Hi Rob,
According to the Slimfast tin, there are 62g of total carbs per 100g, or 35g carb in one made-up 250ml shake. The sugar content does seem high, bt I don't find them over-sweet.
I'm trying Slimfast for a few weeks to get a good kick start on my next phase of weight loss, though I am an enthusiastic low-carber normally. It will be interesting to see if my BG readings improve with the restricted calories, or get worse with the extra carbs. I shall be posting about that elsewhere.
I've just tested to check, about 1.5hrs after a strawberry shake. I was 5.0 before it, I'm 5.2 after. So they don't appear to spike me.
My low-carb diet is in the Sticky Thread section on the Board Index - Viv's Modified Atkins Diet. It's really Atkins Induction, and it works for me. If you don't want to take your carbs so low, use a carb counter book and add in extra fresh carbs (veg and fruit preferably) until you reach the daily carb level you want. You can eat plenty of food, and you won't feel hungry.
Let us know how you go on, however you diet. We like to pick up tips.
Viv 8)