10 Unexpected Metformin Side Effects Few Patients Expect to Notice After Long-Term Use

 5. Tingling or Numbness in Hands and Feet
You may notice pins-and-needles sensations at night from metformin side effects or a dull numbness in toes that was not there before. Long-term metformin side effects have been linked to B12 deficiency in research making nerve sensations appear gradually and easy to rationalize away. The worry and reduced confidence from metformin side effects like this can limit activities you once enjoyed without hesitation.

But nerve signals are not the only quiet change from metformin side effects.