Long-term adherence to glucose-lowering medications in adults with diabetes: A data linkage study

To determine the adherence rate in users of each class of glucose-lowering medication and identify the key socio-demographic factors influencing adherence.

The 45 and Up Study is an ongoing cohort study of residents aged ≥45 years in New South Wales, Australia. We analysed Pharmaceutical Benefits Scheme records from 2013 to 2019 of the 21 341 study participants who self-reported having diabetes. Medication adherence was estimated as the proportion of days covered for each 12-month period for up to the fifth 12-month period.

A consistent pattern was observed across all drug classes, where the percentage of adherent (proportion of days covered ≥0.8) users was highest in the first 12 months, followed by a drop in the second 12 months. For prevalent users on the same drug class for the full 5-year period, higher percentages of adherent users compared to the first 12 months were observed for glucagon-like peptide 1 receptor agonists (77.7% vs 74.2%). For incident users on the same drug class for the full 5-year period, a higher percentage of adherent users compared to the first 12 months was observed for sodium-glucose cotransporter 2 inhibitors (84.2% vs 78.4%). Moreover, no socio-demographic subgroup was consistently more or less adherent to medications.

Initial adherence was good and remained relatively high over time in this cohort. Nevertheless, adherence was still a challenge in some individuals. Practitioners should recognize the possibility of non-adherence and consider this at each consultation.