Hello, as per your query, your dentist is right regarding
diabetes. But you can go for scaling / oral prophylaxis even in case of uncontrolled diabetes. Diabetes and periodontitis has two way relationship. So by removing the local irritants we can reduce the periodontal inflammation and can enhance the diabetes level. But consultation of diabetologist is mandatory. Other point in your query, if the oral health is neglected then tooth loss is obvious.
Next Steps
do visit a periodontist and general physician for proper evaluation and management