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- Title
Long-term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study.
- Authors
Aroda, Vanita R; Edelstein, Sharon L; Goldberg, Ronald B; Knowler, William C; Marcovina, Santica M; Orchard, Trevor J; Bray, George A; Schade, David S; Temprosa, Marinella G; White, Neil H; Crandall, Jill P; Diabetes Prevention Program Research Group
- Abstract
<bold>Context: </bold>Vitamin B12 deficiency may occur with metformin treatment, but few studies have assessed risk with long-term use.<bold>Objective: </bold>To assess the risk of B12 deficiency with metformin use in the Diabetes Prevention Program (DPP)/DPP Outcomes Study (DPPOS).<bold>Design: </bold>Secondary analysis from the DPP/DPPOS. Participants were assigned to the placebo group (PLA) (n = 1082) or the metformin group (MET) (n = 1073) for 3.2 years; subjects in the metformin group received open-label metformin for an additional 9 years.<bold>Setting: </bold>Twenty-seven study centers in the United States.<bold>Patients: </bold>DPP eligibility criteria were: elevated fasting glucose, impaired glucose tolerance, and overweight/obesity. The analytic population comprised participants with available stored samples. B12 levels were assessed at 5 years (n = 857, n = 858) and 13 years (n = 756, n = 764) in PLA and MET, respectively.<bold>Intervention: </bold>Metformin 850 mg twice daily vs placebo (DPP), and open-label metformin in the metformin group (DPPOS).<bold>Main Outcome Measures: </bold>B12 deficiency, anemia, and peripheral neuropathy.<bold>Results: </bold>Low B12 (≤ 203 pg/mL) occurred more often in MET than PLA at 5 years (4.3 vs 2.3%; P = .02) but not at 13 years (7.4 vs 5.4%; P = .12). Combined low and borderline-low B12 (≤ 298 pg/mL) was more common in MET at 5 years (19.1 vs 9.5%; P < .01) and 13 years (20.3 vs 15.6%; P = .02). Years of metformin use were associated with increased risk of B12 deficiency (odds ratio, B12 deficiency/year metformin use, 1.13; 95% confidence interval, 1.06–1.20). Anemia prevalence was higher in MET, but did not differ by B12 status. Neuropathy prevalence was higher in MET with low B12 levels.<bold>Conclusions: </bold>Long-term use of metformin in DPPOS was associated with biochemical B12 deficiency and anemia. Routine testing of vitamin B12 levels in metformin-treated patients should be considered.
- Publication
Journal of Clinical Endocrinology & Metabolism, 2016, Vol 101, Issue 4, p1754
- ISSN
0021-972X
- Publication type
journal article
- DOI
10.1210/jc.2015-3754