Memory Loss?

Hai, I have been a type 1 diabetic for 7-8 years now.
  Over the past couple of years, but more recently I've begun to suffer memory loss and have to be reminded what I am doing, or what I've done. This is really begun to affect school work as I can not remember what I've learnt. The memory loss is rare as it only happens when my glucose levels drop low very suddenly or if my glucose levels have been high for a substantial amount of time.
Is this normal? What can I do to stop this from happening?

Thanks In Advance for all your help.

Regards
Dennis