Risk factors for Vitamin B12 deficiency in type 2 diabetes patients treated with Metformin

Abstract

Background: Vitamin B12 deficiency has serious health consequences, including macrocytic anemia and neurological disorders that may lead to dementia.There are multiple causes of deficiency, including treatment with metformin.

Aim: To determine the prevalence of vitamin B12 deficiency in a sample of patients with type 2 diabetes who treated with metformin, and identifying risk factors for this deficiency.

Materials and methods: This cross-sectional study included 120 Syrian patients with type 2 diabetes mellitus treated with metformin in the Endocrinology and Metabolism Division of Al-Assad University Hospital in Damascus, Syria. The study included measuring vitamin B12 levels and identifying risk factors for its deficiency which defined as a concentration less than 150 pg/ml, using multiple logistic regressions.

Results: The prevalence of vitamin B12 deficiency among patients with type 2 diabetes treated with metformin was 18.3% (22 patients). It was 24.2% among patients ≥ 70 years old and 16.15 in younger age. Metformin use for more than 15 years showed an increased risk of vitamin B12 deficiency (OR 6.11, 95% CI: 1.82 – 20.4) (P = 0.003).‏Compared with a daily metformin dose of <1000 mg, the adjusted odds ratios for a daily metformin dose of 1000-2000 and >2000 mg were 2.22 (P = 0.318).

Conclusion: The use of metformin in patients with type 2 diabetes is associated with vitamin B12 deficiency. The probability of this deficiency increases in older patients and, using high-dose metformin (>2000 mg/day) for longer duration.

Keywords: Diabetes Mellitus, Metformin, Vitamin B12