The impact of sodium glucose co-transporter 2 inhibitors and glucagon-like peptide 1 receptor agonists on insulin utilisation and costs in Australia: a national retrospective observational cross-sectional study

Background: Global insulin requirements for type 2 diabetes were predicted to increase by more than 20% from 2018 to 2030. However, this did not anticipate the rapid increase in use of glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors that has occurred over recent years. The current study aims to examine changes in insulin utilisation and costs in Australia from 2003 to 2023.

Methods: We conducted a large-scale observational study of national insulin utilisation and expenditure in Australia from 2003 to 2023 using the Australian Pharmaceutical Benefits Scheme. The proportion of insulin-treated people with type 2 diabetes between 2013 and 2023 was estimated using National Diabetes Services Scheme data. Joinpoint models and interrupted time series analysis were used to examine utilisation trends.

Findings: Insulin utilisation (units of insulin per person with diabetes) increased by an average of 2.71% per annum (95% CI 1.97, 3.73) from 2003 to 2015, then fell by 2.70% per annum (95% CI -4.55, -1.39) from 2015 to 2023. The proportion of insulin-treated people with type 2 diabetes increased by 1.00% per annum (95% CI 0.81, 1.25) from 2013 to 2020, then fell by 0.66% per annum (95% CI -1.62, -0.04) from 2020 to 2023. A 43% reduction in inflation-adjusted insulin expenditure was observed between 2015 and 2023 due to a combination of reduced utilisation and reduction in the price of insulin glargine.

Interpretation: Projected global insulin requirements and costs may be less than previously anticipated if reduced use of insulin in Australia is similarly observed in other countries.

Funding: No funding was received for this study.