There was a programme on the TV some time ago. Can't think of what it was called but was a doctor who, each week, presented some research he undertook, but on small scale. One of them was to have half of a group of non-diabetics, ie 4 people who continued to eat as they normally would, and the other half, again non-diabetics, who also normally took sugar, to take sweeteners. This to be done for a period of time. The result were that the first group (continue as they would normally) showed no change in blood results re glucose levels / ? HbA1c (can't remember) but the second group, ie those taking sweeteners, had increased glucose levels from their levels before the research.
On that basis, I decided to cut all sweeteners and all diet drinks, unless that was my best choice at the time. I'm not one for fizzy drinks anyway so it hasnt been too onerous but, a year on and I still don't enjoy my cup of tea without some means of tasting sweeter!!! One day, I'll perhaps enjoy a cuppa the same as 'before'