Endocrine Abstracts

Introduction: Type 3c diabetes (pancreatogenic diabetes) affects 20% of individuals following partial pancreatectomy and 86% of individuals following total pancreatectomy. No guidelines advise on routine C-peptide measurement post pancreatectomy to help diabetes management. We present two cases of post-total pancreatectomy where C-peptide measurement significantly altered management.

Case Report: Case A was an 80-year-old woman treated for intraductal papillary mucinous neoplasm (IPMN) with total-pancreatectomy. Post-operatively, the patient developed hyperglycaemia and was started on a basal-bolus insulin regimen. Two months post-operatively, she was seen in the diabetes clinic where CGM showed low glucose variability (CV 24.1%) and a good time in range (42%). Random C-peptide was elevated at 276 pmol/l, suggesting residual pancreatic function. Diabetes management was simplified to basal insulin with gliclazide. Case B was a 65-year-old man who underwent Folfirinox chemotherapy followed by a total pancreatectomy for adenocarcinoma of the pancreas. Post-operatively, the patient had hyperglycaemia and was started on a basal-bolus regimen. Two months later, he was seen in a diabetes clinic where CGM similarly showed low glucose variability (CV 20.7%) and excellent time in range (81%). Random C-peptide was significantly elevated at 1,050 pmol/l, and he has successfully weaned off all diabetes medications (TIR 83% off medication). CT abdomen pelvis showed a fluid-filled structure (6.7 x 7.7 cm) at the site of the pancreatic tail bed which may represent post-surgical collection with debris or tumour recurrence.

Discussion: These cases highlight the potential significance of post-operative C-peptide testing in patients undergoing pancreatectomy. Both patients exhibited substantial endogenous insulin production, leading to simplified or discontinued insulin therapy. Routine C-peptide measurement may help to guide clinical management of type 3c diabetes post-pancreatectomy and prevent unnecessary insulin prescriptions