Introduction:

Metformin is the first-line drug in type 2 diabetes. However, it has been described that it produces a decrease in vitamin B12 plasma levels.

Objective:

To determine factors associated with vitamin B12 deficiency in elderly people with type 2 diabetes treated with metformin attending an outpatient clinic in a public center.

Methodology:

Observational, descriptive, cross-sectional study, with an analytical component, carried out in elderly people over 60 years of age with type 2 diabetes treated with metformin, in the outpatient clinic of the Santo Domingo Complex, Asuncion, Paraguay, from June to August 2024. Exclusion criteria: gastrectomy or gastric bypass, malabsorption syndrome, alcoholism, B12 supplementation, vegetarian diet, and patients who did not sign the consent form. Non-probability sampling of consecutive cases. The calculated sample size was 158. B12 deficiency was considered at values ≤203 pg/mL.

Results:

One hundred fifty-eight people aged 60 to 89 years participated, with a mean age of 73 ± 6 years, 62% were women. Sixty-seven percent met polypharmacy criteria and 21.5% consumed proton pump inhibitors. The duration of metformin use was 7.71 ± 6.53 years, with a daily dose of 1389 ± 746.22 mg. The 38.6% presented B12 deficiency, more frequent in women, polymedicated, without PPI consumption. A total of 86.7% presented hemogram alterations: anemia (18.9%), leukopenia (8.2%) and thrombocytopenia (6.3%). The mean vitamin B12 concentration was 356 ±291.11 pg/mL (range 90 - 2240 pg/mL). Statistical association was found with the time of use and dose of metformin and the use of proton pump inhibitors.

Conclusions:

The prevalence of hypovitaminosis B12 was 38.6%. Statistical association was observed with higher daily dose and longer time of metformin use, but not with older age. Based on these findings, it is recommended to actively look for hypovitaminosis B12 in older people treated with metformin.

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