High blood sugar could worsen effects of spinal injury

Controlling blood sugar in people with spinal cord injuries might aid in recovery and improve their movement and sensory functions. If such trauma patients arrive in emergency rooms with high blood glucose, they fare worse on average than those with normal levels, Japanese researchers find. And in lab tests, mice with spinal cord damage recover faster if their high blood glucose is regulated with insulin within eight hours of the injury, the team reports in the Oct. 1 Science Translational Medicine.

The findings should clear the way for a study in which patients with a spinal cord injury are randomly assigned to standard care or that care plus lowering of blood glucose if needed, says Greet Van den Berghe, a physician and critical care researcher at the University of Leuven, also called KU Leuven, in Belgium. “This is very promising and definitely worthwhile,” she says.

Physician Kazu Kobayakawa of Kyushu University and colleagues examined health records of 206 people with spinal cord trauma who were admitted to a Japanese hospital from 2005 to 2011 and for whom blood glucose information was available. The researchers divided the patients into two groups by glucose level. Roughly half of the patients had 126 milligrams or more of glucose per deciliter of blood, a cutoff point for high blood sugar. The others had lower levels.

The study revealed that, using standard measures of functional impairment, 45 percent of those with high glucose failed to improve with treatment compared with 31 percent of those with normal glucose. Patients with glucose readings above 180 mg/dl were increasingly likely to have fared poorly, the records show.

The analysis included some patients who were paralyzed upon admission to the hospital. Hospitals often treat spinal cord trauma patients who are paralyzed, but who then recover motor or sensory function partially, Van den Berghe says. Part of this improvement is due to a reversal in the swelling of nerve tissue, she says. Such improvement in some cases might be traceable to declining blood glucose. “This inflammation gets resolved quicker and neurons are protected.”

In the new study, laboratory mice that had spinal cord injuries showed worse inflammation if they had high blood glucose. Immune cells in the central nervous system called microglia become activated in a high glucose environment, or hyperglycemia, Kobayakawa says. In the mice, this change triggered an inflammatory chain reaction that caused the death of neurons and other cells. The upshot was slower recovery than was seen in mice with similar injuries but normal blood glucose, the team found.

Blood glucose levels can lurch up and down depending on food consumption. Healthy people have metabolic regulators, led by insulin, that enable cells to use these sugars and maintain blood glucose concentrations in a normal range. “Regardless of whether the patient ate or did not eat,” Kobayakawa says, “we showed that hyperglycemia itself is detrimental for recovery.”

Controlling blood sugar levels with insulin is a fast-acting treatment likely to benefit patients, Kobayakawa says, but only a clinical trial can establish its value.