Most bloodwork panels don't include fasting insulin. Most doctors don't order it. And most women who eventually develop metabolic issues affecting their skin had fasting insulin that was quietly high for years before their glucose or HbA1c ever showed a problem.
That's the whole reason we put it on the JenSkin panel.
What fasting insulin actually measures.
Insulin is the hormone your pancreas releases to move sugar out of your blood and into your cells. When you eat carbohydrates, blood sugar rises, insulin comes in, moves the sugar where it belongs, and blood sugar returns to baseline.
That's the intended flow. It's supposed to happen a few times a day and then quiet down.
Fasting insulin measures how much insulin your body is producing when there's no food in your system. Ideally: not much. Your blood sugar is stable, no incoming carbs, no need for insulin to be doing heavy lifting.
But in a growing number of adults — especially women in their thirties, forties, and beyond — fasting insulin has crept up. The pancreas is producing more and more insulin just to keep glucose stable. The body is working harder to stay normal.
Think of it as an early warning system. The alarm is on. Not because there's a fire yet — but because something is starting to smolder.
Why this matters years before glucose does.
Elevated fasting insulin appears in bloodwork years — sometimes a decade — before fasting glucose starts to drift upward. The clinical pathologist Joseph Kraft documented this pattern most rigorously. His 1975 Laboratory Medicine paper on "occult diabetes," and his later 2008 book Diabetes Epidemic & You, showed that insulin dynamics revealed metabolic dysfunction in patients long before standard glucose measurements ever tipped abnormal.
By the time your fasting glucose is elevated, your pancreas has been working harder than it should for a long time.
We look at fasting insulin because it's the earliest signal of metabolic strain in your body. The earlier you know, the more leverage you have.
The skin story.
Chronically elevated fasting insulin drives three things that show up in your skin:
1. Increased sebum production and hormonal breakouts. Insulin stimulates the enzymes that produce oil in the skin. Women with elevated fasting insulin are the ones getting adult acne long past when their teenage skin should have stabilized.
2. Androgen activity. Insulin drives ovarian androgen production. That's the underlying mechanism in PCOS-related skin issues — chin hair, jawline acne, quality changes. The landmark 2012 Endocrine Reviews paper by Diamanti-Kandarakis and Dunaif established insulin resistance as the central mechanism in PCOS — and even women without a PCOS diagnosis but with elevated insulin often see this pattern in their skin.
3. Accelerated glycation. High insulin correlates with high blood sugar (even when the glucose reading itself is still "normal"). More sugar in the bloodstream means more sugar attaching to the collagen in your face.
The pattern that shows up on a woman in her late thirties: adult acne along the jawline, some chin hair she never used to have, and a slow, unexplained loss of skin firmness. Standard bloodwork looks "fine." Fasting insulin would have told the story years ago.
What fasting insulin responds to.
Same tools as glucose and HbA1c — but insulin adds one lever the others don't.
Strength training. Muscle is your body's largest sugar buffer. Trained muscle absorbs glucose from your blood without needing much insulin. The 2016 American Diabetes Association position statement on physical activity and diabetes, authored by Colberg and colleagues in Diabetes Care, confirms this: resistance training measurably improves insulin sensitivity independently of glucose control. Two to three short strength sessions a week is a real needle-mover.
Reduce refined carbohydrates. The predictable move for all three sugar markers. The less pancreatic work you demand, the lower fasting insulin trends.
Eat protein and vegetables first in a meal. Reduces the insulin surge from the carbs that follow. Small trick, real result.
Walk after meals. Muscles pull sugar out, insulin doesn't need to spike as high.
Consider Berberine or Metformin if appropriate. These are not recommendations from us — but they're the two interventions with real research on lowering fasting insulin in people who aren't responsive to lifestyle alone. Talk to your doctor.
Sleep. Chronic sleep deprivation raises fasting insulin. Non-negotiable.
The frame.
Fasting insulin is the earliest voice in the metabolic conversation. It speaks up before glucose does. It speaks up before HbA1c does. Most bloodwork will miss it entirely because most doctors don't order it.
That's why we include it. Not because everyone has a problem — most women don't — but because the ones who do deserve to know a decade before the rest of the system starts to fail.
The alarm is quiet. That's the point. If it's already loud, you've missed a lot of time you could have spent moving in a different direction.
References.
- Kraft JR. Diabetes Epidemic & You. Trafford Publishing; 2008.
- Kraft JR. "Detection of diabetes mellitus in situ (occult diabetes)." Laboratory Medicine. 1975;6(2):10-22.
- Diamanti-Kandarakis E, Dunaif A. "Insulin resistance and the polycystic ovary syndrome revisited: an update on mechanisms and implications." Endocrine Reviews. 2012;33(6):981-1030.
- Colberg SR, Sigal RJ, Yardley JE, et al. "Physical activity/exercise and diabetes: a position statement of the American Diabetes Association." Diabetes Care. 2016;39(11):2065-2079.
