A Comparison of Costs among Patients with Type 2 Diabetes Mellitus Who Initiated Therapy with Exenatide or Insulin Glargine

Article excerpt

Background

Type 2 diabetes mellitus is a prevalent and costly disease in the US.[1] In 2007, 17.5 million people in this country had a diagnosis of type 2 diabetes, and acute care costs of the disease totalled $US174 billion, including $US116 billion in excess medical expenditures and $US58 billion in reduced national productivity.[1] The medical costs attributed to type 2 diabetes in 2007 included $US27 billion for direct care, $US58 billion for diabetes-related chronic complications and $US31 billion in excess general medical costs.[1]

The cornerstone of treatment for type 2 diabetes is the management of glycaemia, with the goal of therapy being a haemoglobin A1c (HbA1c ) concentration of <7%.[2] Exenatide (Byetta® ) and insulin glargine (Lantus® ) are two injectable medications commonly prescribed for glycaemic control among patients with type 2 diabetes whose blood glucose concentrations are not well controlled by oral antidiabetic therapies.[3] Insulin glargine was approved by the US FDA for the US market in April 2000 in a once-daily formulation for subcutaneous injection.[4,5] Insulin glargine is a basal insulin analogue, produced by a chemical modification of regular human insulin; primarily, it reduces fasting plasma glucose and provides relatively constant basal insulin concentrations over 24 hours.[4] Exenatide was approved by the FDA for the US market in April 2005 in a twice-daily formulation for subcutaneous injection.[6,7] A glugacon-1-like peptide (GLP-1), exenatide works through multiple mechanisms, including improving glucose metabolism through the stimulation of insulin secretion when the blood glucose concentration is elevated,[8,9] suppressing inappropriately high glucagon secretion and thus protecting against hyperglycaemia,[10,11] and slowing gastric emptying.[12,13]

Two head-to-head clinical trials have compared the outcomes of patients using twice-daily exenatide and insulin glargine.[14,15] According to the evidence of these trials, exenatide and insulin glargine are equally effective at improving glycaemic control. In the first trial, HbA1c was reduced by 1.1% from baseline after 26 weeks with both drugs.[14] In the second study, both drugs were associated with similar, statistically significant within-group improvements in HbA1c (-1.36 ± 0.09%; p < 0.001 within treatment group) from a mean baseline level of 9.0%.[15]

Beyond control of blood glucose concentrations, these trials have also shown exenatide to have some distinct advantages over insulin glargine. For instance, the use of insulin glargine therapy was associated with weight gain, whereas the use of exenatide was associated with weight loss. For example, clinical trial results found that, over 26 weeks, the use of exenatide was associated with a 2.3 kg weight loss, while the use of insulin glargine was associated with a 1.8 kg weight gain.[14] Similarly, a 32-week trial of individuals whose blood glucose was previously uncontrolled on metformin or a sulfonylurea showed that the between-group difference in weight change was statistically significant in favour of exenatide (-2.3 kg; p < 0.0001).[15] Considering the well documented links between obesity, diabetes and additional health risk factors, bodyweight is a concern for patients with diabetes as well as their care providers.[16-20] However, it should be noted that research has not demonstrated that the differences found in these studies were associated with improvements in patient health. In addition to the favourable weight profile associated with exenatide, in both trials, hypoglycaemia was more of an issue for users of insulin glargine.[14,15] However, use of exenatide has been found to be associated with significantly more gastrointestinal symptoms, including nausea, vomiting and diarrhoea, than insulin glargine.[15,21]

Now that the two drugs have been on the market for a number of years, it is possible and necessary to compare their associated costs. …