Abdul Mannan: Why Your Patient on Metformin is Losing B12
Abdul Mannan, Consultant Haematologist at Betsi Cadwaladr University Health Board, shared on LinkedIn:
”Why Your Patient on Metformin is Losing B12 (And Why It Matters)
When we prescribe metformin, we’re usually thinking about glucose control.
But here’s something that often slips past us: many of our patients on long-term metformin develop B12 deficiency—and the mechanism is worth understanding. It’s not just poor diet.
Metformin disrupts how the terminal ileum absorbs the B12-Intrinsic Factor complex.
The calcium-dependent uptake at the cubilin receptor gets blocked, leaving B12 to pass right through unabsorbed.
But there’s more.
Our livers continuously recycle B12 through bile into the intestine, where it gets reabsorbed. Metformin closes that door too.
So patients face a double hit: less absorption from food, plus a leak of recycled B12 into the stool.
The timing matters.
This isn’t immediate.
Stores deplete gradually, which is why symptoms can sneak up. We might see fatigue first, sometimes confused with diabetic neuropathy, sometimes missed as anaemia.
The practical take?
For patients on metformin long-term, consider B12 screening.
Some evidence supports calcium supplementation, and for others, intramuscular B12 works when dietary approaches fall short.
It’s one of those interactions that changes how you approach your diabetic patients in haematology clinic.”
Stay updated with Hemostasis Today.
-
Jun 2, 2026, 15:28Kabilan K. L.: Management and Diagnosis of Acute Coronary Syndrome Types
-
Jun 2, 2026, 15:26Mital Jhaveri: What New Data Reveal About DOACs and Androgen Receptor Inhibitors?
-
Jun 2, 2026, 15:22Dhananjaya Kotebagilu Narayana Vamyanmane: High-Resolution Ultrasound Evaluation of Bowel Wall Ischemia
-
Jun 2, 2026, 15:20Joep Schellens: Influence of Dexamethasone and Tocilizumab on Fibrinolysis in COVID-19
-
Jun 2, 2026, 15:12Ebrahim Umer: The Sickest Liver Patients Deserve One Language – Lessons from the Kyoto Consensus
-
Jun 2, 2026, 15:10Ney Carter Borges: Bempedoic Acid and Venous Thromboembolism Risk in Statin-Intolerant Patients
-
Jun 2, 2026, 15:07Sayan Koley: Coagulation Science – Where Precision Saves Lives
-
Jun 2, 2026, 15:04Ahmed Mohsen: Low CHA₂DS₂-VA Score Does Not Always Mean No Anticoagulation
-
Jun 2, 2026, 15:04The Risk Factors and Optimal Prevention Strategies of VTE in Sickle Cell Disease – RPTH Journal