In recent years, obesity has steadily increased—and with it, so has the number of children and teens being diagnosed with type 2 diabetes. What was once considered an adult condition is now showing up earlier than ever before.

Fourteen-year-old Pantera experienced this firsthand when she began noticing strange changes in her health.

She felt thirsty constantly. She started having frequent headaches and unpredictable mood swings. And most noticeably, a dark band appeared around her neck.

This ring wasn’t just a random skin issue. According to Dr. Alyne Ricker, a pediatric endocrinologist at the Joslin Diabetes Center in Boston, this type of darkening—called acanthosis nigricans—can be an early warning sign of insulin resistance. “When your body starts pumping out too much insulin—which is common with type 2—receptors in the skin folds respond by making extra pigment,” Dr. Ricker explains.

These patches of dark skin can show up not only on the neck, but also under the arms, between the thighs, around the fingers and toes, and even on the elbows or knees.

Doctors warn that if you notice this kind of skin change, it could be a red flag that your body isn’t processing insulin properly. And when insulin isn’t doing its job, the risk of developing type 2 diabetes increases significantly.

What Is the Dark Ring Around the Neck?

Dr. Alyne Ricker, a pediatric endocrinologist at the Joslin Diabetes Center in Boston, explains that this condition is known as acanthosis nigricans.

It’s a common skin reaction when the body produces too much insulin — a hallmark of type 2 diabetes. “When your body starts pumping out too much insulin—which is common with type 2—receptors in the skin folds respond by making extra pigment,” Dr. Ricker says.