Metformin use tied to B-vitamin deficiency and cognitive dysfunction in older adults

  • Porter KM & al.
  • J Clin Endocrinol Metab
  • 28 Mar 2019

  • curated by Sarfaroj Khan
  • UK Clinical Digest
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  • Hyperglycaemia with metformin use is associated with cognitive dysfunction in older adults, suggesting that specific B-vitamin deficiencies contribute to this risk.
  • Intake of fortified food can improve the status of B-vitamin and may be helpful in maintaining cognitive function in older patients with or at risk for diabetes.

Why this matters

  • No previous research has explored the association of diabetes and use of metformin with all relevant B-vitamins.
  • Deficiencies of B-vitamins have been independently associated with cognitive dysfunction, with epidemiological studies reporting an increased risk for dementia in patients with type 2 diabetes compared with the general population.

Study design

  • This observational study used data from the Trinity, Ulster and Department of Agriculture (TUDA) cohort involving 4160 community-dwelling older people who were classified as normoglycaemic or hyperglycaemic based on glycosylated haemoglobin (HbA1c) either with or without metformin treatment.
  • Repeatable Battery for Assessment of Neuropsychological Status (RBANS) and the Frontal Assessment Battery (FAB) were used for cognitive assessments.
  • Funding: TUDA was supported by the Irish Department of Agriculture, Food and the Marine and Health Research Board.

Key results

  • Metformin use demonstrated an increased risk for deficiency of:
    • vitamin B12 (OR, 1.45; 95% CI, 1.03-2.02),
    • vitamin B6 (OR, 1.48; 95% CI, 1.02-2.15).
  • Among both hyperglycaemic cases and normoglycaemic control participants, regular fortified food intake (≥5 portions per week) significantly improved biomarker status of all-relevant B-vitamins.
  • After adjustment, metformin use was associated with higher cognitive function risk as assessed using RBANS (OR, 1.36; 95% CI, 1.03-1.80; P=.03) and FAB (OR, 1.34; 95% CI, 1.03-1.74; P=.03).


  • Results cannot confirm causal relationships of diabetes and metformin use with B-vitamin deficiency.

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