THU362 A Diagnostic Dilemma: Type 1 Diabetes Vs. Pancreatic Diabetes
Authors: Rafat Ummara , Alshantti Raeda , Kim Matthew , Gilden Janice L 
Published: October 2023

Disclosure: U. Rafat: None. R. Alshantti: None. M. Kim: None. J.L. Gilden: None.

Background: Several presentations of diabetes mellitus (DM) do not fit the classic descriptions. Type 1 DM, characterized by immune-mediated destruction of insulin-secreting cells of the pancreas, typically appears before age 40. The first antibodies described associated with development of Type 1 DM were islet cell autoantibodies, and later antibodies to insulin, glutamic acid decarboxylase, protein tyrosine phosphatase, and Zinc transporter 8. Pancreatic DM or type 3c, is characterized by functional deficiency of the pancreas to secrete insulin and maintain glucose homeostasis. It may be caused by acute or chronic pancreatitis, trauma, neoplasia, hemochromatosis, fibrocalculous pancreatopathy, genetics, or idiopathic, and is commonly misdiagnosed as type 2 DM. Case Presentation: We present a 73-year-old Caucasian male with Type 1 DM and retinopathy, neuropathy, hypertension, hyperlipidemia, benign prostatic hyperplasia, obstructive sleep apnea. He was diagnosed with Type 1 DM at age 33 with BMI=29 and hospitalization for diabetic ketoacidosis, and symptoms of polyuria, weight loss, and visual disturbances. He was started with insulin injections. Antibodies were not measured, as they were not widely available at that time. Family history: MI in father and brother and type 2 DM in grandfather. He later started using insulin pump at age 58 for wide fluctuations in blood glucose levels. At age 64, he presented to our endocrine clinic for continued management of assumed autoimmune Type 1 DM. Physical examination: BMI 36, abdominal lipodystrophy, abnormal monofilament with decreased sensations in the left foot. Laboratory: HbA1c=6.7%. c-peptide was low (0.09 ng/mL; normal range: 0.81 - 3.85) with a concomitant BG of 243 mg/dL suggestive of low insulin reserves. After several years, with the development of increased trust, the patient felt confident to reveal a hidden history of extensive alcohol abuse in his 20s, resulting in recurrent episodes of symptoms suggestive of pancreatitis, which required extensive rehabilitation for his drinking problem. He admitted that he had not divulged this history previously. This additional history proved critical to acquiring a correct diagnosis. With this in mind, we deduced that it is highly probable this patient's recurrent bouts of subacute pancreatitis due to alcohol consumption resulted in development of pancreatic DM. Conclusion: Our patient initially presented with the diagnosis of autoimmune type 1 DM. However, after many visits, he first admitted to a past history of long-standing alcohol abuse, which now suggests that he actually has pancreatic DM. Correctly classifying DM can prove crucial to formulating an individualized treatment plan. It is important to note that the classification of DM is not always clear-cut and involves a periodic review of the medical history and clinical characteristics, besides review of laboratory data.

Presentation: Thursday, June 15, 2023