[Vitamin B12 deficiency associated with high doses od metformin in older people diabetic]

The aim of the study was to estimate if B12 deficiency is associated with the use of metformin in the elderly diabetics.

Case-control study in diabetic OP. Cases (n = 137) were defined as elderly with B12 < 221 pmol/L and controls (n = 279) elderly with B12 > 221 pmol/L. Four categories of metformin use were defined: non-users, ≤850 mg/day, > 850 and < 2,550 mg/day and ≥2,550 mg/day. Metformin ≥2,550 mg/day was high doses considered. The crude OR for B12 deficiency and consumption of Metformin were calculated. Logistic regression models were developed to explore the association between B12 deficiency and metformin dose. The research protocol was approved by the Ethics Committee of INTA.

The age of cases and controls was (70.2 years vs 68.6 years (p < 0.05). The 62% were women in cases vs 74.9% in controls (p < 0.05). The 73% of cases and 76% of controls used metformin (p < 0.05) the average consumption of metformin was de 1,954.3 mg/day (SD: 1,063.2) in cases and 1,696.6 mg/day (SD: 1,074.4) in controls (p < 0.05). The use of 2,550 mg/day was observed in 29.2% of cases and 19.3% for controls (p < 0.05). It was observed that OP who consumed high doses of metformin had 1.9 times the risk of B12 deficiency (OR: 1.9; 95%CI: 1,08- 3,30).

These results show a strong association between high doses of metformin and low levels of vitamin B12 in diabetic elderly. This project was funded by FONIS SA11I2092.