I know exactly what you are talking about. My stats are not too far off yours. I'm 44 now - diagnosed type 1 in 1997. I've had many hypos in the last 18 years. I had my first appointment with a memory specialist (and another doctor and another consultant) yesterday. The memory specialist did a whole bunch of tests with me - both for memory and cognitive function. I was told that (almost undoubtedly) that my memory issues and noticeably slow cognitive function has been caused by the recurrent hypos. I have particular problems with short-term memory and struggle to rapidly process information provided to me and provide an immediate response. I'm scheduled for a brain scan to see if the damage is visible.
Feeling quite down about it to be honest. Gotta stop those hypos.