Even low GI foods still cause blood sugar to raise by some amount.
All of the vegetables in the salad have carbohydrates that will raise blood sugar. Carrots, onions, tomatoes, all of that will raise blood sugar. Croutons? Blood sugar.
Obviously selecting a garden salad with no dressing is a healthier choice than "sweet ribs". Most diabetics (that are managing their condition) are not going to be ordering things with refined sugar in them.
Where things get tricky is asking questions like "what's healthier, a honey-miso glazed salmon with brown rice or a salad with croutons and a honey and berry dressing?" or "What's better for you, grilled chicken with a sugary barbeque sauce or fried chicken with no sauce?"