Hi Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concern... Halitosis can occur in patient with diabetes due to production of ketone bodies, but this occur due to severe deficiency of insulin & is very rare. Common causes of halitosis are Poor oral hygiene, dry mouth , gingival or periodontal problems , decayed tooth, or it can be related to some illness like salivary gland disorders, sinus infection, bronchitis , pneumonia, or acid reflux in GERD. Drymouth, periodontal disease(gum problem) are extremely common in diabetic patients. You can do is maintain proper oral hygiene , properly brush your teeth twice daily, do chlorhexidine mouthwash twice daily, Do luke warm saline gargle two - three times a day, clean your tongue properly using tongue cleaner. Consult a dentist and go for oral evaluation for gums condition at first. Hope this information helps