Diabetic Acanthosis Nigricans
Acanthosis nigricans (AN) is an inherited or acquired skin change in which body folds become darker and thicker with a velvety texture. In the setting of metabolic disease, AN is considered the most sensitive and earliest visible skin sign of insulin resistance, prediabetes or non-insulin-dependent type 2 diabetes.
What happens at the cellular level:
- In people with obesity, prediabetes or type 2 diabetes, muscle and fat cells respond less to insulin, so the pancreas compensates by releasing more and more insulin, resulting in chronically high blood insulin (hyperinsulinemia).
- At very high concentrations, insulin spills over from its usual receptor and binds directly to insulin-like growth factor 1 receptors (IGF-1R) on keratinocytes and fibroblasts in the epidermis and upper dermis.
- Activation of the IGF-1R pathway drives keratinocytes to overproliferate (thickening the epidermis and causing papillomatosis) and increases extracellular matrix production, creating the characteristic raised, velvety surface.
- In skin folds such as the armpits and neck, friction and sweat add to the problem, worsening keratinization and the buildup of brown-black pigment.
Recognizing acanthosis nigricans is about more than appearance: it gives dermatologists a chance to pick up diabetes risk early. At Haute-Derma, we take an integrated medical approach to diabetic acanthosis nigricans, addressing the underlying metabolic cause while safely and effectively restoring the look of the skin.
Clinical Features and Grading of Acanthosis Nigricans
Diabetic acanthosis nigricans develops quietly, without pain or itching, but it has a very recognizable appearance:
- Typical Locations:
- Back and sides of the neck: The most common site (>90%). The changes wrap around the nape and sides of the neck as a brown-black band that looks like dirt that will not wash off.
- Major skin folds: Armpits, groin, under the breasts, elbows and behind the knees.
- Knuckles: Thick, gray-brown skin over the backs of the finger joints, easily mistaken for calluses from rubbing.
- Appearance:
- Hyperpigmentation: Color ranges from light gray and gray-brown to deep black.
- Velvety surface: The skin is slightly raised and rough, with small papillae or deep creases, yet feels soft and smooth to the touch, like velvet.
- Skin tags (acrochordons): Very often accompanied by numerous small skin tags scattered over the neck and armpits.
- Clinical Grading (Burke Scale):
- Grade 0: No changes visible to the naked eye.
- Grade 1 (mild): Faint darkening and slight velvetiness confined to small areas within the folds.
- Grade 2 (moderate): Clearly thickened, velvety plaques that stay within the folds.
- Grade 3 (severe): Dark, thick velvety plaques that extend beyond the folds (for example, from the armpit onto the chest or from the neck onto the shoulders).
- Grade 4 (very severe): Widespread changes that can involve skin outside the folds and the mucous membranes.
Diabetic Acanthosis Nigricans vs. Other Forms
| Feature | Diabetic / Insulin-Resistance AN | Malignant AN |
|---|---|---|
| Underlying cause | Insulin resistance, hyperinsulinemia, type 2 diabetes | Gastrointestinal adenocarcinoma (especially stomach cancer) |
| Speed of progression | Slow, gradual over many years | Very rapid onset with sudden spread |
| Location and extent | Neck folds, armpits, groin, knuckles | Folds all over the body, palms (tripe palms), inside the mouth |
| Associated features | Obesity, darkened folds, skin tags | Rapid weight loss, loss of appetite, mucosal lesions |
| Response to washing | Does not come off with scrubbing | Does not come off with scrubbing |
Our Approach to Treating Acanthosis Nigricans at Haute-Derma
At Haute-Derma, treating diabetic acanthosis nigricans means correcting the underlying metabolic problem and restoring the skin surface at the same time:
Medical Screening and Metabolic Assessment
When a patient comes to Haute-Derma with AN, the doctor orders a standard metabolic panel:
- Insulin resistance index: Fasting insulin and fasting glucose are measured to calculate HOMA-IR. A HOMA-IR above 2.5 confirms significant insulin resistance.
- Blood sugar and lipids: HbA1c, fasting glucose, triglycerides and HDL cholesterol.
- Screening for related conditions: Polycystic ovary syndrome (PCOS) in women, or Cushing's syndrome if there is excess hair growth or purple stretch marks.
Combined Treatment Plan at Haute-Derma
- Treating the Root Cause (Medication and Lifestyle):
- Guidance on a low-glycemic-load diet, cutting back on refined sugar and processed starches.
- Working with endocrinology to prescribe insulin-sensitizing medication (such as metformin) that lowers blood insulin and so removes the stimulus on IGF-1 receptors.
- Topical Treatment to Thin the Skin and Normalize Keratinization:
- Topical retinoids (tretinoin 0.05%–0.1% or adapalene 0.3%): Speed up keratinocyte turnover, reduce papillomatosis and thin the overgrown horny layer.
- Keratolytics: Lotions or creams with urea 10%–20%, salicylic acid 3%–6% or ammonium lactate 12% soften the thickened skin and gently loosen scale.
- Supporting Aesthetic Treatments at Haute-Derma:
- Chemical peels: AHA (glycolic acid 30%–50%) combined with low-strength TCA, applied under a doctor's supervision to remove built-up keratin and brighten the skin in the folds.
- Picosecond laser (PicoSure / PicoPlus): 1064 nm or 755 nm wavelengths break up pigment clusters in the epidermis with minimal heat, keeping the risk of post-inflammatory hyperpigmentation (PIH) low.
- Removing accompanying skin tags: Skin tags (acrochordons) on the neck and armpits are removed gently with a SuperPulse CO2 laser, with quick healing and minimal scarring.
What to Avoid When Treating Acanthosis Nigricans
- Do not scrub with brushes or loofahs: Vigorous scrubbing adds mechanical friction and can trigger a Koebner-type reaction, leaving the skin inflamed, thicker and darker (PIH).
- Do not self-treat with strong corticosteroid creams: Long-term topical steroids do not thin acanthosis nigricans; instead they cause skin atrophy and stretch marks and, if absorbed systemically, can worsen blood sugar control.
