How does namenda affect insulin and/or insulin affect namenda? my wife was put on insulin in June?

Added 11 Jul 2012:

My wife has been on Namenda for 3 years now, she takes (2) 10 mg tablets daily and has never had any problems. Since she has started the insulin regiment, ( 24 units homolog for breakfast, 8 units for lunch, 10 units for supper, and 15 units of lantus solostar at bedtime) she is experiencing dizziness 2 hours after she has taken her morning Namenda . We had stopped the Namenda for 1 week to get her sugar levels down and she was not having the dizziness, when I put her back on the Namenda yesterday she had the same problem again in the morning. Our endocrinoligist thinks it is the Namenda and not the insulin. I have to call her Alzheimer's Doctor today.