I'm a diabetic also. A salad would be okay to eat but I would stick with oil and vinegar versus dressing. I eat a slice of cheese before I go to bed. I wake up with lower blood sugars in the morning when I eat something really low carb before bedtime.
Like hawaiianlika I too am a diabetic & would go w/ a salad w/ oil & vinegar; fewer carbs mean a lower blood sugar level when you get up the next day, but to keep it from dropping too low keep glucose tablets with you.