Deficit of vitamin B12 in diabetics on metformin: a cross-sectional study
DOI:
https://doi.org/10.32385/rpmgf.v40i6.13675Keywords:
Vitamin B12 deficiency, Metformin, Peripheral neuropathyAbstract
Introduction: Type 2 diabetes affects about 13.3% of the Portuguese population. Metformin was for many years considered first-line pharmacology in diabetes and is currently still recommended as such in diabetics without cardiorenal comorbidities. Up to 30% of diabetics on metformin have vitamin B12 deficiency, which can manifest as potentially irreversible neuropathy, mimicking diabetic neuropathy. Periodic dosing of vitamin B12 is recommended in several bibliographic sources, however there is no consensus on its methodology.
Objectives: We aim to identify the prevalence of vitamin B12 deficiency in patients undergoing metformin therapy and its relationship with other variables, reducing avoidable comorbidities and contributing to developing more precise therapeutic and medical guidelines.
Methods: This work consists of a cross-sectional study. The medical team of a primary healthcare unit attended a clinical session about the importance of measuring the blood levels of vitamin B12 in patients with type 2 diabetes under metformin. Inclusion criteria: adults diagnosed with type 2 diabetes treated with metformin. Exclusion criteria: history of bariatric surgery, diagnosis of pernicious anemia, and diagnosis of malabsorptive syndrome. Variables analyzed: vitamin B12 serum levels, proportion of deficit, symptomatology, duration of treatment with metformin, dose of metformin used, simultaneous therapy with proton pump inhibitors, and concurrent diagnosis of hypothyroidism.
Results: Over 20 months, vitamin B12 measurements of 362 diabetic patients on metformin were requested. Of these, 58 patients (18.02%) showed a deficit and only six patients with B12 deficit presented symptoms. All individuals with a deficit had been using metformin for 6 years or more and the more commonly used dose of metformin in the population with deficit was 2000mg/day.
Conclusions: This periodic measurement allows early correction of possible deficits and avoids their consequences, such as the development of a potentially irreversible neuropathy in diabetic patients, a population already holding great frailty.
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