Use patterns of antidiabetic regimens by patients with type 2 diabetes

To describe the use patterns of metformin-based antidiabetic regimens in patients with type 2 diabetes and to identify predictors of initiating metformin monotherapy.

By using administrative databases from Alberta, Canada, we identified all metformin users ages 65 years and older between 1998 and 2010. Rates of metformin use, either alone or in combination with other antidiabetic drugs, were evaluated at 6-month intervals. All rates were direct age- and sex-standardized using the 2006 Alberta census. Trends over time were assessed using Joinpoint regression software (National Cancer Institute, USA). In addition, a cohort of new users of antidiabetic drugs was identified and multivariable logistic regression models were constructed to identify independent predictors of receiving initial treatment with metformin monotherapy.

Metformin monotherapy became the most common metformin-based regimen (508 of 1000 persons in 2010). Sulfonylureas were the most prevalent add-on drug to metformin; however, their use significantly decreased from 548 of 1000 in 1998 to 182 of 1000 persons in 2010 (67% reduction; p<0.001), with more patients using newer drugs, mainly thiazolidinediones (103 of 1000 persons in 2007). Combination therapy of metformin with glinides or insulin also significantly increased during the same period. Compared with patients starting sulfonylurea monotherapy, patients starting metformin monotherapy were younger, had fewer cardiovascular complications and lower healthcare use rates.

In accordance with the clinical practice guidelines, patients with type 2 diabetes manage hyperglycemia mainly with metformin monotherapy and sulfonylureas are the most common add-on therapy. Older age and the presence of nephropathy, liver disease or congestive heart failure were important predictors for starting sulfonylurea monotherapy rather than metformin monotherapy.