The cost-effectiveness of vitamin D supplementation for the prevention of type 2 diabetes in the United States: a microsimulation modelling study

Background Vitamin D lowers the risk of type 2 diabetes in adults with prediabetes. We assessed the long-term cost-effectiveness of vitamin D supplementation for preventing type 2 diabetes. Methods We applied a validated microsimulation model to estimate long-term health and economic consequences of vitamin D in a representative cohort of 10,000 U.S. adults with prediabetes in the National Health and Nutrition Examination Survey (NHANES) 2013–2018 cohort. Treatment effects came from individual-participant data of three randomised trials of vitamin D versus placebo (D2d, USA, 2013–2018; DPVD, Japan, 2013–2019; Tromsø, Norway, 2008–2015; pooled analysis 2023). Cost-effectiveness was measured by an incremental cost-effectiveness ratio (ICER) in terms of cost per quality-adjusted life year (QALY) compared to no vitamin D. We conducted subgroup analyses by age, baseline fasting glucose level, body weight, and family history of diabetes. We performed one-way and probabilistic sensitivity analysis. Costs were in 2024 U.S. dollars. 10-year and lifetime time horizons were studied from a U.S. health care system perspective. Findings In a NHANES-derived cohort of 4176 adults with prediabetes (mean age 53.3 years [SD 17.0]; 2024 [49%] female; 2603 [62%] non-Hispanic White, 488 [12%] non-Hispanic Black, 668 [16%] Hispanic, 417 [10%] other race/ethnicity), vitamin D supplementation reduced per-person lifetime costs by $3208 (95% uncertainty interval [UI] −$5974 to $171), increased lifetime QALYs by 0.12 (95% UI 0.05–0.19), and yielded a lifetime net monetary benefit of $15,483 (95% UI $8108–$21,907) at a willingness-to-pay threshold of $100,000/QALY. Life-years gained were 0.27 per person (95% UI 0.06–0.50). Vitamin D reduced the lifetime cumulative incidence of diabetes by 8% (95% UI 6.4–10.6%). Diabetes complications were reduced by an average of 6.4% (95% UI 3.2–8.7%). There were little differences in ICERs across subgroups. Changes in intervention-related parameters had limited effects on the cost-effectiveness ratios across sensitivity analyses, and the intervention likewise remained cost-saving compared to no vitamin D under all simulation scenarios. Interpretation Vitamin D supplementation may be an efficient use of health care resources for preventing type 2 diabetes in adults with prediabetes. Funding Research Ireland (Grant Number: EPSPD/2022/165).