Introduction:Enteral tube feeding is an effective method of providing nutrients for patients who are unable to meet their nutritional requirements, and patients with parenteral nutrition are at an increased risk of infection. The submandibular gland is one of the major salivary glands and sialadenitis are often caused by obstruction of the salivary outflow tract.Patient concerns:A 91-year-old woman had parenteral nutrition with nasogastric tube feeding. Her history includes angina pectoris, myocardial infarction, type 2 diabetes mellitus (T2DM), heart failure, atrial fibrillation, sick sinus syndrome, and she recently had a pacemaker implanted. She was continued parenteral nutrition with nasogastric tube feeding for 20 days, and her fasting blood glucose ranged from 200 to 400 mg/dL. In the midst of poor glycemic control, she suddenly had high fever and elevated infection markers under poorly glycemic control.Diagnoses:She had neck swelling with a feeling of heat. We performed cervical computed tomography, and it revealed swelling of the bilateral submandibular glands and fluffing of surrounding tissue. She was diagnosed with acute submandibular glanditis.Interventions:We treated her with antibiotics therapy, extubation, daily massage of the submandibular gland and strict glycemic control.Outcomes:Her neck swelling disappeared about 11 days after such treatment.Lessons:We reported acute submandibular glanditis induced by nasogastric tube feeding under poorly controlled diabetes mellitus. We have to keep good oral hygiene and also pay attention to glycemic control in subjects under parenteral nutrition with tube feeding management.