(Almost) ditto on that Les. Diet controlled, I've been told to stay away from them and just concentrate on healthy eating.
While they can have a place as you go through the process of learning what are "good" and "bad" things to be eating...not always common sense because there's an element of how quick the sugars are released rather than just sugar content itself...the position at my surgery was that it's an unnecessary expense with little benefit. When I was using one I was regularly getting what I thought of as worrying readings while my HbA1C reading was sat at 6, so fine.
Where the "(almost)" comes in is around Type 1 vs 2 diabetes. My wife was Type 2, insulin controlled. She did have a meter and was supposed to use it on an ongoing basis as she could vary her insulin dose. So there are cases...and I'd imagine someone who was tablet controlled but not very well controlled is another...where Type 2 diabetics need to use them.