Does Metformin deplete any vitamins over time?

Asked by giggz · 1 day, 20 hours ago · 13 views

I have been on Metformin for 4 years for Type 2 diabetes. Lately I have been feeling more tired than usual and having some numbness in my feet. Could this be related to my medication affecting my nutrition?

giggz · 1 day, 11 hours ago

The symptoms you are describing — fatigue and peripheral numbness — are classic presentations of Vitamin B12 deficiency, & Metformin is a well-established cause. This connection has been documented in the medical literature for decades but is chronically underemphasized at the point of prescribing. The mechanism: Metformin interferes with calcium-dependent absorption of Vitamin B12 in the terminal ileum. It does not reduce B12 intake — it reduces how much your body can absorb from food. The effect accumulates over time, which is why you are noticing symptoms after four years rather than immediately. Studies suggest approximately 30% of long-term Metformin users develop clinically significant B12 deficiency. B12 is essential for myelin sheath production — the protective coating around nerve fibers. Deficiency causes the peripheral neuropathy symptoms you describe (numbness, tingling, especially in the feet) and also contributes to fatigue, cognitive fog, and anemia. Critically, if left untreated, B12 deficiency neuropathy can become permanent even after supplementation restores blood levels. The ADA 2025 Standards of Care recommend periodic B12 monitoring for all long-term Metformin users. Request a serum B12 level at your next appointment. If deficient, your physician will likely recommend B12 supplementation — methylcobalamin is preferred over cyanocobalamin for neurological symptoms. Dietary B12 from eggs, fish, dairy, and meat helps but may not be sufficient given the absorption impairment. Platelytix flags the Metformin-B12 interaction automatically and notes it when analyzing meals low in B12-rich foods.