Healthcare Costs Associated with Change in Body Mass Index in Patients with Type 2 Diabetes Mellitus in Spain: The ECOBIM Study

Background: Weight management is considered a key therapeutic strategy in type 2 diabetes mellitus. However, little is known about the impact of weight loss or body mass index (BMI) reduction on type 2 diabetes-related healthcare costs. Objective: The aim of this study was to estimate the economic impact of change in BMI among patients with type 2 diabetes mellitus from the Spanish healthcare system perspective. Methods: The ECOBIM study is an observational, non-interventional study in which data on BMI change and costs incurred by patients with type 2 diabetes were collected cross-sectionally and retrospectively for a 12-month period. Generalized linear mixed models were applied to estimate the effects of (i) BMI change in general (one-slope model); (ii) BMI gain and no BMI gain (two-slope model); and (iii) BMI gain and no BMI gain among obese and non-obese patients (four-slope model). Results: We studied 738 patients with a mean (SD) age of 66 (11) years and BMI of 30.6 (5.2) kg/m(2). During the 12-month study period, 41.2% of patients gained BMI (BMI gainers) and 58.8% experienced either loss (52.2%) or no change (6.6%) in BMI (non-BMI gainers). One-unit gain (or loss) in BMI was significantly (p<0.001) associated with a 2.4% cost increase (or decrease) [one-slope model]. Every unit gain in BMI was associated with a 20.0% increase in costs among BMI gainers while losing one unit was associated with an 8.0% decrease in costs among non-BMI gainers (two-slope model, p<0.01). The economic benefit associated with reducing one BMI unit was 9.4% cost decrease in obese and 2.7% in non-obese patients (4-slope model). Conclusion: An increase in BMI among patients with type 2 diabetes was associated with increased 1-year direct healthcare costs. A reduction in BMI was associated with appreciable short-term economic benefits, especially in obese patients.