The reason why you should take B12 with metformin is because when you take metformin, the metformin reduces the body's ability to absorb the essential vitamin B12 nutrient in your intestines.
And then over time, the malabsorption of the B12 can result in a B12 deficiency, which results in severe fatigue, memory loss and even irreversible nerve damage.
The combination of taking B12 with metformin is crucial for preventing nerve damage, preventing impaired absorption and avoiding anemia.
Metformin also interferes with how the small intestine absorbs the B12, and often does so by altering the calcium dependent binding or your gut's bacterial environment.
B12 is also vital for proper nerve health.
A deficiency in B12 also causes peripheral neuropathy (numbness and tingling).
And because this overlaps heavily with diabetic neuropathy, a B12 deficiency can also go misdiagnosed, which can lead to permanent nerve damage.
Also low B12 levels in the body reduce the production of healthy red blood cells and cause megaloblastic anemia, which also makes you feel short of breath and constantly weak.
Symptoms of low B12 levels with metformin, include extreme fatigue, "pins and needles" sensations in the hands and feet, memory issues, and a sore, red tongue.
Because these symptoms also mimic diabetic neuropathy, routine blood testing is highly recommended.
Prolonged metformin use (especially over a period of 5 years) or high dosages increase the risk of developing low vitamin B12 levels.
Common symptoms to watch out for when taking metformin include.
Neurological changes like numbness or tingling, (pins and needles feeling) in your hands and feet as well as balance or walking difficulties, and loss of reflexes.
Cognitive issues like brain fog, poor memory performance, confusion, depression or mood changes.
Fatigue and weakness, like extreme tiredness, a constant lack of energy, muscle weakness and dizziness.
Mouth and tongue problems, a sore, red or swollen tongue also known as glossitis and mouth ulcers.
And signs of anemia such as pale or slightly jaundiced (yellow) skin and a fast or irregular heartbeat.