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14-09-2009 | Diabetes | Article

One fifth of Type 2 diabetes patients have vitamin B12 deficiency


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MedWire News: Vitamin B12 deficiency is present in 22% of patients with Type 2 diabetes, researchers report.

Vitamin B12 deficiency can lead to nerve symptoms similar to that of diabetic peripheral neuropathy. However, although many patients with diabetes are at risk for vitamin B12 deficiency as a natural consequence of aging and as a result of treatment with metformin, the prevalence of the condition in this population was previously unknown.

In a cross-sectional study, Matthew Pflipsen (Raymond W Bliss Army Health Center, Fort Huachuca, Arizona, USA) and co-workers measured vitamin B12 levels in 203 outpatients with Type 2 diabetes at a large military primary care clinic.

Vitamin B12 deficiency was defined as serum B12 levels of less than 100 pg/ml, or serum B12 levels of 100 to 350 pg/ml with levels of serum methylmalonic acid greater than 243 nmol/l or levels of homocysteine greater than 11.9 nmol/l.

“Elevated methylmalonic acid and homocysteine levels improve the diagnosis of tissue B12 deficiency and may identify patients with deficiency at an early, reversible stage,” explain the authors.

One patient had a B12 level less than 100 pg/ml, and 43 patients with intermediate B12 levels had elevations of either methylmalonic acid or homocysteine, resulting in a total of 44 patients (22%) diagnosed with metabolic B12 deficiency.

Patients using metformin had lower B12 levels, but metformin use was not associated with overt B12 deficiency. The majority of patients were taking metformin and approximately half were on a dose of at least 2 g per day at the time of enrolment.

Just over half the patients in the study were taking a daily multivitamin tablet. In multivariate analysis, multivitamin use seemed to protect patients from B12 deficiency.

Other factors associated with increased risk for B12 deficiency, such as advanced age and use of proton pump inhibitors, were not significantly associated with B12 deficiency.

The authors suggest that physicians should consider the comorbid effects of vitamin B12 deficiency in a population already predisposed to neuropathic complications.

“Further studies need to be undertaken to determine whether screening and subsequent treatment can prevent peripheral neuropathy from developing in patients with Type 2 diabetes before advocating for universal screening,” the researchers conclude in the Journal of the American Board of Family Medicine.

“Multivitamin should also be explored as a method for reducing the incidence of B12 deficiency in the Type 2 diabetic population” they add.

MedWire ( is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009

By Jenny Grice