Protein may predict diabetic complications.

Protein may predict diabetic complications

Insulin-dependent (Type I) diabetics who suffer from disease-related blood vessel damage often have elevated levels of a blood protein called prorenin. Now, a study suggests that a diabetic's prorenin levels may increase significantly 18 months before any vessel damage shows up in the eyes or kidneys.

If further research verifies that finding, the protein may someday serve as an early warning of microvascular complications, giving physicians "a better chance of helping people avoid [diabetic retinopathy and kidney damage]," says Darrell M. Wilson of the Stanford University School of Medicine.

Over periods averaging about two years, Wilson and John A. Luetscher of STandford took blood samples from 135 children and adolescents with Type I diabetes, who also underwent periodic physical examinations.

During the study, nine of the diabetics developed kidney damange (indicated by increased amounts of albumin in urine) and/or diabetic retinopathy, a vision-robbing disorder caused by leaky blood vessesl in the eye. Eight of the nine had at least one blodd sample showing higher-than-normal prorenin concentrations an average of 18 months before the onset of symptoms, the scientists report in the Oct. 18 NEW ENGLAND JOURNAL OF MEDICINE. Among the diabetics who had consisitently normal prorenin concentrations, only one developed microvascular complications during the study, the investigators say.

Prorenin is a precursor of renin, a kidney enzyme that helps regulate blood pressure. Its role as a possible marker and perhaps even as a contributing cause of diabetic retinopathy and kidney damage remains unclear, Wilson says. But he suggests that prorenin overproduction may offer one of several indicators that vessel damage has begun or will soon start.

If the new findings are confirmed, he adds, physicians may wnat to intensity efforst to prevent or delay diabetic blood vessel damage whe prorenin levels first rise.

Wilson notes that most insulin-dependent patients donht to develop such complications until five year after the onset of diabetes. The National Institute of Diabetes and Digestive and Kidney Diseases estimates that 30 percent of all diabetics develop complications after 10 years with the disease, and 40 percent after 25 years.

Tight control of blood sugar may offer one strategy for staving off microvascular complications, but such control has proved difficult to achieve. In another approach, several researchers have begun testing a variety of drugs that might delay or prevent diabetic complications, notes Ronald D. Brown of the University of Oklahoma Medical School in Oklahoma City. Among these agents are aminoguanidine -- which may prevent damaging reactions between glucose and certain proteins -- and several antihypertensive drugs, including some that block an enzyme that acts on a byproduct of renin.