Preoperative predictors of new-onset diabetes mellitus following distal pancreatectomy for nonfunctioning pancreatic neuroendocrine tumors

Background: Nonfunctioning pancreatic neuroendocrine tumors are typically indolent neoplasms with a rising incidence. Distal pancreatectomy remains the standard treatment for localized tumors in the pancreatic body/tail. Given the favorable long-term prognosis, accurate assessment of postoperative morbidity, particularly postoperative new-onset diabetes mellitus, is critical. Aims of the study were to identify preoperative predictors of postoperative new-onset diabetes mellitus in patients who underwent distal pancreatectomy for nonfunctioning pancreatic neuroendocrine tumors and to develop a predictive model for individualized risk assessment. Methods: Consecutive patients who underwent curative distal pancreatectomy for localized nonfunctioning pancreatic neuroendocrine tumors at San Raffaele Hospital between 2015 and 2022 were included. Exclusion criteria included pre-existing diabetes and follow-up <24 months. Clinical and radiological data were evaluated. Results: After a median follow-up of 58 months, 27 of 65 patients (41%) developed postoperative newonset diabetes mellitus. Postoperative new-onset diabetes mellitus was significantly associated with elevated body mass index (P = .016), pancreatic atrophy (P = .044), increased total (P =.014) and visceral fat area (P = .021), and a higher proportion of pancreatic parenchyma distal to the tumor (P = .046). On Cox regression, higher body mass index (hazard ratio: 1.187; P = .001), elevated hemoglobin A1c (hazard ratio: 1.169; P = .001), and distal higher proportion of pancreatic parenchyma (hazard ratio: 1.030; P = .018) were identified as significant risk factors of postoperative new-onset diabetes mellitus. A nomogram and online risk calculator (https://net-distal-pancreatectomy.shinyapps.io/postoperativediabetes-risk-calculator/) were developed to predict individual risk at 1, 3, and 5 years, with good discriminatory performance (area under the curve: 0.766; P < .001). Conclusion: Postoperative new-onset diabetes mellitus occurred in 41% of patients who underwent distal pancreatectomy for nonfunctioning pancreatic neuroendocrine tumors. Elevated preoperative body mass index, hemoglobin A1c levels, and proportion of distal higher pancreatic parenchyma emerged as significant risk factors of postoperative new-onset diabetes mellitus. The developed nomogram and web-based calculator may support preoperative counseling and guide tailored prehabilitation or parenchyma-sparing strategies in high-risk patients. (c) 2025 Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.