I struggled for a long time with mine until I learned to listen to my body more than the doctor. Eventually he stopped bugging me and said to do what works BECAUSE my numbers finally came down eating my way. Carbs have always given me grief unless I pair them with protein. Typically I have a 4-egg omlette (usually with cheese) and a homemade corn muffin for breakfast, a HUGE salad with everything but the kitchen sink in it for lunch , and meat, a couple of veggies, a fruit, and maybe half a potato or small pasta for supper. My desserts are sugarfree Jello or pudding, or an apple, peach, or pear off the tree. I stay away from the grapes, though.
I can without sugar or salt, and I allow myself to eat free choice of veggies--cooked, canned, or raw--whenever I feel like having a snack. I have a weak spot for ice cream, so I bought myself some tiny custard cups and that is the size of the serving I allow myself. I do the same when I get a yen for mashed potatoes. My salads tend to be a little bit of everything--several kinds of lettuce, tomatoes, peppers, celery, carrots, onions, cucumbers, broccoli, cauliflower, snap beans, diced meat, grated cheese, hard-boiled egg, and my own homemade vinegar/olive oil/spices dressing (I make my salad in the largest mixing bowl I have [about 6 cups all told] and munch for about an hour). My all-time favorite salad is diced tomatoes with onions and my dressing, which I allow to "steep" for a few hours before eating--very tangy!
I learned the hard way that the so-called sugarfree cookies, candy, and the like just shot my readings through the roof.
It really takes experimenting to see what works for your particular body. I've learned that--for me anyhow--bread is a no-no on a regular basis, altho I can get away with a pizza once in awhile if I don't make a hog of myself with it and only eat 1-2 slices--but it certainly isn't anything I can do on a weekly basis and keep good readings. For me the carbs have to come as fruits and veggies and NOT as flour-based items.
HTH
Rusty
edited to add that the Mayo Clinic site has the exchange lists I used to get started.