Vitamin B12 levels in patients with type 2 diabetes mellitus receiving metformin: a cross-sectional study
Abstract
Background: Type 2 diabetes mellitus (T2DM) remains a global health problem. Metformin is a
first-line drug, but with long-term use it can cause vitamin B₁₂ deficiency. Metformin use is thought to
interfere with the absorption of the vitamin in the small intestine. B₁₂ deficiency has been associated
with neurological and cognitive impairment, particularly in older patients, but research remains
inconsistent. Diagnosis is difficult due to the limited information content of the serum B₁₂ level alone;
additional markers and age-related factors are suggested. Some experts consider levels below 450
pg/mL to be a relative deficiency in the presence of risk factors.
Objective: To assess the prevalence of vitamin B12 deficiency among patients with established
type 2 diabetes mellitus treated with metformin.
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Methods: This cross-sectional study was conducted at the Clinic of Internal Medicine of the S.D.
Asfendiyarov Kazakh National Medical University among 101 patients with type 2 diabetes mellitus
treated with metformin for at least 3 years. All participants had their vitamin B₁₂ levels measured once.
Data on the duration of therapy, age, and other factors potentially associated with vitamin B₁₂ deficiency
were also analyzed.
Results: The study included 101 patients with type 2 diabetes, the average age was 62 years, the
average duration of metformin therapy was 9 years. The median vitamin B₁₂ level was 450 pg/ml.
Deficiency (<200 pg/ml) was detected in 2%, insufficiency (200–300…
How strong is the evidence?
Evidence Hub reads this as a cross-sectional, done in people. Its evidence level is 4 of 5 (Low · observational). Observational designs can show an association but not prove cause. Reported size: 101 participants or records.
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