Adherence to oral glucose-lowering therapies and associations with 1-year HbA1c: A retrospective cohort analysis in a large primary care database

Andrew J. Farmer (Lead / Corresponding author), Lauren R. Rodgers, Mike Lonergan, Beverley Shields, Michael N. Weedon, Louise Donnelly, Rury R. Holman, Ewan R. Pearson, Andrew T. Hattersley

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    61 Citations (Scopus)
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    Objective The impact of taking oral glucose-lowering medicines intermittently, rather than as recommended, is unclear. We conducted a retrospective cohort study using community-acquired U.K. clinical data (Clinical Practice Research Database [CPRD] and GoDARTS database) to examine the prevalence of nonadherence to treatment for type 2 diabetes and investigate its potential impact on HbA1c reduction stratified by type of glucose-lowering medication. 

    Research Design and Methods Data were extracted for patients treated between 2004 and 2014 who were newly prescribed metformin, sulfonylurea, thiazolidinedione, or dipeptidyl peptidase 4 inhibitors and who continued to obtain prescriptions over 1 year. Cohorts were defined by prescribed medication type, and good adherence was defined as a medication possession ratio ≥0.8. Linear regression was used to determine potential associations between adherence and 1-year baseline-adjusted HbA1c reduction. 

    Results In CPRD and GoDARTS, 13% and 15% of patients, respectively, were nonadherent. Proportions of nonadherent patients varied by the oral glucose-lowering treatment prescribed (range 8.6% [thiazolidinedione] to 18.8% [metformin]). Nonadherent, compared with adherent, patients had a smaller HbA1c reduction (0.4% [4.4 mmol/mol] and 0.46% [5.0 mmol/mol] for CPRD and GoDARTs, respectively). Difference in HbA1c response for adherent compared with nonadherent patients varied by drug (range 0.38% [4.1 mmol/mol] to 0.75% [8.2 mmol/mol] lower in adherent group). Decreasing levels of adherence were consistently associated with a smaller reduction in HbA1c.

    Conclusions Reduced medication adherence for commonly used glucose-lowering therapies among patients persisting with treatment is associated with smaller HbA1c reductions compared with those taking treatment as recommended. Differences observed in HbA1c responses to glucose-lowering treatments may be explained in part by their intermittent use.

    Original languageEnglish
    Pages (from-to)258-263
    Number of pages6
    JournalDiabetes Care
    Issue number2
    Publication statusPublished - 1 Feb 2016

    ASJC Scopus subject areas

    • Internal Medicine
    • Endocrinology, Diabetes and Metabolism
    • Advanced and Specialised Nursing


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