Hello from another grandma! You are absolutely right in your question. Low blood sugar affects one's thinking processes. My husband is diabetic but not as severely; I have several friends, however, whose diabetic family members need that sort of extra help.
Once my husband and I were at a college reunion with two dear friends (who are married to each other). The husband is diabetic (he's on a drug pump now), and in the course of one morning we had separated, as couples, to do various things. My husband and I were at a snack bar when she marched in, practically dragging her husband behind her, snatched a bottle of Coke out of the cooler, paid for it, shoved it at him, and ordered him, "DRINK THIS RIGHT NOW!" Well, she does teach middle school, but we were surprised at her talking to her husband like that. An hour later, though, when he was better, he explained that when his sugar really drops, his brain really drops, too. She was doing the kindest thing right then. Kind? She might have been saving his life.
I have another friend whose husband's sugar goes crazy minute by minute, and she does have to supervise minute by minute as well. She's done it for years. She knows it's not childishness, it's blood sugar! One of their sons has the same freaky diabetes, and she was so glad that he married a gal who knew how to handle it (and him, when necessary).
It's one of those things that comes under "for better or for worse, in sickness and in health," whether you made that specific promise at your wedding or not. I hope your husband is being checked regularly by your doctor. You would be wise to talk with the doctor as well, and ask him/her these good questions you have. You're certainly on the right track.