Diabetic dog usually will have their special dog food recommended by the veterinarian. When you are considering to give them treats, such as after their insulin injection as a reward, please ensure that the treats are safe for them. Avoid treats that are high in carbohydrates or sugar, including all semi-moist commercial foods and treats that use propylene glycol or similar ingredients. Look for foods that contain moderate dietary fiber and low-glycemic index. Do some research and consult with your vet before feeding any treats to your diabetic dogs.
Generally, treats should be given in moderation and in small portion. According to some diabetes information I found on the internet, both for dogs and human, vegetables and fruits are the safe treat. However, you'll need to beware of high sugar content in some fruits and vegetables. Remember, proper diet is essential to diabetes management. In small portion, vegetables like carrots and broccoli are good choices. Steam them first for better digestion. Other vegetables and fruits to consider are lettuce, cucumbers, green beans, strawberries, pears, and apples (remove seeds and core). You may freeze them first for added crunch appeal.
With a consistent in proper care and nutrition, diabetic dogs can have a happy, active, and long life as other dogs.