Well as a type 2 I am managing my blood levels with low carb eating, which also helped me lose lots of weight. I am not eligible for shielding support (no letter from the gp) so I minimise my outings around people as much as I can and am rigorous about social distancing and hand hygiene etc. So checking if she has got a letter would be the first step.
The most proactive thing either of you can do is get good diabetic control. Most of us in here do that by eating only a few carbs (Bread, rice, pasta, potatoes, grains of all sort including porridge, flour and cereals etc) and replace them with more fats and proteins. Have a look at the links in my signature below for full details. Come back and ask questions once you’ve read a bit about it.