Most non-starchy vegetables are very low in carbohydrate -- less than 5 grams for half a cup worth. But there are differences between them. See this master vegetable list for complete information, but here is a quick rule, dividing vegetables into four groups, depending on what part of the plant they come from. There are exceptions, but as a general rule, this works pretty well.
- Leaves have the least amount of carbohydrate, and what little there is is wrapped in so much fiber that there is little, if any, impact on blood sugar (this could be helped by the fact that they all contain enormous amounts of vitamin K). They are also rich in phytonutrients, vitamins, and minerals. Examples: lettuce, spinach, Swiss chard, herbs. Also, alfalfa and other fresh sprouts (but once you grind up sprouts and pack them together, as in some types of bread, all bets are off, blood-sugar wise).