Welcome to the forums
@chicklet.
That's a high value, 109mmol/mol and an average blood glucose of 16.7mmol/L.
There are folk on this forum who have used diet to achieve remission from this level but it's quite a big ask. Some thoughts
1) Do you have any readings to know if she had issues a year ago?
2) Is she overweight? (Makes T2 more likely and also means low carbing will probably reduce her weight).
3) Has she had covid? (Some reports say it can induce diabetes).
4) How many carbs in a typical day? (This will tell you how much scope you have for reduction.)
Look, low carbing should help and if you buy a glucometer you will get some sort of idea as to whether it's reducing her levels. Don't leave it long before seeing a doctor though, because those levels are dangerous. (Tell them she is going low carb so they don't go overboard on the meds). We are not replacements for doctors on these boards and we can't officially diagnose. (Though if that hba1c is accurate she needs to see a doctor).
My questions may seem a little strange but it's not unknown for someone her age to get slow onset T1 (unlikely if she's overweight) so you should be aware that this is a possibility and if it is so she'll need insulin eventually.
Good luck.