I have spent time in hospital and have encountered no choice but high carbs on the wards. Being intolerant to carbs is similar to an allergy, the treatment is avoidance.
After a week of having a fasting test, they offered weetabix or toast! This happened despite my efforts of educating the sister and nurses who were looking after me.
I had to do it all over again with my eOGTTs, the first, I had a bad hypo and they gave me lucozade and a sandwich, despite being intolerant to dairy. Which they knew about.
Only a few weeks ago, I was taken into hospital over Easter weekend and due to tests, it was too late to get low carb, and the nurses did try, the hospital shop was closed because of covid. In the end the sister on the ward ordered a salad for me, which was crisp and fresh along with gratitude from me, and no they didn't charge me.
I have stayed on a diabetic ward and some of the choices the food is unbelievably high carb such as creamed mashed potato and concentrate
orange juice, if you are vegan, the limitations are worse.
I have had discussions with my endocrinologist about the whole dietary issues of a stay in hospital with those who have an intolerance to carbs.
As others have previously said, order in or get someone to drop at reception, you will get it.
Keep safe