Medication Use in Type 1 Diabetes and the Association with Socioeconomic Disadvantage: Analysis of a National Linked Dataset.

Objectives: To explore trends in the receipt of commonly prescribed medications (beyond insulin) in people with type 1 diabetes in Australia, including polypharmacy, and to investigate socioeconomic disparities across these trends. Methods: A retrospective analysis of 68,287 people with type 1 diabetes registered on the National Diabetes Services Scheme between 2013 and 2019, and linked to the Australian pharmaceutical claims database to capture medication use. The proportion of people with type 1 diabetes dispensed a medication class was assessed in each year, and by levels of Index of Relative Social Disadvantage. Results: The study population comprised 37,055 (54.3%) males and 31,232 (45.7%) females captured between 2013 and 2019, with an overall median age of 38.8 (interquartile range [IQR]: 26.1-53.3) years and median diabetes duration of 17.0 (IQR: 7.9-25.7) years. The median number of medications used in the study population was five (IQR: 3-8). Trends in receipt of commonly prescribed medications remained relatively stable between 2013 and 2019, except for the use of noninsulin (adjuvant) glucose-lowering agents, which increased. In 2019, compared with people in the least disadvantaged areas, those in the most disadvantaged areas were more likely to be receiving adjuvant glucose-lowering therapy (crude rates 21.5% vs. 11.6%), antihypertensive therapies (36.1% vs. 28.8%), lipid-lowering therapies (35.7% vs. 29.7%), antithrombotic medication (8.9% vs. 5.6%), proton pump inhibitors (25.2% vs. 17.1%), medications for asthma (13.2% vs. 8.4%), and medications for mental health (27.5% vs. 21.5%). Polypharmacy (defined as ≥5 medications) was more likely in those in the most disadvantaged areas compared with those in the least disadvantaged areas (58.8% vs. 48.5%). Even after adjustment for patient factors, differences in medication use and polypharmacy across socioeconomic strata persisted. Conclusions: Receipt of commonly prescribed medications in type 1 diabetes and polypharmacy were associated with increased socioeconomic disadvantage.