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Adherence to metformin in people with type 2 diabetes mellitus: results from the first New Zealand-wide study

Tuesday 19 November 2019 2:08pm

In a national study, researchers from the Pharmacoepidemiology Research Network at the University of Otago have found sub-optimal levels of adherence to metformin, the recommended first-line drug used to treat type 2 diabetes.

Simon Horsburgh Image
Dr Simon Horsburgh

Around 210,000 New Zealand adults are estimated to have been diagnosed with type 2 diabetes, and Pacific peoples and Māori are particularly affected. Type 2 diabetes is a serious disease and can lead to complications such as cardiovascular disease, blindness, kidney failure, and lower-limb amputation. Good control of blood glucose levels has been shown to reduce the risk of these complications.

Overseas research has identified that many people with type 2 diabetes are not sufficiently adherent to their antidiabetic medications to achieve good blood glucose control. However, until now there have been no national-level studies of metformin adherence in New Zealand.

The Otago researchers used anonymised national pharmaceutical dispensing and health data from the Ministry of Health to assess medication adherence in 85,066 people with type 2 diabetes who started taking metformin between 2006 and 2014.

In their paper recently published in Diabetes Research and Clinical Practice, the researchers report that younger people and Māori and Pacific peoples had less optimal adherence. People receiving a greater number of non-diabetic medications and those with a history of cardiovascular disease or a recent cancer diagnosis had better adherence.

Lead author, Dr Simon Horsburgh, says the findings for Māori and Pacific peoples were particularly concerning given the higher prevalence of type 2 diabetes in these groups. Combined with existing evidence about poor clinical experiences and difficulties with accessing health services, they point to the need for improvements across all levels of the health system to better respond to the needs of Māori and Pacific peoples with type 2 diabetes.

The study was funded by a grant from the Health Research Council of New Zealand and the Pharmaceutical Management Agency (PHARMAC) of New Zealand.

Publication details

Horsburgh S, Barson D, Zeng J, Sharples K, Parkin L. Adherence to metformin monotherapy in people with type 2 diabetes mellitus in New Zealand. Diabetes Research and Clinical Practice. doi:10.1016/j.diabres.2019.107902