SAN ANTONIO (San Antonio Express-News) — Doctors fear that some parents may be overlooking an important early indicator of diabetes in children — an indelible smudge that appears on the neck or other parts of the body.

Parents have reported scrubbing their kids' necks raw, or even using laundry bleach, with no success. They can't get rid of the grimy-looking, rough-textured patch of skin that sometimes encircles the entire neck.

"This is a warning sign," said Dr. Daniel Hale, a pediatric endocrinologist and associate professor at the University of Texas Health Science Center at San Antonio. "It's like black smoke coming out the tailpipe of your car. Your car may be running fine, but you're eventually going to need to see a mechanic."

The mark is called acanthosis nigricans, Greek and Latin words that describe changes that happen in the skin as the body becomes resistant to insulin.

Insulin resistance is a precursor to type 2 diabetes, a chronic disease in which the body is unable to use insulin properly to metabolize glucose, or blood sugar. High levels of blood sugar result, and that can have devastating long-term consequences — damage to nerves, organs and blood vessels that may eventually lead to blindness, kidney failure or limb amputation.

Type 2 diabetes once was believed to be a disease that occurred mostly in adults over the age of 40. In recent years, doctors have noticed that a growing number of children are developing the adult form of the disease.

Type 2 diabetes is strongly related to obesity and poor diet, and is particularly prevalent in minorities.

Knowledge about a telltale skin marker is significant, doctors say. It offers a window of intervention.

"The big picture is, if you can identify anyone who is at risk and institute lifestyle changes, then you can prevent or delay the onset of a serious, chronic disease," said Dr. Charles Stuart, a professor of internal medicine at the University of Texas Medical Branch in Galveston.

Stuart has studied and written extensively about the skin condition in the last 15 years. While the skin discoloration can occur in adults, Stuart said, it most commonly is observed in children age 10 to 12.

He said it is most useful in identifying insulin resistance in American Indians. As many as one-third of the children Stuart examined in a study had the skin marker. The mark also is very visible in Hispanics and blacks who become insulin resistant, but is less visible in whites.

Most commonly, the discoloration occurs on the back of the neck, but it also has been observed on the skin of the armpits, knuckles, elbows and knees. It is barely recognizable at first, but can progress to become a wide area of coarse textured, dark-looking skin.

Barbara Walz, director of education at the Texas Diabetes Institute in San Antonio, said she sees parents' eyes light up as she talks to groups about the skin marker and what it means.

"I see the reaction in their faces," Walz said. "Mothers will say, "My son has that?' One woman told me she was scrubbing her son's neck with Clorox, because it looks like dirt."

On San Antonio's predominantly Hispanic West Side, Hale said 40 percent of Hispanic middle-school boys and almost 30 percent of the girls are obese, and 60 percent come from families with a history of diabetes. As many as 20 percent of them have acanthosis nigricans.

Similar numbers are being recorded along the Texas-Mexico border, where the state Legislature this year funded the first pilot project to screen school children in nine counties for acanthosis nigricans. The project, being done by the University of Texas-Mexico Border Health Coordination Office, is enlisting school nurses in the effort to examine 150,000 children by the end of the year.

Early indications are that 20 percent of the children have the marker, said Paul Salazar, project coordinator. They will be steered into an education and intervention program aimed at making lifestyle changes — diet, exercise and weight loss. Improvements in diet and lifestyle help make the mark fade, and that often is the best motivator for these young patients, Hale said.

"There's not a girl I've met yet who likes the idea of this dirty black ring around her neck," Hale said. "We can tell them with a great deal of confidence that if they get some weight off, the dark ring will fade, and that is often a stronger motivating factor for them than the fact that they might be able to wear slinky clothes."

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