While eating immediately before the shot isn't as critical, she just needs food prior to when the insulin starts taking effect, generally somewhere around 4-6 hours after the shot. However, again, with as slim of data as you have, no shot if it were me.
Take this time to grab a few extra tests though if you can, because data on what happens when she doesn't get a shot at that level is just as important as if you gave her a shot. Try for what would be a typical +4/5/before bed and closer to +9/10. If you can grab a test about 1 hour after she eats, that would be good info just to see how far up eating drives her numbers.