Association Between Weight Change, Clinical Outcomes, and Health Care Costs in Patients with Type 2 Diabetes

BACKGROUND: Previous research suggests that weight loss is associated with decreases in health care costs among individuals with type 2 diabetes mellitus (T2DM) and that weight change can affect clinical measures, including hemoglobin A1c (A1c), low-density lipoprotein cholesterol (LDLC), and blood pressure. Previous research has also demonstrated more pronounced impact of weight change among patients with T2DM who are obese and have no evidence of cardiovascular disease (CVD). OBJECTIVES: To (a) examine the association between weight change and all-cause and diabetes-related health care costs among patients with T2DM; (b) examine the association between weight change and select clinical measures among patients with T2DM; and (c) analyze a subgroup of obese patients with no previous CVD. METHODS: This retrospective, observational cohort study used U.S. insurance claims linked to laboratory and electronic medical records. This study included patients with T2DM aged 18 years or older who added or switched to a nonmetformin antidiabetes medication after metformin monotherapy between January 1, 2007, and June 30, 2012 (date of add/switch was the index date). The primary predictor was percentage weight change (PWC) between a weight measurement at index and a follow-up measurement 6 months later; PWC ranged from negative (weight loss) to positive (weight gain). Outcomes, measured in the 12-month period beginning at the time of follow-up weight measurement, included all-cause and diabetes-related health care costs and achievement of thresholds for A1c, blood pressure, and LDL-C. Multivariable models quantified the association between PWC (linear effect) and study outcomes. RESULTS: A total of 1,520 patients (mean age 55 years; 47% female) were included, with 780 patients (mean age 53 years; 51% female) in the subgroup sample. Mean (SD) index weight and PWC were 224.6 (52.8) lbs and +0.2% (4.7%) in the primary analysis, and 241.3 (47.3) lbs and -0.2% (4.6%) in the subgroup sample. In adjusted analyses, decreasing PWC was associated with decreasing diabetes-specific pharmacy costs (P < 0.001) in the primary analysis sample and with decreasing all-cause pharmacy costs (P = 0.018), diabetes-specific total costs (P = 0.039), diabetes-specific medical costs (P = 0.002), and diabetes-specific pharmacy costs (P < 0.001) in the subgroup sample. PWC was not associated with all-cause total health care costs or all-cause medical costs in either sample. In adjusted analyses, decreasing PWC was also associated with increasing odds of attaining the A1c goals of < 6.5% (P < 0.001) and < 7.0% (P < 0.001) in the primary analysis sample and increasing odds of attaining the A1c goals of < 6.5% (P < 0.001), < 7.0% (P < 0.001), and < 8.0% (P = 0.010) in the subgroup sample. PWC was not associated with any of the other clinical measures in either of the study samples. CONCLUSIONS: This real-world study suggests that among patients with T2DM, weight loss over a short-term (6-month) period is associated with positive impact on attainment of A1c goals and decreased diabetes-specific pharmacy costs over the subsequent 12 months. In the subset of patients who were obese and had no previus CVD, weight loss over the 6-month period was also associated with decreased all-cause pharmacy costs, diabetes-specific medical costs, and diabetes-specific total health care costs. Future research is warranted to examine whether these associations change over longer-term periods of follow-up.