Pharmacological treatment initiation for type 2 diabetes in Australia: are the guidelines being followed?

Aim
To determine the patterns and predictors of pharmacological treatment initiation for type 2 diabetes and whether treatment initiation is consistent with Australian clinical practice guidelines that recommend metformin monotherapy.

Methods
Individuals aged 40–99 years initiating a non‐insulin type 2 diabetes medication between July 2013 and February 2018 were identified from a 10% random national sample of pharmacy dispensing data. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the predictors of initiating sulfonylurea monotherapy, non‐guideline monotherapy and combination therapy compared with metformin monotherapy. Predictors included age, sex, initiation year and comorbidities determined using the Rx‐Risk comorbidity index.

Results
Of the 47 860 initiators, [47% women, mean age 60.7 (sd 12.1) years], 85.8%, 4.6%, 1.9% and 7.7% received metformin monotherapy, sulfonylurea monotherapy, non‐guideline monotherapy and combination therapy, respectively. Increasing age was associated with increasing odds of initiating sulfonylurea monotherapy and non‐guideline monotherapy. Combination therapy initiation was less likely in women (OR 0.74, 95% CI 0.69–0.79) and people with more comorbidities (e.g. OR 0.36, 95% CI 0.29–0.44 for seven or more comorbidities vs. no comorbidities) but more likely in congestive heart failure (OR 1.42, 95% CI 1.22–1.65), cerebrovascular disease (OR 1.50, 95% CI 1.32–1.69) and dyslipidaemia (OR 1.29, 95% CI 1.19–1.40).

Conclusion
Treatment initiation in Australia is largely consistent with clinical practice guidelines, with 86% of individuals initiating metformin monotherapy. Initiation on combination therapy was more common in men and in those with fewer comorbidities.