Hi Tesseleanor,
I think the answer to your question is that it really doesn't matter which artificial sweetener you use because none of them will have any effect on blood sugar. It's really down to which one has the taste you prefer. I think what your friend was referring to is the sugar substitutes that are sometimes used in sweets, chocolate, cakes, yoghurt, etc. These are made from sugar alcohol (a form of laxative) - if you look at the ingredients the name always ends in "ol" (like sorbitol, maltitol), and they do raise your blood sugar although not as much as sugar itself.
For a diabetic sugar is not the main problem. By all means cut out sugar if you can but what causes the greatest raise in blood sugar is carbohydrate, and the worst culprits are the starchy carbs, bread, cereals, cakes, rice, pasta and potatoes. These are simply fillers and contain very little vitamins or minerals. If you can change your diet so that most of your carbohydrates come from vegetables and fruit then you are also getting a healthy amount of vitamins, minerals and fibre, as well as keeping your blood sugar at a lower level.