Well, as it's a neighbour, I'd probably have a word next time you see her. Explain that untreated low blood sugar can kill T1s such as yourself and unfortunately you weren't able to explain this when she criticised you because your blood sugar was too low for rational thinking. Or maybe write a note.
Dear Ignorant Neighbour (you probably should just put her name here)
I am a T1 diabetic, which means that my body no longer produces any insulin and without multiple daily injections of insulin I would die. Although insulin saves my life, if there is too much in my system (either because of too little food or too much exercise or just because my metabolism is slightly off that day) my blood sugar can go too low, initially causing confusion (my brain is starved of nutrition) and potentially, if untreated, causing coma and even death. This is called hypoglycemia (hypo for short). I wasn't able to explain this to you when I saw you because my cognitive processes were already impaired and I was concentrating on raising my blood sugar before I passed out. And unfortunately I can't just keep my blood sugar high all the time to avoid hypos, because high blood sugar kills too, just much more slowly, via complications such as blindness, renal failure and limb amputation.
I am telling you this because if you ever meet a confused hypo T1 diabetic you may actually be able to save their life by giving them sugar.