Temporal trends in the use of antidiabetic medicines: a nationwide 9-year study in older people living in New Zealand

Background: The global burden of diabetes is increasing worldwide. The aim of the study was to investigate the trends in use of antidiabetic medicines among older New Zealanders between 2005 and 2013, and to perform a separate analysis by age, sex, ethnicity, district health board domicile and socioeconomic deprivation index.

Methods: The study population included individuals’ aged 65 years and older living in New Zealand (NZ) captured in the pharmaceutical collections. Repeated cross-sectional analysis of population-level dispensing data was conducted from 1 January 2005 to 31 December 2013. Linear regression model using a gamma link function was used to estimate prevalence ratios and trends between 2005 and 2013. The main outcome measure was the prevalence of antidiabetic medicines in older New Zealanders.

Results: The prevalence of antidiabetic medicines in older New Zealanders increased by 17.6% between 2005 and 2013. Individuals in the 70–74 age group had the highest utilization of each of the classes of antidiabetic medicines and those aged ⩾85 had the lowest utilization. Among the antidiabetic class of medicines, utilization of sulfonylureas was highest and alpha-glucosidase inhibitors the least. The utilization of thiazolidinediones increased over the study period. In 2013, insulin isophane and insulin glargine were the most common insulin analogues used. Insulin use was high in those aged ⩾85 years across the entire study period. The utilization of metformin increased gradually throughout the study period (by 43.9% in 2013 compared with 2005).

Conclusion: This population-level study showed an increase in utilization of antidiabetic medicines in older people in NZ from 2005 to 2013; however, the increase does not seem to parallel the proportional increase in prevalence of diabetes for the study period. Improving access to newer antidiabetic medicines in line with emerging evidence should be a consideration for decision makers.