Compound reverses diabetes damage.

Over their lifetimes, about 60 percent of people with diabetes suffer nerve damage, which typically results in numbness or tingling in the feet or hands. Less commonly, similar nerve damage may undermine the body's control of blood pressure, cause incontinence or impotence, or trigger bouts of diarrhea or constipation.

A new study in diabetic rats suggests that this second type of diabetes-induced nerve damage can be reversed with doses of an insulinlike growth factor called IGF-I.

In both people and rats with diabetes, the branching extensions of nerve cells swell up, blocking normal communication between cells, says Robert E. Schmidt of Washington University School of Medicine in St. Louis. Giving diabetic rats daily injections of IGF-I for 8 weeks almost completely reversed this process, he and his colleagues report in the November AMERICAN JOURNAL OF PATHOLOGY.

Compared with 11 untreated counterparts, 8 rats treated with IGF-I had only 14 percent as many swollen nerve endings among nerve cells in the abdomen. In fact, the team reports, nerve dysfunction was no more apparent in the treated rats than in seven rats without diabetes.

It isn't clear exactly how IGF-I works, Schmidt says. Earlier research established that humans and rats with diabetes have lower than normal concentrations of IGF-I in their blood. He speculates that diabetes prevents nerve cells from developing properly and that IGF-I plays a role in restoring normal growth. The compound doesn't stop diabetes, since the IGF-I injections didn't help animals control their blood sugar concentrations.

"Although precise control of blood sugar levels would eliminate the development of nerve damage in diabetics, this is often difficult to achieve," Schmidt says. "The hope is that these findings might help prevent diabetic nerve complications even in people who can't control their diabetes well."