Jun
You could have given us more details.
I had a problem the first year or so after I was diagnosed. I thought I had some kind of dementia. It actually frightened me. There were times when my mind just didn't work. People would talk to me and I couldn't understand them–I heard the words but I couldn't make sense of them! I had no short term memory, so I'd leave the home, drive two blocks and then think 'Did I lock the door? I don't remember locking the door!' I'd come back and it would be locked, but even as I was walking away, I'd ask myself 'Was the door locked? I don't remember!'
I asked on my e-mail list about this and people stated it might be caused by low blood sugar. I was checking my blood sugar and it wasn't 'low', but much lower than it had been. I had been eating super-low carb. I tried raising my carbs just a bit and I got a lot better.
Anyway that might be your problem. Whatever it is I hope you can figure it out and fix it!
Answer:
How old are you? This started happening to me in my 30's…and to all my friends in their 30's…it's called “getting older”, unfortunately.