Cost Effectiveness of Insulin Glargine Plus Oral Antidiabetes Drugs Compared with Premixed Insulin Alone in Patients with Type 2 Diabetes Mellitus in Canada

Article excerpt

Background

Type 2 diabetes mellitus is a chronic condition that can substantially affect patient quality of life (QOL), and is associated with considerable increases in healthcare costs. Estimates from the Canadian Diabetes Association (CDA) suggest that diabetes will cost the Canadian healthcare system $Can15.6 billion annually from 2010; this is expected to increase to $Can19.2 billion by 2020.[1] According to a 2005 report from the Public Health Agency of Canada,[2] 5.5% of Canadians, or 1.8 million individuals, have diagnosed diabetes. This represents 7.1% of individuals aged ≥20 years and 18% of those aged ≥60 years.

Launched in 2004 by what is now the Canadian Agency for Drugs and Technologies in Health (CADTH), the Canadian Optimal Medication Prescribing and Utilization Service (COMPUS) is a nationally coordinated programme funded by Health Canada. One priority of COMPUS is to provide Canadian stakeholders with empirically based information regarding current and emerging trends in the treatment of diabetes. The prioritization is based on several factors, including the size of the diabetes patient population, and a high level of potential impact on health and economic outcomes relevant to multiple jurisdictions in Canada.[3]

Recent reports produced by COMPUS that evaluated the cost effectiveness of treatment interventions and management tools for (type 1 and type 2) diabetes include an evaluation of insulin analogues and an evaluation of self-monitoring of blood glucose.[3,4] In both studies, projections of long-term clinical and economic outcomes were based primarily on improvements in glycaemic control as defined by changes in glycosylated haemoglobin A1c (HbA1c ).

In type 2 diabetes, glycaemic control (HbA1c levels <7%) has been shown to reduce associated microvascular complications such as diabetic nephropathy and retinopathy, as well as macrovascular complications such as stroke and coronary artery disease.[5] Generally, patients with type 2 diabetes who are not able to maintain adequate glucose control with oral antidiabetes drugs (OADs) will eventually need to initiate insulin therapy.[6] Unfortunately, insulin can lead to less than adequate levels of blood glucose. Hypoglycaemia is a complication that can range in severity from mild or moderate (with symptoms such as a headache) to severe (which could result in a coma or other conditions requiring costly hospitalizations).[7]

Two options currently recommended by the CDA for initiating insulin therapy in patients with type 2 diabetes who are no longer responsive to OADs are premixed insulin therapy, and insulin glargine plus OADs.[6] The combination of intermediate-acting neutral protamine Hagedorn (NPH) and regular human insulin is intended to provide a supplement to basal insulin and short-term meal coverage. Insulin glargine is intended to provide a longer duration of action and more constant blood glucose levels than mixed insulin regimens.

A head-to-head comparison of the effectiveness of insulin glargine plus OADs versus premixed insulin alone, in patients with type 2 diabetes that was inadequately controlled with OADs, was performed by Janka et al.[8] This 24-week, multicentre, open-label, parallel-group, randomized study included 371 patients from ten European countries. Patients were aged 35-75 years, had diabetes for ≥1 year, were insulin-naive, and had been treated with OADs (sulfonylurea plus metformin) for ≥1 month.

Patients were randomized to either once-daily insulin glargine (LANTUS® , sanofi-aventis, Bridgewater, NJ, USA) plus glimepiride and metformin, or twice-daily premixed insulin (a combination of 70% NPH-human insulin isophane suspension, and 30% regular human insulin) [Humulin® , Eli Lilly and Company, Indianapolis, IN, USA; Novolin® , Novo Nordisk, Bagsvaerd, Denmark] only. The primary efficacy measure was change in HbA1c from baseline to endpoint. Secondary efficacy measures included mean fasting blood glucose (FBG), proportion of patients with FBG ≤100 mg/dL (≤5. …