You must get the numerical result of the B12 because lab ranges for this are outdated, and doctors follow the old numbers which are very low (and still called normal). If you don't live in the US we need the concentration as some countries report differently and that changes the numbers too.

Simvastatin is a known PN causer. We discuss this on PN forum.
We have posters who were damaged by this drug:
http://neurotalk.psychcentral.com/post665830-5.html
This link is only a beginning.
Search Dr. Beatrice Golomb MD who specializes in statin toxicity and also Jay Cohen MD, and Dr. Graveline MD who is a doctor himself and former astronaut.

Statins also cause diabetes you know. That information was released rather recently. Also implicated is damage to memory and brain. Dr. Graveline lost his memory on Lipitor and wrote a book about it.

Metformin will disrupt B12 in many patients. So the B12 level you have now is very important. Eating well is not going to work when a drug is doing mischief in your body.

All people on statins should be taking CoQ-10... this is made in our bodies and is blocked by the statins. When this is low, muscles suffer and esp heart muscle can become weak. Over time you may develop congestive heart failure or cardiomyopathy.

If you continue with statins, you can expect to become worse. Nothing we have here in the research to help diabetics will help you nerve-wise when you take the statins. It is a tough decision for you, and only you can make it. I only provide the data that is mounting today about this subject.

Typical RX treatments for PN are gabapentin/Lyrica, Cymbalta or other SSRIs, tricyclic antidepressants (which are more helpful than the others), Namenda (for difficult patients not responding) and various pain medications.