My more extreme lows were in my first year after dx and I hadn't realized till now that that was probably bc I was using R and NPH then. I feel lucky that homolog became available pretty soon after my dx, bc those other insulins were pretty h*llish.
One was a lot like how you describe, not being able to form words. I was sitting at a table in some kind of study area of the sociology department at my college and one of my profs was there and I think she could see that there was something wrong and came over to me. I can't remember what she said, but I remember just sitting there thinking "spoon" with all my might and not saying it. I had a yogurt in my bag that I was sure I could manage to get for myself if only somebody would give me a spoon! But the spoon problem felt so insurmountable. And then I couldn't even talk. And then I finally got it out, like I just kinda blurted out "SPOON!", loudly. lol And the prof was like, whoa! I actually think she may have already known I was diabetic... but anyhow, that's all I really remember about it. I think she got me a spoon and I ate my yogurt and that was that.
During that same time period, I had one where I was walking down the street and FELL. How embarrassing. I think that was actually in the first month or so after dx. And there were one or two times where I felt like I couldn't control my limbs. Like I'd try to move my arms and they would move but not right, like they'd just flail around. My husband (then boyfriend) was there for that and it scared the crap outta both of us. That might have been the only low that I feel like I really needed someone else's help (I woulda drunk that yogurt eventually, I think, if there was nobody to get me a spoon, lol).
The worst, though... drumroll please... was more recent, happened maybe a half dozen times in the last 6 or 8 years, but maybe has stopped since I started using my omnipod, were horrid horrid nightmares that I couldn't wake up from in which I was responsible for saving the world and couldn't or didn't. These dreams felt like they went on forever, like hours, though, for all I know it was ten minutes. But when I would wake up from them I would be so disoriented that I was really not sure if the dreams might be real and the world was ending or over. And I'd have this realization that I had to kill myself FAST to escape some awful fate. And a couple of these lows occurred when my younger son was an infant and in bed next to me and I just laid there unable to move with tears running down my face feeling so confused and scared about what I'd have to do. When this would happen, it always seemed like I'd lay there being completely freaked for quite a while, and then BOOM I would realize it was a low and then everything was normal again and I'd just get up and get some skittles. I spent a lot of time talking about this in therapy. It was AWFUL! And it really made me feel like I understood what it was like to be seriously mentally ill and completely not in touch with reality.
ETA: Just remembered one more, though not much detail about it. It was in the last five years or so and I was at home and dh was out, not sure if kids were here, maybe asleep -- and I was kinda wandering around our 900 sq foot house and I was LOST, like I couldn't figure out how to get to where I was going. Good grief!