Vitamin B 12 and metformin.

Stowers, J. M.; Smith, Orville A.

doi:10.1136/bmj.3.5768.246-b

Cited by 23 publications

(21 citation statements)

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“…The rate of vitamin B 12 deficiency among patients who are taking metformin is reported to approach 30% (14–16). A drug interaction between metformin and the cubilin receptor inhibits the uptake of vitamin B 12 from the distal ileum, lowering serum vitamin B 12 levels.…”

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confidence: 99%

Increased Risk of Cognitive Impairment in Patients With Diabetes Is Associated With Metformin

et al. 2013

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OBJECTIVETo investigate the associations of metformin, serum vitamin B12, calcium supplements, and cognitive impairment in patients with diabetes.RESEARCH DESIGN AND METHODSParticipants were recruited from the Primary Research in Memory (PRIME) clinics study, the Australian Imaging, Biomarkers and Lifestyle (AIBL) study of aging, and the Barwon region of southeastern Australia. Patients with Alzheimer disease (AD) (n = 480) or mild cognitive impairment (n = 187) and those who were cognitively intact (n = 687) were included; patients with stroke or with neurodegenerative diseases other than AD were excluded. Subgroup analyses were performed for participants who had either type 2 diabetes (n = 104) or impaired glucose tolerance (n = 22).RESULTSParticipants with diabetes (n = 126) had worse cognitive performance than participants who did not have diabetes (n = 1,228; adjusted odds ratio 1.51 [95% CI 1.03–2.21]). Among participants with diabetes, worse cognitive performance was associated with metformin use (2.23 [1.05–4.75]). After adjusting for age, sex, level of education, history of depression, serum vitamin B12, and metformin use, participants with diabetes who were taking calcium supplements had better cognitive performance (0.41 [0.19–0.92]).CONCLUSIONSMetformin use was associated with impaired cognitive performance. Vitamin B12 and calcium supplements may alleviate metformin-induced vitamin B12 deficiency and were associated with better cognitive outcomes. Prospective trials are warranted to assess the beneficial effects of vitamin B12 and calcium use on cognition in older people with diabetes who are taking metformin.

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Increased Risk of Cognitive Impairment in Patients With Diabetes Is Associated With Metformin

et al. 2013

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“…The Hcy-increasing effect of metformin has been ascribed to the inhibition of vitamin B12 absorption and hence decreased intracellular levels of vitamin B12. 20 – 26 However, metformin also seems to reduce serum folate levels. 27 …”

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Folate status in type 2 diabetic patients with and without retinopathy

Malaguarnera¹,

Gagliano²,

Salomone³

et al. 2015

OPTH

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BackgroundFolate deficiency is associated with cardiovascular disease, megaloblastic anemia, and with hyperhomocysteinemia. This study has been undertaken to investigate the role of folate status during the progression of the diabetic retinopathy.MethodsWe measured the plasma levels of homocysteine, folic acid, and red cell folate in 70 diabetic type 2 patients with nonproliferative diabetic retinopathy (NPDR), 65 with proliferative diabetic retinopathy (PDR), 96 without diabetic retinopathy, and 80 healthy subjects used as a control group.ResultsWe found higher plasma levels of homocysteine in the NPDR group compared to the control group (P<0.001) and in the PDR group compared to control group (P<0.001) and NPDR group (P<0.01). The severity of diabetic retinopathy was associated with lower folic acid and red cell folate levels, and a significant difference was observed between PDR and NPDR groups (P<0.05).ConclusionThe folate status could play a role in the development and progression of diabetic retinopathy.

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“…For example, many diabetic patients are treated with metformin, a medication that lowers serum vitamin B 12 levels [1][2][3][4] and is associated with vitamin B 12 deficiency. 1,[5][6][7][8] In addition, almost half of all diabetic patients are older than 60, an age group in which the prevalence of metabolically confirmed B 12 deficiency ranges from 12% to 23%. 9 -11 Because of these risk factors, defining the prevalence in the diabetic population may help determine whether primary care physicians should consider screening for B 12 deficiency in diabetic patients.…”

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The Prevalence of Vitamin B12 Deficiency in Patients with Type 2 Diabetes: A Cross-Sectional Study

Pflipsen¹,

Oh²,

Saguil³

et al. 2009

The Journal of the American Board of Family Medicine

161

134

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Purpose: The purpose of this study is to define the prevalence of vitamin B 12 deficiency in a type 2 diabetic population within a primary care practice. Metformin use and advanced age are associated with vitamin B 12 deficiency and often present in type 2 diabetic patients, yet the prevalence of vitamin B 12 deficiency in the diabetic population is unknown.Methods: We conducted a cross-sectional study of 203 outpatient type 2 diabetic patients at a large military primary care clinic. Patients completed a survey and had B 12 levels measured. Patients with borderline B 12 levels also had methylmalonic acid and homocysteine levels drawn. Serum B 12 levels <100 pg/mL or serum B 12 levels of 100 to 350 pg/mL with elevation of serum methylmalonic acid >243 nmol/L or homocysteine >11.9 nmol/L defined B 12 deficiency. Descriptive statistics described frequency and means.2 and student's t tests were used to analyze associations between categorical and continuous variables, respectively. Multivariate logistical regression identified covariates independently associated with B 12 deficiency.Results: Twenty-two percent (n ‫؍‬ 44) of diabetic patients had metabolically confirmed B 12 deficiency. Patients on metformin had lower serum B 12 levels (425.99 pg/mL vs 527.49 pg/mL; P ‫؍‬ .012) and were at increased risk for B 12 deficiency (P ‫؍‬ .04), as defined by a serum B 12 level <350 pg/mL. Prevalence of B 12 deficiency was significantly lower for patients using a multivitamin (odds ratio, 0.31; 95% CI, 0.15-0.63).Conclusions :

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Vitamin B 12 and metformin.

Cited by 23 publications

References 1 publication

Increased Risk of Cognitive Impairment in Patients With Diabetes Is Associated With Metformin

Increased Risk of Cognitive Impairment in Patients With Diabetes Is Associated With Metformin

Folate status in type 2 diabetic patients with and without retinopathy

The Prevalence of Vitamin B12 Deficiency in Patients with Type 2 Diabetes: A Cross-Sectional Study

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Vitamin B 12 and metformin.

Cited by 23 publications

References 1 publication

Increased Risk of Cognitive Impairment in Patients With Diabetes Is Associated With Metformin

Increased Risk of Cognitive Impairment in Patients With Diabetes Is Associated With Metformin

Folate status in type 2 diabetic patients with&nbsp;and without retinopathy

The Prevalence of Vitamin B12 Deficiency in Patients with Type 2 Diabetes: A Cross-Sectional Study

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Folate status in type 2 diabetic patients with and without retinopathy