Educational screening context only — not medical advice, not a diagnosis, and not a substitute for serum B12 testing ordered by your clinician.

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0 5 10+

MUI

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Formula

MUI = (dose × years) ÷ 1000

Your regimen

mg/day
years

Enter daily dose and years on metformin.

Educational only — does not diagnose B12 deficiency.
Confirm with labs. Disclaimer.

How to use this

  • Daily dose — total metformin you take per day in milligrams (e.g. 2000 for two 1000 mg tablets).
  • Years on metformin — approximate duration of continuous use.
  • MUI > 5 — in Shivaprasad et al., higher deficiency odds; discuss serum B12 screening (± MMA if borderline) with your clinician. This tool does not diagnose deficiency.

Evidence context

This index comes from cohort work on metformin-associated B12 deficiency. ADA still recommends periodic B12 assessment after about 4–5 years on metformin, or sooner with anemia, neuropathy, dyspeptic symptoms, prior GI surgery, vegan diet, PPI use, or age 65+.

From this tool

Dose registry