I think this may be a matter of trial and error! Potatoes are quite high-carb, and it is apparently high-GI, too; however other root vegetables like carrots, swede, mooli and so on are, I believe, lower in carbs. You can, of course, balance out the GI of your meals by adding legumes of your choice, either whole or blitzing some of them up with some of the stock to act as a thickener. I think I'd make sure to add lots of low-carb veg, too - leek, peppers, courgettes, mushrooms, cauliflower, spinach..... If you measure your blood glucose, as has probably been recommended now you're on insulin, you can see what suits you and what doesn't! We're all different, so what works for one may not work for another!