Time to insulin treatment and factors associated with insulin prescription in Swedish patients with type 2 diabetes.

Aims: The purpose of this study was to investigate the time between the start of OAD treatment and the initiation of insulin therapy and to identify the factors associated with insulin prescription among Swedish patients with type 2 diabetes in Uppsala County.

Methods: Retrospective, population-based, primary-care data gathered within the Swedish RECAP-DM study were used to identify type 2 diabetic patients who initiated OAD treatment. A Kaplan-Meier survival estimate for time to initiation of insulin therapy was generated and factors associated with insulin prescription were tested using a Cox proportional-hazards model.

Results: Within 6 years of starting OAD treatment, an estimated 25% of Swedish patients with type 2 diabetes will be prescribed insulin (95% CI: 0.23-0.26) and, within 10 years, this figure will rise to 42% (95% CI: 0.39-0.45). The probability of insulin prescription was increased in patients aged less than 65 years (HR=1.24, 95% CI: 1.03-1.50) and in those who initiated OAD treatment with more than one agent (HR=2.71, 95% CI: 2.15-3.43). HbA(1c) at the time of starting OAD treatment was also related to the probability of insulin prescription (HR=1.20, 95% CI: 1.146-1.25).

Conclusion: Many type 2 diabetic patients who begin treatment with an OAD will eventually be prescribed insulin. Age, disease severity and the type of prior treatment may affect the rate of the transition.