The changing cost to prevent diabetes: A retrospective analysis of the Diabetes Prevention Program.

Objectives: Diabetes prevention interventions are poorly implemented. While health care costs generally increase, 2 factors affect the relative cost of diabetes prevention interventions: the declining cost of metformin (even without insurance) and the new recommendation for vitamin B12 monitoring during metformin treatment. The study's objective was to update the relative health system cost estimate of metformin for diabetes prevention by incorporating the current health system cost of metformin and the cost of addressing potential metformin-associated vitamin B12 deficiency. The study was designed to assess whether metformin with vitamin B12 supplementation is a cost-saving measure for diabetes prevention and for the updated cost estimate to be useful in assessing future implementation studies.

Methods: In 2012, the Diabetes Prevention Program Research Group published detailed per capita total direct health system costs for the Diabetes Prevention Program (DPP) and the Diabetes Prevention Program Outcomes Study (DPPOS). The present analysis incorporated the declining cost of metformin and the increasing cost of metformin monitoring into the detailed per capita health system costs found in the DPP and DPPOS. The updated costs were used to assess the total cost of metformin use for diabetes prevention relative to placebo and lifestyle intervention.

Results: The current health system cost to acquire metformin ranges from $0 to $72 per year. The estimated health system cost to address potential metformin-associated vitamin B12 deficiency is $28 per metformin-treated patient per year. The 10-year total health system cost for metformin in diabetes prevention can decrease by $329 or increase by $21 depending on the cost to acquire metformin. Compared with placebo, the unadjusted cost savings of metformin is generally maintained, although it may double or quadruple depending on how metformin is acquired by patients. Metformin with vitamin B12 supplementation remained less costly and less effective than lifestyle intervention.

Conclusion: Metformin is generally more cost-saving for diabetes prevention than previously reported because of decreasing costs for patients to acquire metformin. The cost savings was increased despite increased management cost associated with addressing metformin-associated vitamin B12 deficiency.