Excess Health Care Costs of Obesity in Adults with Diabetes Mellitus: a Claims Data Analysis

Abstract

Body weight management is a key factor in diabetes mellitus. However, both behavioral and pharmacological innovations to manage obesity may imply additional costs. In order to provide further insights into the role of obesity in diabetes-associated resource consumption, this study aims to estimate incremental costs of concomitant obesity in German adult patients (≥ 18 years) with different types of diabetes. Adopting a third-party payer perspective, claims data from a German statutory sickness fund (N=1,094,496) were analyzed for costs of annual drug prescriptions and out- and inpatient care in adult beneficiaries with diabetes in 2004. Using diagnostic information, 37,570 beneficiaries with diabetes were identified. Concomitant obesity was assessed by ICD-10-codes (E66) in the claims data. Adjusting for sex, age, and micro- and macro-vascular complications, one generalized gamma regression model with the log link was performed for type 2 diabetes patients (N=24,562), type 1 diabetes patients (N=5,663), and an unclassified group (N=7,345), respectively. Overall, 33% of the patients with diabetes were identified as obese (type 2 diabetes: 34%, type 1 diabetes: 20%, unclassified: 38%). Affirming descriptive analyses, the generalized gamma regression models revealed that obesity is associated with significant increments in health care costs regardless of type of diabetes (type 2 diabetes: € 454, type 1 diabetes: € 812, unclassified: € 532). The interaction of obesity and macro-vascular complications was numerically stronger in type 1 than in type 2 diabetes but reached statistical significance only in type 2 diabetes (and the unclassified group). Moreover, concurrent macro- and micro-vascular complications were associated with higher incremental costs in all groups. Concomitant obesity is independently associated with incremental health care costs in adult patients with type 2 diabetes and, even more so, type 1 diabetes. Results are discussed with respect to the fact that in this sample, concurrent micro- and macro-vascular complications were more frequent in type 1 diabetes. At any rate, in light of these health care costs, obesity seems relevant in both types of diabetes. Due to claims data limitations, it was not possible to distinguish obesity classes based on body height and weight information. Further research should identify adiposity thresholds for increased resource consumption using both primary and secondary data.