Type 3c (Pancreatogenic) Diabetes Mellitus (Type 3cDM) is a form of Diabetes Mellitus resulting from diseases of the pancreas causing pancreatic insufficiency. The most common causes are chronic pancreatitis and pancreatic neoplasms, with infectious etiologies being rare. Pancreatic tuberculosis is an uncommon form of extrapulmonary TB, even in endemic regions such as the Philippines. We report a case of Type 3c DM secondary to pancreatic TB in a patient with HIV infection.

The patient is a 55 year old male, Guamanian, with active Human Immunodeficiency Virus (HIV) infection, poorly controlled with a CD4 count of 6.42 cells/µL, presenting with an 8 month history of progressively enlarging right submandibular mass, unintentional 3-kg weight loss, anorexia, and intermittent fevers. Fine needle aspiration of the neck mass revealed chronic granulomatous lymphadenitis. A whole abdominal ultrasound was also performed for workup of fever showing a hypoechoic mass on the pancreatic head. This was further evalued on endoscopic ultrasound showing nodules on the pancreatic head and body. The specimen tested positive for MTB-PCR, confirming Pancreatic Tuberculosis. On further evaluation, HbA1c was elevated at 7.4%. He had no prior history of diabetes mellitus. Fasting insulin and C peptide were done which were 7.6 uU/mL (NV 5-10 uU/mL) and 2.87 ng/mL (0.78-5.19 ng/mL), respectively. HOMA-IR was computed at 1.6, showing lack of insulin resistance. Capillary blood sugars during the admission were within normal range (88-137 mg/dL) hence no antidiabetic medications were started. The patient was started on anti-tuberculosis therapy and was eventually discharged.

The diagnosis of Type 3c DM was established based on the presence of abnormal pancreatic imaging findings, with an elevated HbA1c of 7.4% in the absence of insulin resistance (HOMA-IR 1.9). The treatment for Type 3C DM includes insulin however this patient had normal capillary blood sugars throughout the admission.

This case highlights a rare presentation of Type 3c DM. In patients with pancreatic disease, a high index of suspicion for Type 3c DM is crucial, as its pathophysiology and management differs significantly from that of Type 1 and Type 2 Diabetes Mellitus.