Modelling cost effectiveness of insulin glargine for the treatment of type 1 and 2 diabetes in Canada

Background and objective: Intensive insulin therapy improves glycosylated haemoglobin (Hb(A1C)) levels and delays the onset of long-term diabetes-related complications. Current treatment guidelines recommend maintaining a glycosylated haemoglobin (Hb(A1C)) of <= 7% in patients with type 1 and 2 diabetes mellitus. However, the risk of hypoglycaemia increases with lower Hb(A1C) levels. As such, patients often choose to settle for suboptimal glucose control in order to prevent hypoglycaemic events. At a given Hb(A1C) level, treatment with insulin glargine results in a lower risk of hypoglycaemia in type 1 and 2 diabetes compared with NPH insulin. It has been proposed that the lower hypoglycaemic risk will allow more patients to achieve target Hb(A1C) levels with insulin glargine compared with NPH insulin. The objective of this study was to assess the cost effectiveness of insulin glargine compared with NPH insulin in patients with type 1 or 2 diabetes who had inadequate glycaemic control. Methods: A long-term, state-transition model was developed to simulate the natural history of type 1 and 2 diabetes. Risks of diabetes-related macro- and microvascular complications and mortality by Hb(A1C) levels were estimated based on the UKPDS (United Kingdom Prospective Diabetes Study). Outcome measures included complication rates and associated costs, insulin costs, life years (LYs) and QALYs. The baseline analysis was conducted for patients with type 1 and 2 diabetes (aged 27 and 53 years, respectively) with Hb(A1C) levels >7%, using a 36-year time horizon and a Canadian public payer perspective. Costs and effects were discounted at 5% per annum. Univariate sensitivity analyses were performed on key model inputs. All costs were reported in $Can (2005 values). Results: The NPH insulin group had lower total costs than the insulin glargine group for patients with inadequately controlled diabetes (Hb(A1C) >7%; lifetime difference $Can 1398 and $Can 1992, respectively, in type 1 and 2 diabetes). However, patients treated with insulin glargine had greater total and quality-adjusted life expectancy than those who received NPH insulin (incremental LY = 0.08 and QALYs = 0.07 in type 1 diabetes and incremental LY = 0.25 and QALYs = 0.23 in type 2 diabetes). The weighted incremental cost per LY gained and QALY gained were $Can18 661 and $Can20 799, respectively, in type 1 diabetes and $Can8041 and $Can8618, respectively, in type 2 diabetes (discounted results). Conclusions: The cost-effectiveness ratios for insulin glargine use for type 1and 2 diabetes provide evidence for its adoption from a Canadian healthcare payer perspective.