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The frequency of testing for glycated haemoglobin, HbA1c, is linked to the probability of achieving target levels in patients with suboptimally controlled diabetes mellitus

  • Christopher J. Duff , Ivonne Solis-Trapala , Owen J. Driskell , David Holland , Helen Wright , Jenna L. Waldron , Clare Ford , Jonathan J. Scargill , Martin Tran , Fahmy W.F. Hanna , R. John Pemberton , Adrian Heald and Anthony A. Fryer ORCID logo EMAIL logo

Abstract

Background

We previously showed, in patients with diabetes, that >50% of monitoring tests for glycated haemoglobin (HbA1c) are outside recommended intervals and that this is linked to diabetes control. Here, we examined the effect of tests/year on achievement of commonly utilised HbA1c targets and on HbA1c changes over time.

Methods

Data on 20,690 adults with diabetes with a baseline HbA1c of >53 mmol/mol (7%) were extracted from Clinical Biochemistry Laboratory records at three UK hospitals. We examined the effect of HbA1c tests/year on (i) the probability of achieving targets of ≤53 mmol/mol (7%) and ≤48 mmol/mol (6.5%) in a year using multi-state modelling and (ii) the changes in mean HbA1c using a linear mixed-effects model.

Results

The probabilities of achieving ≤53 mmol/mol (7%) and ≤48 mmol/mol (6.5%) targets within 1 year were 0.20 (95% confidence interval: 0.19–0.21) and 0.10 (0.09–0.10), respectively. Compared with four tests/year, having one test or more than four tests/year were associated with lower likelihoods of achieving either target; two to three tests/year gave similar likelihoods to four tests/year. Mean HbA1c levels were higher in patients who had one test/year compared to those with four tests/year (mean difference: 2.64 mmol/mol [0.24%], p<0.001).

Conclusions

We showed that ≥80% of patients with suboptimal control are not achieving commonly recommended HbA1c targets within 1 year, highlighting the major challenge facing healthcare services. We also demonstrated that, although appropriate monitoring frequency is important, testing every 6 months is as effective as quarterly testing, supporting international recommendations. We suggest that the importance HbA1c monitoring frequency is being insufficiently recognised in diabetes management.


Corresponding author: Prof. Anthony A. Fryer, Department of Clinical Biochemistry, Keele University, Institute for Applied Clinical Sciences, University Hospitals of North Midlands, Newcastle Road, Stoke-on-Trent, Staffordshire ST4 6QG, UK, Phone: +44 1782 674245, Fax: +44 844 244 8602

Acknowledgments

We are grateful to the members of Diabetes U.K. (North Staffordshire Branch) for advice and feedback on the patient aspects of the study.

  1. Author contributions: O.J.D., I.S-T, C.J.D. and A.A.F. wrote the initial draft of the manuscript, performed the data analysis and provided clinical advice and critique from a clinical laboratory scientist perspective. I.S-T. developed the statistical modelling, conducted the statistical analysis, contributed to the interpretation of results and drafted the manuscript. J.L.W., J.J.S, and M.T. performed the data extraction from the three centres. H.W. supported data preparation for analysis. C.F. provided clinical advice and critique from a clinical laboratory scientist perspective. A.H. and F.W.H. provided clinical advice and critique from a clinical/research diabetologist perspective. R.J.P. provided a patient perspective and ensured the team had a patient-centred focus. All authors reviewed and edited the manuscript. A.A.F. is the guarantor of this work and, as such, had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: The study was supported by a National Institute for Health Research Healthcare Scientist Fellowship award to O.J.D. (HCS/08/011, Funder Id: 10.13039/501100000659), supervised by A.A.F.

  3. Employment or leadership: None declared.

  4. Honorarium: None declared.

  5. Competing interests: The funding organisation played no role in the study design; in the collection, analysis and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.

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Supplementary Material

The online version of this article offers supplementary material ((https://doi.org/10.1515/cclm-2018-0503).


Received: 2018-05-11
Accepted: 2018-09-04
Published Online: 2018-10-02
Published in Print: 2018-12-19

©2019 Walter de Gruyter GmbH, Berlin/Boston

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