Thanks @jennifer1967 my husband also has type 2 diabetes but doesn't take Metformin or any other tablets for it. He doesn't sleep during the day but I have noticed he yawns a lot - I put it down to the fact that he wanders around at night, has showers and shaves at ridiculous times of the night and early morning and leaves lights on all around the house. As a result I don't get a full night's sleep either. I will get him to take the Memantine in the evening and see if it makes a difference.mine on 20mg after doing 5mg each week. hes had it 2 years now and no problems. he does have metformin for type 2 diabetes twice a day.