Islet cell infusions make further gains in diabetes

Treating type 1 diabetes with pancreatic islet cell transplants has made progress; studies from both sides of the Atlantic show positive long-term results. Findings presented at the 2004 RSNA meeting added weight to existing data while hailing ultrasound's increasing role in guiding infusions and evaluating patients before and after intervention.

Most patients with type 1 diabetes can keep their condition under control by following a therapeutic regimen. But patients with labile type 1 diabetes face abrupt glycemic swings that can lead to seizures, unconsciousness, and even acute diabetic coma without warning.

Until recently, transplantation of pancreas and kidneys, together or separately, offered the best treatment. The infusion of insulin-producing islet cells, however, might change that.

Dr. Massimo Venturini and radiology colleagues at Vita-Salute San Raffaele University in Milan, Italy, found that more than half of 34 uremic diabetic patients had well-functioning islet cells six years after percutaneous intrahepatic transplantation. The patients underwent a total of 58 technically successful procedures, 51 of which required only a single puncture. They achieved a mean insulin independence rate of 21 months. Islet cell function decreased linearly with time, ranging from 77% at one month to 39% at 84 months.

Using ultrasound, the researchers detected focal steatosis in 12 patients six months after islet cell transplantation. This buildup of fat in the liver cells was probably a byproduct of high insulin concentration from hyperfunctioning islet cells. Complications consisted of bleeding and thrombosis in three patients, all treated successfully.

In the past, islet cell transplants via portal vein catheterization were done mainly with fluoroscopic guidance. Now, ultrasound plays an important role in the various phases of the procedure, including pretransplant evaluation, intervention, guidance, early diagnosis of complications, and postprocedural assessment. It helps guide the portal vein puncture and needle advancement into the liver, limits the number of puncture attempts, and shortens the procedure time, Venturini said.

Surgical kidney-pancreas transplantation still represents the best therapeutic option for simultaneously curing diabetes and chronic renal insufficiency in type 1 diabetic uremic patients. Islet transplantation, however, can make up for the loss of pancreatic endocrine function in cases of pancreas damage at harvesting. It prevents complications of type 1 diabetes such as nephropathy and retinopathy and preserves liver function without major side effects, he said.

Although the islet cell function rate in the Italian study is somewhat low, it provides much better results than those published five years ago, matching the success rate and complications of other published trials, said Dr. Richard Owen, an interventional radiologist at the University of Alberta Hospital in Edmonton. Owen was principal investigator for the Edmonton Trial, which provided the interventional protocol that Venturini and his group observed.

While the guidance method is not crucial, ultrasound can render this procedure safer and faster and can potentially expand the number of centers that could perform it, Owen said.