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Increased intake of calcium reverses vitamin B12 malabsorption induced by metformin.

Abstract

OBJECTIVE

Of patients who are prescribed metformin, 10-30% have evidence of reduced vitamin B12 absorption. B12-intrinsic factor complex uptake by ileal cell surface receptors is known to be a process dependent on calcium availability Metformin affects calcium-dependent membrane action. The objective of this study was to determine the magnitude and mechanism of the reduction in serum vitamin B12 after metformin administration.

RESEARCH DESIGN AND METHODS

A comparative study design was employed using 2 groups (metformin and control). A total of 21 patients with type 2 diabetes received sulfonylurea therapy; 14 of these 21 patients were switched to metformin. Monthly serum total vitamin B12 measurements and holotranscobalamin (holoTCII) (B12-TCII) were performed. After 3 months of metformin therapy, oral calcium supplementation was administered.

RESULTS

Serial serum vitamin B12 determinations revealed a similar decline in vitamin B12 and holoTCII. Oral calcium supplementation reversed the metformin-induced serum holoTCII depression.

CONCLUSIONS

Patients receiving metformin have diminished B12 absorption and low serum total vitamin B12 and TCII-B12 levels because of a calcium-dependent ileal membrane antagonism, an effect reversed with supplemental calcium.

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  • Authors+Show Affiliations

    ,

    Department of Medicine, Mount Sinai School of Medicine, New York, USA. bauman.william@bronx.va.gov

    , , ,

    Source

    Diabetes care 23:9 2000 Sep pg 1227-31

    MeSH

    Adult
    Calcium Carbonate
    Calcium, Dietary
    Dietary Supplements
    Ethnic Groups
    Humans
    Hypoglycemic Agents
    Intestinal Absorption
    Male
    Metformin
    Middle Aged
    Vitamin B 12

    Pub Type(s)

    Clinical Trial
    Controlled Clinical Trial
    Journal Article
    Research Support, Non-U.S. Gov't
    Research Support, U.S. Gov't, Non-P.H.S.

    Language

    eng

    PubMed ID

    10977010

    Citation

    Bauman, W A., et al. "Increased Intake of Calcium Reverses Vitamin B12 Malabsorption Induced By Metformin." Diabetes Care, vol. 23, no. 9, 2000, pp. 1227-31.
    Bauman WA, Shaw S, Jayatilleke E, et al. Increased intake of calcium reverses vitamin B12 malabsorption induced by metformin. Diabetes Care. 2000;23(9):1227-31.
    Bauman, W. A., Shaw, S., Jayatilleke, E., Spungen, A. M., & Herbert, V. (2000). Increased intake of calcium reverses vitamin B12 malabsorption induced by metformin. Diabetes Care, 23(9), pp. 1227-31.
    Bauman WA, et al. Increased Intake of Calcium Reverses Vitamin B12 Malabsorption Induced By Metformin. Diabetes Care. 2000;23(9):1227-31. PubMed PMID: 10977010.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Increased intake of calcium reverses vitamin B12 malabsorption induced by metformin. AU - Bauman,W A, AU - Shaw,S, AU - Jayatilleke,E, AU - Spungen,A M, AU - Herbert,V, PY - 2000/9/8/pubmed PY - 2001/2/28/medline PY - 2000/9/8/entrez SP - 1227 EP - 31 JF - Diabetes care JO - Diabetes Care VL - 23 IS - 9 N2 - OBJECTIVE: Of patients who are prescribed metformin, 10-30% have evidence of reduced vitamin B12 absorption. B12-intrinsic factor complex uptake by ileal cell surface receptors is known to be a process dependent on calcium availability Metformin affects calcium-dependent membrane action. The objective of this study was to determine the magnitude and mechanism of the reduction in serum vitamin B12 after metformin administration. RESEARCH DESIGN AND METHODS: A comparative study design was employed using 2 groups (metformin and control). A total of 21 patients with type 2 diabetes received sulfonylurea therapy; 14 of these 21 patients were switched to metformin. Monthly serum total vitamin B12 measurements and holotranscobalamin (holoTCII) (B12-TCII) were performed. After 3 months of metformin therapy, oral calcium supplementation was administered. RESULTS: Serial serum vitamin B12 determinations revealed a similar decline in vitamin B12 and holoTCII. Oral calcium supplementation reversed the metformin-induced serum holoTCII depression. CONCLUSIONS: Patients receiving metformin have diminished B12 absorption and low serum total vitamin B12 and TCII-B12 levels because of a calcium-dependent ileal membrane antagonism, an effect reversed with supplemental calcium. SN - 0149-5992 UR - https://www.unboundmedicine.com/medline/citation/10977010/full_citation L2 - http://care.diabetesjournals.org/cgi/pmidlookup?view=long&pmid=10977010 DB - PRIME DP - Unbound Medicine ER -