Since you do have the Libre, I would try to condition her to be ok with the test, it’s the perfect time.
When we first started, Gus was not the happiest about it all. We ended in a small bathroom, I brought all the supplies, sat down with him let him wonder a bit, lots of pets, treats. He’d eventually start to get more comfy and lay down with me. I’d play with his ears, use a rice sock (let him sniff it) to warm his ears… we basically would do everything we would do for a test, minus the poke.. I even had a pen cap to simulate a poke. This didn’t only help him but me too.
Eventually I worked up the courage and tried the poke, he was a little taken by it but shrugged it off pretty quick. Each non poke and poke sessions got easier and easier for both of us.
Also remember that they feel your energy, if you’re nervous they’re like why, if you’re scared they are too. I would actually talk Gus through every step I took, calmly. Some folks will sing a little song - I just figure that would scare Gus more than the poke, so we talked calmly instead