Hi.. Thanks for the query.. I have gone through your query and can understand your concerns... As per your complain a swollen lump under the jaw can be a swollen lymph node which can be due to infection in the head and neck region or teeth on the left side.. As you have high blood sugar, such patients are more prone to develop infections and infection can lead to swelling in the lymph node and there can be pain when the swollen lymph node is palpated.. Other cause of swelling under the jaw can be an infection in the submandibular salivary gland or blocked duct of the gland by some foreign body or crystalline stones formed in the duct of the gland or the gland itself.. You should immediately consult an oral physician and get evaluated and the physician can also advise you to get an x-ray done or a biopsy to confirm the diagnosis.. Once the diagnosis is confirmed treatment can be initiated.. Antibiotics can be advised in case of infections while surgical removal of the stones can be done in case of gland or duct stones.. Hope this information helps.. Thanks and regards..