A chapter of The Invisible Fire

Skin Tags.

Most of this series follows the fire into organs you can't see — the pancreas, the liver, the arteries. This short chapter is about one you can: the skin. Skin tags, and their cousin acanthosis nigricans, are among the few places the metabolic fire shows on the outside — a visible flag of high insulin, hiding in plain sight. Not a disease in themselves, but a sign worth reading.

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A sign, not a symptom

A window, not the disease.

Skin tags — the small, soft, hanging growths doctors call acrochordons — are so common and so harmless that they're usually waved away as a cosmetic triviality. And as growths, they are trivial: benign, painless, of no danger. But that dismissal misses something useful. A skin tag is not just a bit of loose skin; for many people it's a small outward sign of an inward metabolic state — one of the very few you can spot without a blood test.

Insulin isn't only a fuel switch — it's a growth signal. And skin shows growth readily.
For education only. Not medical advice. Skin tags are harmless and extremely common, and having them does not mean you have any disease. This chapter describes an association, not a certainty — and anything about your skin or your metabolic health belongs with a doctor who can actually examine and test you.
Question One
What are they, and what travels with them?

Skin tags are small, soft growths that hang from the skin on a narrow stalk, favouring the places where skin rubs and folds: the neck, the armpits, the groin, the eyelids. They're benign, and they become more common with age and with weight.

They often keep company with acanthosis nigricans — patches of thickened, velvety, darkened skin in the same folds, especially the back and sides of the neck. The two frequently appear together, and for a shared reason: both are skin's response to high insulin. Acanthosis nigricans in particular is a well-recognised clinical marker of insulin resistance — dermatologists are taught to see it and think metabolic.

Question Two
Why does insulin grow them?

At high concentrations insulin acts on the skin — partly through its own receptors, partly by cross-activating receptors for IGF-1, a growth-driving cousin — pushing skin cells to proliferate. Raise the insulin and watch the skin respond. Then try the button.

Read the sign
Drag insulin up. Tags appear, the neck darkens — and the internal fire rises with them. Then remove the tags, and watch what happens to the fire.
NECK & FOLDS
what you see in the mirror
Insulin — the fire underneathLow
Insulin levelLow
Illustrative — a schematic of the association, not a medical picture or a diagnostic tool.

That's the whole lesson in one gesture. Removing the tags clears what you see and changes nothing underneath — like wiping a warning light without checking the engine. The sign was never the disease.

Honestly — an association, and how strong

What the evidence actually says.

This is where the series' discipline applies, because the skin-tag story is easy to overstate. What the evidence shows is an association: multiple case-control studies find that people with skin tags are more likely to have impaired carbohydrate metabolism — higher insulin, higher blood sugar, a higher rate of the metabolic syndrome — than people without.[1][2] The link is stronger the more tags a person has, and stronger still when acanthosis nigricans is present too.[3]

What this does and doesn't mean. It does not mean a skin tag proves insulin resistance — plenty of people have a tag or two with perfectly normal metabolism, and the growths are influenced by age, friction and genetics too. And these are observational studies: they show the two travel together, not a proven one-way cause. What it does mean is that multiple tags, particularly with neck darkening, are a reasonable prompt to check the metabolic picture underneath — a visible nudge to look, not a diagnosis on their own.
Question Three
How should you read them?

Because skin tags are a sign rather than a disease, the useful response isn't on the skin at all.

  • Treat them as a flag, not a target — several tags, especially with velvety neck darkening, are worth mentioning to a doctor as a reason to look at fasting insulin, glucose and the metabolic picture.
  • The lever, if the picture is metabolic, is the familiar one — lowering the insulin load. As insulin resistance improves, acanthosis nigricans in particular can visibly fade — a satisfying confirmation that the skin was reading the insulin.
  • Remove for comfort or cosmetics if you wish — that's fine and safe, but understand it's grooming, not treatment; it does nothing to the metabolic state that may have prompted them.
The honest caveat, and a real one. Any new, changing, bleeding, or unusual skin growth is not a skin tag to reason about — it needs a doctor's eye to rule out something that matters. Never diagnose your own skin from a web page. This chapter is about a common, benign growth as a metabolic sign; it's not a guide to telling one skin lesion from another, which is a job for a clinician.
Where this leaves you

A note the body leaves where you can see it.

Almost everything in this series is invisible — a hormone you can't feel, a fat you can't see, a pressure you can't sense. Skin tags are a small exception: a place where the fire, sometimes, shows on the surface. Insulin is a growth signal as well as a fuel switch, and where it runs high it can prompt the skin to grow these little flags — and darken in the folds — in a way that travels, statistically, with the metabolic state underneath.

Not a disease to treat on the skin — a visible prompt to look at the insulin beneath.

Ask your body what the skin is reading — then look underneath the sign.

One of the few visible faces of the one fire. Back to the whole: The Invisible Fire.

A final word

Modest, and useful at once.

The right way to read them is modest and useful at the same time: not as a disease to treat on the skin, and not as proof of anything on their own, but as a visible prompt — one of the few this series offers — to look at the insulin beneath.

Not a disease — a sign. One of the few places the fire writes itself on the surface.

Verified references

These are observational studies — they establish association, which is exactly the claim this chapter makes.

[1] Rasi A, Soltani-Arabshahi R, Shahbazi N (2007). Skin tag as a cutaneous marker for impaired carbohydrate metabolism: a case-control study. Int J Dermatol 46(11):1155-1159. PMID 17988334. Read →

[2] Acrochordons as a cutaneous sign of metabolic syndrome: a case-control study (2014). Ann Med Health Sci Res 4(2):202-205. PMID 24761238. PMC3991940. Read →

[3] Screening of glucose/insulin metabolic alterations in men with multiple skin tags on the neck, including acanthosis nigricans (2008). PMID 18397315. Read →