I did some research when I first decided to investigate using non-sugar sweeteners.
Be aware that most sugar alcohols - sweeteners with names ending in "itol" are actually very high in carbohydrates, but these are not processed like normal carbs - i.e. not absorbed into our blood stream - so have no actual effects on our glucose levels. However they have a big downside in that many of them (but not erythritol fortunately) can have some very nasty gastric side effects, such as bloating, wind, and diarrhea, particularly if used in larger quantities.
I found two sweeteners that are generally recommended for diabetic use are stevia and erythritol. Neither affect your glucose levels, contain no or very few calories, and are said not to have any unpleasant side effects. However, some stevia can have an unpleasant to some aftertaste, but there are a couple of different types and stevia "Reb A" is the one that shouldn't do this!
Stevia in itself is extremely sweet (aprox 200 times as aweet as sugar!), ad is generally mixed with other ingedients and/or fillers because of this, and it can sometimes be mixed with "real" sugar, other sweeteners, or starchy fillers to enable it to be used in measurable quantities, but these additives may affect glucose levels, so always check ingredients! Try to look for stevia/erythritol combinations.
Xyitol is also supposed to be OK and particularly good for baking use, but as it can be lethal to dogs in very small quantities, I personally won't have anything to do with it.
Robbity