Suspected Noninsulinoma Pancreatogenous Hypoglycemia Syndrome Following Truncal Vagotomy and Pyloroplasty: A Case Report

Low blood sugar is a condition where the body's fuel supply drops too low to keep the brain and muscles working properly. For most people, this happens when they skip a meal or take too much medication for diabetes. However, in rare cases, the body produces too much of its own insulin, the hormone that tells cells to absorb sugar, causing levels to crash even when a person has just eaten. This internal overproduction can stem from a tumor, but sometimes it arises from a subtle, widespread change in the pancreas itself, a condition known as noninsulinoma pancreatogenous hypoglycemia syndrome. While doctors often look for a single, distinct growth to explain these symptoms, this syndrome involves a diffuse thickening of the insulin-producing cells that imaging scans often miss. Understanding this distinction is vital because the treatment for a tumor usually involves surgery, whereas this syndrome often responds to changes in diet and medication.

A team of researchers from Rwanda and Ethiopia recently documented a striking example of this rare condition in a man who had undergone stomach surgery nearly two decades earlier. The patient, a 46-year-old man, had originally received a procedure called truncal vagotomy and pyloroplasty to treat a severe peptic ulcer that had blocked the exit of his stomach. This surgery, which involves cutting the nerve supply to the stomach and widening the opening to the intestine, was a standard treatment for such blockages in the past. About one year after the operation, the man began experiencing episodes of trembling, rapid heartbeat, and confusion roughly three to four hours after eating meals rich in carbohydrates. These symptoms grew worse over six years, eventually forcing him to seek medical help. When he checked his blood sugar during these attacks, the levels were dangerously low, ranging between 47 and 53 milligrams per deciliter.

To find the cause, the medical team conducted a series of tests while the man was experiencing an episode. They found that his body was producing high levels of insulin, along with elevated amounts of C-peptide and proinsulin, which are markers that prove the insulin was coming from his own pancreas and not from an external source. Crucially, his body was not breaking down fat for energy, a sign that the low sugar was driven by excess insulin rather than starvation. The team also ruled out other common causes, such as the presence of antibodies against insulin or the use of hidden diabetes medications. When they scanned his abdomen with magnetic resonance imaging, a powerful technique that creates detailed pictures of internal organs, they found no tumor or mass in his pancreas. The absence of a visible growth made a diagnosis of insulinoma, the most common cause of endogenous hyperinsulinemic hypoglycemia, highly unlikely.

Given the timing of his symptoms, which occurred only after eating, and the negative imaging results, the doctors suspected noninsulinoma pancreatogenous hypoglycemia syndrome. This condition is thought to occur when the rapid emptying of food from the stomach, a side effect of his earlier surgery, triggers an exaggerated release of hormones that stimulate the pancreas to dump too much insulin. Without the ability to perform more invasive tests that were unavailable in their setting, the team relied on this clinical picture to make their diagnosis. They treated the patient by changing his eating habits, advising him to eat smaller, more frequent meals with complex carbohydrates and protein, and by giving him a medication called acarbose. This drug works by slowing down the absorption of sugar from the intestine.

The results were immediate and significant. Within a month of starting this conservative management plan, the man's episodes of low blood sugar decreased markedly in both frequency and severity. He no longer suffered from the disabling confusion and weakness that had plagued him for years, and his quality of life improved. This case report highlights that even decades after stomach surgery, patients can develop complex metabolic issues that mimic more common conditions. It serves as a reminder that when a patient presents with low blood sugar after eating, and scans show no tumor, doctors should consider this rare syndrome. Recognizing it allows for effective treatment without the need for unnecessary and risky surgeries, offering a path to recovery through careful management of diet and medication.