The embryology behind the condition is elegantly precise. The pancreas forms from two outgrowths of the primitive foregut: a ventral bud and a dorsal bud. The ventral bud gives rise to the head of the pancreas and its uncinate process, whereas the dorsal bud builds the majority of the organ, including the neck, body, and tail, along with the accessory duct of Santorini. When the dorsal bud never appears, the distal pancreas simply does not exist. The clinical consequences can range from complete silence, discovered only incidentally, to abdominal pain, acute or recurrent pancreatitis, exocrine pancreatic insufficiency, and diabetes mellitus. The diabetes is thought to follow directly from the missing tissue: a substantial fraction of the insulin-producing beta cells reside in the body and tail, so their congenital absence reduces endocrine reserve from the very start of life.

In the weeks before his emergency presentation, the young man had been losing weight, roughly four kilograms over eight weeks, and had developed the classic warning signs of rising blood sugar: excessive urination and unquenchable thirst. He had also noticed intermittent discomfort after meals. On the day of admission, the picture crystallized. His blood glucose measured an alarming 412 milligrams per deciliter, his urine tested strongly positive for ketones, and his venous pH of 7.31 with a bicarbonate of 17.2 milliequivalents per liter indicated mild metabolic acidosis, treated clinically as mild diabetic ketoacidosis. At the same time, his serum lipase of 486 units per liter and amylase of 312 units per liter both exceeded their upper reference limits more than threefold, and combined with his epigastric pain and imaging evidence of peripancreatic inflammation, this satisfied the standard diagnostic criteria for acute pancreatitis.

Contrast-enhanced computed tomography delivered the decisive finding. The scan showed complete absence of the pancreatic neck, body, and tail distal to the splenic vein, together with an enlarged pancreatic head measuring 4.1 centimeters in its anteroposterior diameter, minimal peripancreatic fat stranding, and no signs of necrosis, pseudocyst, or fluid collections. A subtle but diagnostically valuable clue, the dependent stomach sign, was also present: with the distal pancreas missing, the stomach settles into the space it would normally occupy. Magnetic resonance cholangiopancreatography, performed eight weeks after discharge, added ductal confirmation by demonstrating a preserved ventral pancreatic duct, the duct of Wirsung, and a completely absent dorsal pancreatic duct, the duct of Santorini. Together, the morphological and ductal evidence established the congenital nature of the defect beyond reasonable doubt.

Reaching that conclusion required excluding a long list of impostors. Pancreatic lipomatosis, in which functioning tissue is replaced by fat, can create the illusion of a missing gland. Chronic pancreatitis can cause distal atrophy and ductal changes, but this patient had no history of chronic inflammation. Prior trauma, necrotizing pancreatitis, or surgery were ruled out by his history. A pancreatic tumor was considered unlikely given his age and the absence of any discrete mass or obstructive lesion on imaging. The etiological workup for pancreatitis also came back clean: triglycerides of 184 milligrams per deciliter and calcium of 9.1 milligrams per deciliter excluded the two major metabolic causes, liver enzymes showed no evidence of biliary obstruction, no gallstones were seen, and the patient denied alcohol, tobacco, drugs, and relevant medications.

The diabetes workup proved equally revealing. Twelve weeks after admission, his fasting C-peptide level was just 0.31 nanograms per milliliter, confirming profoundly low insulin production, while tests for the GAD65, IA-2A, and ZnT8 autoantibodies, the immunological fingerprints of classic type 1 diabetes, were all negative. This combination, severe insulin deficiency without autoimmune markers, in the presence of a major structural pancreatic defect, points toward a structural rather than autoimmune explanation. The authors were careful, however, not to over-classify. Type 3c diabetes, or pancreatogenic diabetes, formally requires evidence of exocrine pancreatic insufficiency in addition to structural disease and absent autoimmunity. In this patient, fecal elastase measured 210 micrograms per gram, within acceptable range, and there was no steatorrhea or malabsorption, so the team preferred the more cautious description of diabetes associated with dorsal pancreatic agenesis and severe insulin deficiency.

Treatment followed established pathways for both conditions simultaneously. The patient received intravenous fluid resuscitation, insulin infusion, analgesia, electrolyte monitoring, and a gradual reintroduction of oral feeding, and his abdominal symptoms resolved without any surgical intervention. Because his admission potassium of 4.3 milliequivalents per liter was normal, no supplementation was needed before starting insulin. He was discharged on a basal-bolus regimen combining once-nightly glargine insulin with pre-meal lispro. Pancreatic enzyme replacement was deliberately withheld given his preserved exocrine function. By week twelve, his fasting glucose ranged from 110 to 140 milligrams per deciliter and postprandial values from 140 to 180, his HbA1c had fallen from 9.73 percent to 7.1 percent, and he had experienced no hypoglycemic episodes, no recurrence of abdominal pain, and no further attacks of pancreatitis.

The case also carries an instructive lesson about the limits of diagnostic imaging. An initial ultrasound described the pancreatic body and tail as normal, but retrospective review showed this reflected inadequate visualization rather than genuine confirmation, a discrepancy fully explained by the well-known difficulty of imaging the distal pancreas through the stomach. The authors were similarly transparent about their own limitations: the only archived CT images were labeled as plain scans, preventing independent verification of the contrast phase, β-hydroxybutyrate levels were never measured, the paired glucose reference for the C-peptide test was not recorded, genetic testing was not performed, and follow-up lasted only twelve weeks. These caveats matter, because they remind readers that even striking case reports rest on imperfect data, and that the enlarged pancreatic head seen during active pancreatitis could reflect inflammatory edema rather than true compensatory hypertrophy.

What makes this report resonate beyond its rarity is the diagnostic challenge it poses to routine thinking. Diabetes in an 18-year-old is usually presumed to be autoimmune type 1 disease, and most of the time that presumption is correct. But this case demonstrates why severe new-onset diabetes deserves a structural look at the pancreas itself. Dorsal pancreatic agenesis has been linked to mutations in developmental genes such as GATA6, a recognized cause of human pancreatic agenesis, and recessive regulatory mutations in PTF1A have been described in isolated pancreatic agenesis, although no molecular mechanism could be attributed in this patient without genetic testing. Compared with previously published cases, including a systematic review of 53 patients and individual reports of DPA with diabetes or ketoacidosis, this patient stands out for the simultaneous occurrence of complete dorsal agenesis, acute pancreatitis, and antibody-negative severe insulin deficiency in one young man. The message for clinicians is clear: when the pancreas is missing half of itself, the diagnosis of diabetes should rest on imaging, C-peptide levels, and antibody studies together, not on age or assumption alone.

Subject of Research: Dorsal pancreatic agenesis presenting with new-onset diabetes and acute pancreatitis

Article Title: Dorsal Pancreatic Agenesis Associated With New‐Onset Diabetes Mellitus and Acute Pancreatitis in an 18‐Year‐Old Man: A Case Report

Article References: Rab, M., Javaid, M. H., Numani, R. N., Khanam, F., Khalid, M., & Segawa, F. (2026). Dorsal Pancreatic Agenesis Associated With New‐Onset Diabetes Mellitus and Acute Pancreatitis in an 18‐Year‐Old Man: A Case Report. Clinical Case Reports, 14(10), Article e73606. https://doi.org/10.1002/ccr3.73606

Image Credits: AI Generated

DOI: 10.1002/ccr3.73606

Keywords: dorsal pancreatic agenesis, pancreatitis, diabetes mellitus, diabetic ketoacidosis, C-peptide, MRCP, congenital anomaly, pancreatic imaging, type 3c diabetes, GATA6, insulin deficiency, case report