If you or someone you know has dark, velvety patches of skin—especially on the back of the neck or under the arms—it might be easy to assume they’re caused by dirt or friction. But these patches could be an early warning sign of something more serious.
This condition is called Acanthosis Nigricans, and it’s often linked to insulin resistance and high blood sugar. Recognizing it early can help prevent more severe issues such as type 2 diabetes.
What Is Acanthosis Nigricans?
Acanthosis Nigricans appears as darkened, thickened, and velvety skin, most commonly found in areas like:
The back of the neck
The armpits
The groin
These patches may feel soft or textured, and sometimes there’s increased hair growth. They cannot be washed off, and their appearance is not related to hygiene.
What Causes It?
Acanthosis Nigricans isn’t a disease itself—it’s a symptom that points to something else going on in the body. Common causes include:
Insulin resistance, often seen in people with prediabetes or type 2 diabetes
Obesity, especially in children and teenagers
Hormonal imbalances
Genetic factors
Certain medications or, rarely, tumors
Doctors warn that people with obesity who develop this skin condition are at higher risk of progressing to diabetes, making it an important early red flag.
Expert Insight
Dr. Hafizah Mohamed, a physician and member of the #medtweetMY health initiative, recently emphasized that dark skin patches on a child’s neck can indicate rising blood sugar levels.
“This isn’t dead skin buildup. If your child or anyone you know has these dark patches, it might be time to check their blood sugar,” she advised.
She also noted that the patches usually aren’t itchy or painful. If the area becomes red, sore, or itchy, another condition—such as eczema—could be to blame.
How to Check Blood Sugar
Many pharmacies offer quick blood glucose tests, and home meters are easy to find. If you notice suspicious skin changes, consult a healthcare provider for proper testing. Early blood sugar monitoring can detect prediabetes and allow for lifestyle changes before serious complications develop.
Other Conditions That Look Similar
Not all dark patches are Acanthosis Nigricans. Terra Firma-Forme Dermatosis (TFFD) looks similar but can often be wiped off with 70% isopropyl alcohol. If your dark patches don’t wash off, see a doctor for a proper diagnosis.
When to See a Doctor
You should seek medical advice if:
You or your child suddenly develop dark, thick skin patches
The patches spread or become irritated
You have a family history of diabetes
You notice other symptoms like frequent urination, thirst, or fatigue
Early diagnosis can make a huge difference in long-term health.
Prevention and Lifestyle Tips
If Acanthosis Nigricans is linked to insulin resistance or weight issues, the following steps may help reduce or prevent it:
Eat a balanced diet with whole grains, lean protein, and vegetables
Exercise for at least 30 minutes most days
Maintain a healthy weight
Cut back on sugary drinks and processed foods
Get regular checkups for blood sugar and cholesterol
In some cases, dermatologists may prescribe creams or treatments to lighten the patches, but addressing the underlying cause—such as insulin resistance—is the real solution.
Final Thoughts
Dark patches on the neck or underarms may look harmless, but they can be the body’s way of signaling a deeper issue like insulin resistance or metabolic imbalance.
Don’t ignore these changes. Talk to your doctor, get tested, and take charge of your health. Early awareness and lifestyle improvements can make all the difference for your long-term well-being.