Thanks for posting your query.
There may be possibilities of age induced weakness in smooth muscles of gastrointestinal tract.
Nauseated feeling may be due to decreased gastrointestinal motility and may be a part of gastrointestinal complications of diabetes
You should consult with internal medicine specialist and should go for thorough check up.
If possible, then she should also go for endoscopy
She should take frequent small meals.
She should take low fat soft diet
She should take prokinetics for increasing gastrointestinal motility.
Dr. Mayank Bhargava