Ophthalmology researchers at the University of Louisville have discovered the loss of vision in RP is the result of a disruption in the flow of nourishing glucose to the rods and cones. This disruption leads to the starvation of the photoreceptors.

In research published today in , the researchers, led by Douglas C. Dean, PhD, and Wei Wang, MD, PhD, of the UofL Department of Ophthalmology and Visual Sciences, described metabolic changes that result in the reduced availability of glucose in the cells.

As research provides a better understanding of the progression of RP, this knowledge may lead to therapies that could slow or stop this process before the rods and cones are destroyed. In addition to the relevance for RP, the researchers discovered the failure in glucose metabolism in RP is similar to changes seen in lung cancer and may be useful in developing therapeutic targets for both diseases.

“Interestingly, these metabolic changes appear similar to those we also are investigating in other studies into lung cancer in the laboratory,” Dean said. “Both lung cancer and neurons in the retina use glucose as a primary source for their metabolism. Attacking glucose utilization is a major strategy in fighting lung cancer. This unexpected connection in retinal and lung cancer metabolism has led us to link these seemingly unrelated systems to search for common drugs that target both lung cancer and retinal degeneration.”

RP is an inherited disease in which the photoreceptor cells in the retina – rods and cones – deteriorate over time. Photoreceptors absorb and convert light into electrical signals, which are sent through the optic nerve to the brain. Rods, located in the outer regions of the retina, allow peripheral and low-light vision. Cones, located mostly in the central part of the retina, allow perception of color and visual detail.

In RP, rods deteriorate first, causing the peripheral and low light vision loss typically associated with the disease. In later stages, the cones also deteriorate. Without cone function, RP patients lose the high-resolution daylight vision necessary for reading, facial recognition and driving. As a result, this stage of RP vision loss is more debilitating than the loss of nighttime or peripheral vision. RP affects 1 in 4,000 people globally.

This research is supported by grants from the National Eye Institute, BrightFocus Foundation and Research to Prevent Blindness.

With increasing evidence that an artificial pancreas can improve glucose control in patients with type 1 diabetes, investigators had sought to see if it could also help patients with type 2 diabetes.

The study also found the improved glucose control in patients with type 2 diabetes was achieved without increasing the risk of hypoglycemia. One of the major limiting factors in achieving improved glucose control is the increase in hypoglycemic events.

Conducted by researchers at the University of Cambridge and Manchester University in the United Kingdom, along with the University of Bern in Switzerland, the study was published to coincide with a presentation at the American Diabetes Association’s 78th Scientific Sessions in Orlando, Florida. 

It was notable as most studies of automated closed-loop insulin delivery systems include patients with type 1 diabetes, said Sri Prakash Mokshagundam, MD, an endocrinologist and diabetes specialist with University of Louisville Physicians. It also focused on hospitalized patients, where most studies have focused on outpatients who were already on insulin, he said. About 25 percent of hospitalized individuals have diabetes.

In the study, patients who were not already on a pump or sensor to control their diabetes prior to admission were placed on the system upon admission to the hospital. Mokshagundam said that using the technology in an inpatient setting has certain advantages, such as less burden on nursing staff as they try to manually adjust insulin doses. Meal-time insulin delivery still has to be planned by the health care team.

He said that while the technology helps in the acute setting, procedures need to be developed to transition it from acute to chronic care after patients leave the hospital.

He noted there also are some hurdles at this time to implementing the technology in the United States, as the technology used in the study has not yet been approved by the U.S. Food and Drug Administration for inpatient use here. A slightly different type of system has been approved for outpatient use, which uses a different algorithm to calculate the dose.

“The study that shows that this can be done, but we are still a ways off before this becomes routine practice,” Mokshagundam said. “There is some refinement needed.”