A Rare Complication After Pancreas Transplant: What Doctors Learned

Low blood sugar (hypoglycemia) is a common side effect after pancreas-kidney transplantation. Usually, it happens because the new pancreas is working very well, producing insulin when it shouldn't, or because patients need time to adjust their medications. But sometimes, the cause is harder to find.

Doctors often assume low blood sugar after transplant is straightforward to explain. This case shows why they need to keep digging when the usual answers don't fit.

A 60-year-old man with Type 1 diabetes received a simultaneous pancreas-kidney transplant in 2007. For many years, everything went well. His transplanted pancreas worked reliably, and his blood sugar control remained stable.

In 2024—17 years later—he started having severe, repeated episodes of low blood sugar. His fasting blood sugar dropped as low as 40 mg/dL (a dangerously low level), and his HbA1c fell noticeably. Most puzzling: this happened even after doctors stopped his glucose-lowering medications entirely.

When the medical team measured his insulin levels during these episodes, they found something unexpected: his insulin was still high. This suggested his pancreas—or something in it—was producing too much insulin on its own.

Doctors ordered advanced imaging and blood tests. They found elevated levels of chromogranin A, a marker that points to neuroendocrine tumors. Imaging scans revealed a large mass inside the transplanted pancreas, with features consistent with an insulinoma—a rare tumor that produces insulin.

A tissue biopsy confirmed the diagnosis: a well-differentiated neuroendocrine tumor, grade 2, that was expressing insulin. This tumor was the hidden source of the excess insulin causing his severe low blood sugar.

Insulinomas in transplanted organs are extremely rare, which is why they're easy to miss. This case shows the importance of considering uncommon diagnoses when the obvious explanations don't work.

The surgical team removed the entire transplanted pancreas. After surgery, the patient's severe low blood sugar episodes stopped completely.

While losing a working pancreatic graft is significant, it was the right choice to eliminate a life-threatening complication. The case demonstrates how careful diagnosis—using continuous glucose monitoring, blood tests, and multiple imaging techniques—can guide the best treatment decisions.

This rare case teaches doctors to stay thorough when patients have unexpected symptoms after transplant. Low blood sugar, weight gain, or other metabolic changes should be investigated carefully, with consideration of uncommon causes when typical explanations fall short.

For patients with pancreas transplants, the takeaway is reassuring: such complications are exceptionally rare, and when they do occur, modern diagnostic tools can identify them. Working closely with a transplant team and reporting new or worsening symptoms—especially low blood sugar—helps catch problems early.

Source: Frontiers in transplantation. Evidence type: PubMed indexed literature. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.