The way I understand it, yes. But I don't think any action would be taken upon something written in a donor card alone. For instance, I have been a blood donor for many years now. I know my blood type (obviously), it's marked very clearly on my card and in my medical record. Still, every single time I give blood it's tested for type first. Which does seem a bit over the top perhaps but I'm sure there's a good reason for that.

Around here, it is possible to request an approved medical alert tag or bracelet to be worn on your person if you have a condition that puts you at particular risk, like diabetes or epilepsy. Not sure how things are in your neck of the woods, but you could always ask your physician.