Use of, time to, and type of first add-on anti-hyperglycaemic therapy to metformin in Australia, 2018-2022.

AIMS

The aim of this study was to examine contemporary trends in the use of, time to, and type of first add-on anti-hyperglycaemic therapy to metformin in Australia.

METHODS

We used the dispensing records of a 10% random sample of Pharmaceutical Benefits Scheme (PBS) eligible people. We included people aged 40 years and older initiating metformin from 1 January 2018 to 31 December 2020. Our primary outcome was first add-on anti-hyperglycaemic medicine within 2 years of metformin initiation. We analysed time to dispensing of first add-on therapy. All analyses were stratified by metformin initiation year.

RESULTS

Overall, 38 747 people aged 40 years and older initiated metformin between 2018 and 2020. Approximately one-third (n = 12 946) of people received add-on therapy with the proportion increasing slightly by year of metformin initiation (32.3% in 2018 to 34.8% in 2020). Amongst people with add-on therapy following metformin initiation, sodium-glucose cotransporter 2 inhibitor (SGLT2i) use increased from 28.8% (2018) to 35.0% (2020), and glucagon-like peptide-1 receptor agonists (GLP-1 RA) increased from 3.0% to 9.6%, respectively. Dipeptidyl peptidase-4 inhibitors and sulfonylureas as first add-on therapy decreased and insulin remained stable. One-third of people with add-on therapy initiated the therapy on the same day metformin was initiated, i.e. initial combination therapy.

CONCLUSIONS

Amongst people initiating metformin from 2018 to 2020, there was an increasing proportion of SGLT2i and GLP-1 RA being used as first add-on therapy. However, the overall prevalence of add-on therapy was low. Advocacy to promote add-on therapy with cardiorenal beneficial medicines is critical to reduce type 2 diabetes morbidity and mortality.