Pancreas calcifications may help diagnose CF-related diabetes

Pancreas appears normal less often in CT scan of CF-related diabetes

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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A person prepares for an imaging scan as a clinician stands nearby.

More lumps of fat and hardened deposits, called calcifications, may show up on imaging scans of the pancreas of people with cystic fibrosis (CF) who have diabetes, a study shows.

These findings suggest doctors can use computed tomography (CT) imaging to help diagnose CF-related diabetes and distinguish these patients from those without diabetes.

“Physicians should look more closely for diabetes in subjects with pancreas calcifications on abdominal imaging,” the researchers wrote in “CT imaging shows specific pancreatic abnormalities in persons with cystic fibrosis related diabetes,” which was published in Scientific Reports by researchers in France.

The thick, sticky mucus produced in CF can build up in the pancreas and block the release of enzymes needed for breaking down food in the intestines. This can cause digestive symptoms.

Over time it also can damage the pancreas to where it no longer produces enough insulin, a hormone that controls the amount of glucose (sugar) in the blood by moving it into cells, where it’s used for energy.

This can result in CF-related diabetes, “a specific form of diabetes” that occurs in up to half of those with the disease. While feeling thirsty and urinating more often than usual may signal diabetes, people don’t know they have it until a diagnosis, which is based on the results of an oral glucose tolerance test (OGTT). Everybody with CF, ages 10 and older, should take this test every year to check for diabetes.

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Differences in imaging scans of people with CF-related diabetes

Because earlier research spotted CT differences in the pancreas of those with and those without CF-related diabetes, the investigators wanted to know if imaging can be used to tell them apart.

They focused on two features — lumps of fat, or lipomas, “the most common exocrine [gland-related] pancreas abnormality in CF,” and calcifications, which are often “associated with diabetes in chronic pancreatitis [inflammation of the pancreas] from other causes.”

The scans of 41 people with CF-related diabetes and 53 people with CF but no diabetes, who served as controls, were reviewed. Those with CF-related diabetes were a median three years older (33 vs. 30 years).

To account for this difference, the researchers formed two new groups where 32 people with CF-related diabetes were paired by age with 32 controls.

In the subgroups, those with CF-related diabetes were more likely to have exocrine pancreatic insufficiency, which occurs when there aren’t enough enzymes to break down food (100% vs. 63%), and to carry two CF-causing mutations associated with more severe disease (97% vs. 72%).

On CT scans, the pancreas appeared normal less often with CF-related diabetes than with controls (2% vs. 30%).

“Imaging was almost always abnormal in subjects with CFRD [CF-related diabetes], while it was normal in a third of the CF control subjects,” the researchers wrote.

It was also more common for those with CF-related diabetes to have complete lipomatosis, which occurs when lipomas take over the pancreas to where it can no longer be seen on a CT scan (71% vs. 57%).

This difference was in part due to exocrine pancreatic insufficiency and the type of mutations associated with more severe disease, the researchers said.

Indeed, exocrine pancreatic insufficiency was less common with normal imaging findings (29%) than with partial or complete lipomatosis (94% or 95%). Partial lipomatosis is when part of the pancreas is still visible despite lipomas being present.

Nine (22%) people with CF-related diabetes had pancreatic calcifications, whereas none of the controls did, suggesting they “were specific of subjects with CFRD,” wrote the researchers, who called the presence of pancreatic calcifications, seen in almost one in four people with CFRD and not without CFRD, a “distinctive finding.”

One limitation of the study is that when the CT scans were obtained “CFTR modulators were not widely available in France.” This means the study didn’t account for their effect. Still, this remains the first large study to compare the “CT characteristics of the pancreas” with or without CFRD, the researchers wrote.