Type 2 Diabetes Severity Modifies Long-Term Health Expenditures After Metabolic Bariatric Surgery.

INTRODUCTION: Metabolic bariatric surgery (MBS) lowers long-term health expenditures among patients with type 2 diabetes (T2D). MBS resources are scarce however, and it is unknown which subgroups of patients with diabetes are most likely to see reduced expenditures. METHODS: We conducted stratified analyses of total, medication, outpatient, and inpatient expenditures from 3 years pre- to 5.5 years post-MBS in a retrospective cohort study of 6,657 patients with T2D and obesity from 2012 to 2019 and 19,059 matched non-surgical patients. Patients were stratified into three groups based on diabetes severity, using the validated Advanced-DiaRem measure. Advanced-DiaRem scores range from 0 to 21, with higher scores indicating greater severity. Expenditures were estimated in 6-month intervals and analyzed using generalized linear models. RESULTS: Patients with high Advanced-DiaRem scores (13–21) had higher hemoglobin A1c, greater insulin use, and longer diabetes duration compared to those with moderate (8–12) and low scores (0–7). In the 6 months pre-surgery, patients with high scores had higher mean total expenditures (US$6,418 non-surgical, $6,896 surgical) than patients with moderate scores ($4,332 non-surgical, $5,373 surgical) and low scores ($2,995 non-surgical, $3,469 surgical). Post-MBS, estimated total expenditures for surgical patients declined across all Advanced-DiaRem subgroups, with the greatest reductions observed in patients with high scores. At 5.5 years post-surgery, total expenditures for surgical patients were $1,240/6-months lower than for non-surgical patients (95% confidence interval 679, 1,771). Savings were mainly driven by reduced medication expenditures. CONCLUSIONS: Expenditure reductions after MBS in patients with T2D appear to be driven by those with high-severity diabetes.