high-knowledge group (67% and 58% vs 90% and 79%, respectively; P <0.01).


View this table:
[in this window]
[in a new window]
  		Table 3. Analytical imprecision (CVa)1 calculated from CDs stated by patients (questions 6 and 7).


   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
The patients in our study were experienced in SMBG, with a mean time since diagnosis of 14.7 years. They were recruited consecutively and represent a cross-sectional sample of our clinic’s diabetes population; we have no reason to believe that they are different from other type 1 patients in Norway. The patients studied performed SMBG a mean of 11 times/week, which is lower than recommended by the American Diabetes Association (13), but the relationship between frequency of SMBG and long-term outcome is not well established. Like most diabetes patients, they have, over the years, become more knowledgeable about HbA1c and their diabetes through educational efforts of their caregivers and, increasingly, from other sources of information. Our general question regarding knowledge level was designed to get a simple expression of perceived patient knowledge about HbA1c. A higher percentage of the more experienced patients (longer diabetes duration and SMBG performance) were in the high-knowledge group, which may be explained by their accumulation of knowledge over the years. The patients who had performed SMBG for the longest period of time tended to be more knowledgeable. We did not find associations between perceived knowledge and the HbA1c targets and thresholds stated. Several authors point to this as a more complex relationship and emphasize that knowledge, attitude, and motivation are most important for patients’ ability to take therapeutic actions to maintain or improve their HbA1c values (19)(20)(21)(22)(23). However, we did find a significantly lower response rate on all HbA1c questions for the low-knowledge compared with the high-knowledge group, indicating that the former group found the questions more difficult. On the other hand, even if the nonresponders hypothetically had responded identically to the rest of the low-knowledge group, the mean differences in responses between the low- and high-knowledge groups would not have reached statistical significance.

More than 80% of the studied subjects knew their last HbA1c value, and 90% responded to the crucial question on what a satisfactory HbA1c value should be. The median HbA1c target value was 7.5%, and 75% of the patients declared their target to be <=8%. This is in line with international recommendations giving a HbA1c target value of 7.0–7.5% (7)(13)(24). Thirteen of 181 patients (7%) gave target values of >=9%, which may be reasonable for patients having difficulty in controlling their blood glucose.

At an HbA1c value of 10% (Table 2Up , question 4), 25% of the patients still did not state that treatment intensification should occur. This might reflect that for some patients, the disease is more difficult to control and that targets, therefore, are individualized rather than based directly on recommended values. The fact that only 25% of patients felt that 6% HbA1c is too low (Table 2Up , question 5), might indicate that many patients have not experienced or are unaware of the serious problems associated with the frequent and sometimes severe hypoglycemia that occurs when HbA1c decreases to this concentration (7). This is underscored by the finding that ~25% of the patients indicated that therapeutic actions (less-intense therapy) can be postponed at a HbA1c value of 5.0%. The well-controlled patients set lower targets and adjusted their therapy on lower HbA1c concentrations.

On questions 6 and 7, we asked for CDs set by the patients when estimating true changes in HbA1c from 9.4%. The 20–30% who did not respond to these questions probably were unable to judge this issue of CD. The responding patients set lower CDs when HbA1c increased than when it decreased (medians, 0.6% vs 1.4%). In a similar study, general practitioners gave corresponding median CDs of 0.6% and 1.0%, respectively, when asked which changes in HbA1c that they considered true in response to a case history (12). General practitioners overall seemed to have higher quality expectations for the HbA1c analysis compared with the type 1 diabetes patients. This similarity in response patterns from 407 general practitioners and 201 type 1 patients, i.e., higher CDs when HbA1c increases than when it decreases, is shown in Fig. 2 . The same response pattern was found in a study involving family practitioners, internists, and endocrinologists (11). We believe that this finding is attributable to the adverse effect of poorer metabolic control compared with an improvement; consequently, both doctors and patients want to detect smaller "increases" than "decreases" when judging HbA1c results, probably to initiate therapeutic actions. This might imply that both patients and doctors will intensify treatment with <95% confidence that the increase in HbA1c is true, but want to be more confident that a decrease in HbA1c in fact has occurred before making treatment changes. To reflect the optimum quality (18) stated by the patients in this study, a CVa of 3.1% would be satisfactory for 75% of patients when HbA1c is increasing (80% confidence), whereas a CVa of 3.2% would be satisfactory for 75% when HbA1c is decreasing (95% confidence; Table 3Up ).



View larger version (28K):
[in this window]
[in a new window]
  		Figure 2. Minimal changes in HbA1c values (CDs) indicated by type 1 diabetes patients and general practitioners (GPs) (12) to signify improvement or deterioration of metabolic control, given as percentage of increase or decrease.

Some symbols refer to two or more identical observations. See text for further explanation.

Similarly, to establish analytical quality specifications for HbA1c, Larsen (25) stated that the test should be able to detect a true change in HbA1c of >1% (e.g., change in HbA1c from 7% to 8%). In this example, bias should be negligible, specificity should exclude other minor hemoglobins, and the test should be able to measure the lowest occurring HbA1c in healthy individuals. This approach thus would establish CVa goals of 2–4%. This method was described as a way of defining analytical goals for clinical practice but could also be applicable to patients who have agreed on their treatment goals and targets with their doctors. Kolatkar et al. (11) examined changes in HbA1c interpreted by family practitioners, internists, and endocrinologists and found an optimum CV for HbA1c of 2–4%, not taking bias into account.

From the literature and external national quality-control surveys, we know that the most common analytical methods for HbA1c have a CVa of ~3% (12)(26)(27)(28). In the setting of diabetes follow-up, testing of HbA1c typically takes place at intervals of at least 2 or more months. Bias (systematic error of measurement) is a more important part of total analytical error when the time interval between tests is long or different laboratories or lot numbers of reagents are used (16)(29). Including a bias component will put higher demands on patient-derived analytical quality specifications for imprecision (CV) in this setting. When patients and their caregivers set clinical treatment goals, including HbA1c targets, knowledge about analytical quality can be crucial (29)(30), and analytical imprecision will probably be considered most important in the monitoring situation (16).

In conclusion, most of the studied type 1 diabetes patients were aware of their last HbA1c result, and they had relatively high perceived knowledge about HbA1c testing. Well-controlled patients seem to have higher ambitions and therefore set lower targets and act on lower thresholds. Patients apparently act on smaller increases in HbA1c than decreases. These findings correspond with the patterns found for doctors’ use and interpretation of HbA1c values. The patient-derived quality specification for imprecision (CV) is ~3%.


   Footnotes
 
1 Nonstandard abbreviations: HbA1c, glycohemoglobin A1c; SMBG, self-monitoring of blood glucose; and CD, critical difference.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Brookchin RM, Gallop PM. Structure of hemoglobin A1c: nature of the N-terminal ß chain blocking group. Biochem Biophys Res Commun 1968;32:86-93.[ISI][Medline] [Order article via Infotrieve]
  2. Jovanivic L, Peterson CM. The clinical utility of glycosylated hemoglobin. Am J Med 1981;70:331-338.[ISI][Medline] [Order article via Infotrieve]
  3. Bunn H. Nonenzymatic glycosylation of protein: relevance to diabetes. Am J Med 1981;70:325-330.[ISI][Medline] [Order article via Infotrieve]
  4. Goldstein DE, Little RR, Wiedmeyer HM, England JD, Mckenzie EM. Glycated hemoglobin: methodologies and clinical applications. Clin Chem 1986;32:B64-B70.
  5. Brinchmann-Hansen O, Dahl-Jørgensen K, Hanssen KF, Sandvik L. The response of diabetic retinopathy to 41 months of multiple insulin injections. Arch Ophthalmol 1988;106:1242-1246.[Abstract]
  6. Reichard P, Nilsson B-Y, Rosenquist U. The effect of long-term intensified insulin treatment on the development of microvascular complications of diabetes mellitus. N Engl J Med 1993;329:304-309.[Abstract/Free Full Text]
  7. . DCCT Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993;329:977-986.[Abstract/Free Full Text]
  8. Larsen ML, Hørder M, Mogensen EF. Effect of long-term monitoring of glycosylated hemoglobin levels in insulin-dependent diabetes mellitus. N Engl J Med 1990;323:1021-1025.[Abstract]
  9. Skeie S, Thue G, Sandberg S. Patient-derived quality specifications for instruments used in self-monitoring of blood glucose. Clin Chem 2001;47:67-73.[Abstract/Free Full Text]
  10. Geffken G, Winter WE. Hardware and software in diabetes mellitus: performance characteristics of hand-held glucose testing devices and the application of glycemic testing to patients’ daily diabetes management [Editorial]. Clin Chem 2001;47:11-12.[Free Full Text]
  11. Kolatkar NS, Weiss SL, Cembrowski GS, Mazze RS, Hollander P. Comparing methods of estimating maximum allowable analytical error in glycohemoglobin testing [Letter]. Am J Clin Pathol 1995;103:771-772.[ISI][Medline] [Order article via Infotrieve]
  12. Skeie S, Thue G, Sandberg S. Use and interpretation of HbA1c-testing in general practice. Implications for quality of care. Scand J Clin Lab Invest 2000;60:349-356.[ISI][Medline] [Order article via Infotrieve]
  13. . American Diabetes Association. Standards of medical care for patients with diabetes mellitus. Diabetes Care 2000;23:S32-S42.
  14. . American Diabetes Association. Tests of glycemia in diabetes. Diabetes Care 1998;21:S69-S71.
  15. Fraser CG, Harris EK. Generation and application of data on biological variation in clinical chemistry. Crit Rev Clin Lab Sci 1989;27:409-437.[ISI][Medline] [Order article via Infotrieve]
  16. Dybkaer R. Terminological problems around "accuracy" and "uncertainty". Scand J Clin Lab Invest 1998;58:35-46.[ISI][Medline] [Order article via Infotrieve]
  17. Phillipou G, Phillips PJ. Intraindividual variation of glycohemoglobin: implications for interpretation and analytical goals. Clin Chem 1993;39:2305-2308.[Abstract]
  18. Sandberg S, Thue G. Quality specifications derived from objective analyses based upon clinical needs. Scand J Clin Lab Invest 1999;59:531-534.[ISI][Medline] [Order article via Infotrieve]
  19. Buysschaert M, Lepair-Gadisseux N, Weil R, Vandeleene B, Leonet J, Lambert AE. Effect of an in-patient education programme upon the knowledge, behaviour and glycemic control of insulin dependent diabetic patients. Diabete Metab 1985;13:31-36.
  20. Bloomgarden ZT, Karmally W, Metzger J, Brothers M, Nechemias C, Bookman J, et al. Randomized, controlled trial of diabetic patient education: Improved knowledge without improved metabolic status. Diabetes Care 1987;10:263-272.[Abstract]
  21. Lockington T, Powles S, Meadows K, Wise P. Attitudes, knowledge and blood glucose control. Diabet Med 1988;6:309-313.
  22. Lennon GM, Taylor KG, Debney L, Bailey CJ. Knowledge, attitudes, technical competence, and blood glucose control of type 1 diabetic patients during and after an education programme. Diabet Med 1990;7:825-832.[ISI][Medline] [Order article via Infotrieve]
  23. Dunn SM, Beeney LJ, Hoskins PL, Turtle JR. Knowledge and attitude change as predictors of metabolic improvement in diabetes education. Soc Sci Med 1990;31:1135-1141.
  24. Claudi T, Midthjell K, Furuseth K, Hanssen K, Hestvold P-I, Øgar P, eds. NSAM’s action program for diabetes in general practice. Oslo: Norsk Selskap for Allmennmedisin, Norges Diabetesforbund, Statens Helsetilsyn, Statens Institutt for Folkehelse, Den Norske Lægeforening, 1995..
  25. Larsen ML. The clinical usefulness of glycated haemoglobin in diabetes care evaluated by use of a medical technology assessment strategy. Dan Med Bull 1997;44:303-315.[ISI][Medline] [Order article via Infotrieve]
  26. Halwachs-Baumann G, Katzensteiner S, Schnedl W, Pürstner P, Pieber T, Wilders-Truschnig M. Comparative evaluation of three assay systems for automated determination of hemoglobin A1c. Clin Chem 1997;43:511-517.[Abstract/Free Full Text]
  27. Gilbert RE, Goodall I, Young V, Jerums G. Interlaboratory variation of GHb assays in Victoria, Australia. Diabetes Care 1996;19:730-734.[Abstract]
  28. Guthrie R, Hellman R, Kilo C, Hiar CE, Childs B, Fisher R, et al. A multisite physician’s office laboratory evaluation of an immunological method for the measurement of HbA1c. Diabetes Care 1992;15:1494-1498.[Abstract]
  29. Larsen ML, Fraser CG, Petersen PH. A comparison of analytical goals for haemoglobin A1c assays derived using different strategies. Ann Clin Biochem 1991;28:272-278.
  30. Penttilä IM, Gävert J, Julkunen A, Rantanen T. Quality specifications for glycated hemoglobin A1c. Upsala J Med Sci 1993;98:395-399.[ISI][Medline] [Order article via Infotrieve]



The following articles in journals at HighWire Press have cited this article:


Home page
 Clin. DiabetesHome page
A. M. Delamater
Clinical Use of Hemoglobin A1c to Improve Diabetes Management
Clin. Diabetes, January 1, 2006; 24(1): 6 - 8.
[Full Text] [PDF]

Home page
 Clin. Chem.Home page
S. Skeie, C. Perich, C. Ricos, A. Araczki, A. R. Horvath, W. P. Oosterhuis, T. Bubner, G. Nordin, R. Delport, G. Thue, et al.
Postanalytical External Quality Assessment of Blood Glucose and Hemoglobin A1c: An International Survey
Clin. Chem., July 1, 2005; 51(7): 1145 - 1153.
[Abstract] [Full Text] [PDF]

Home page
 Clin. Chem.Home page
P. Luraschi, S. Brambilla, R. Mozzi, G. Cattozzo, and C. Franzini
Monitoring Analytical Quality in Routine Glycohemoglobin Measurements
Clin. Chem., September 1, 2002; 48(9): 1594 - 1597.
[Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit an electronic Letter to
the Editor about this paper
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (6)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Skeie, S.
Right arrow Articles by Sandberg, S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Skeie, S.
Right arrow Articles by Sandberg, S.
Related Collections
Right arrow Evidence Based Laboratory Medicine and Test Utilization
Right arrow Endocrinology and Metabolism

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS