I would love to be able to help you with this, but the vagaries in and management of blood sugar and insulin dos aging, minute-to-minute and day-by-day, requires such an intimate knowledge of circumstance, diet, medication influences, the presence (or absence) of intercurrent illness or infection, and sometimes the downright 'orneriness' of the diabetic state itself, that any advice from the other side of the world via a faceless Internet 'advisor' would be (1) most unwise .. both from your and my perspectives (2) would like-as-not be incorrect and (3) be far less valuable or reliable than the advice and explanations you will get from your treating team. I can only suggest you seek their input again ... though it must be said that - sometimes - in the behavioural see-saw that can be the blood sugar, there may be no certain explanation for the sudden up/down rollercoaster that blood sugars can ride.
I know you worry a lot about your mum, and she is lucky indeed to have such a caring and attentive son .. but bumps and twists and turns abound for most dialysis patients, and one of the hardest things to manage, as a carer, is to take those and deal with each of those obstacles as they come, and not be thrown by them.
You will need the added support of your treating team to help you through this - perhaps to help you as much as they are a help to your mum - so seek their comfort and care.
Again, the Internet is a wonderful (but limited) beast ... but, having acted as an Internet resource for the Home Dialysis Central team for many years - in particular to explain the dialysis process rather than specific day-by-day medical problem - I have held fast, from the very start, that for the latter, face to face contact with home teams always wins out.