Insulin (Fasting)

Hormones

Sex Hormone Metabolism

Fasting insulin measures the amount of insulin circulating after an overnight fast, reflecting how hard the pancreas is working to keep blood sugar controlled. As the master metabolic hormone, insulin governs glucose handling, fat storage, protein synthesis, and cellular growth. A longevity practice prizes it as one of the earliest signals of metabolic dysfunction, often shifting before glucose does.

What It Measures

Master metabolic hormone; regulates glucose, fat storage, protein synthesis, and cellular growth

Optimal vs. Lab Range

Longevity Optimal

2–6 µIU/mL

Target range for optimal health and longevity based on research.

Standard Lab

2.6–24.9 µIU/mL

Population-based reference range from standard labs.

Why It Matters

Fasting insulin can reveal insulin resistance years before fasting glucose or HbA1c become abnormal, making it a powerful early-warning marker for healthspan. Elevated levels are associated with insulin resistance, metabolic syndrome, type 2 diabetes, PCOS, obesity, increased cardiovascular and cancer risk, and accelerated aging. Low fasting insulin, by contrast, may reflect type 1 diabetes, late-stage beta-cell exhaustion, or, rarely, an insulinoma. Because insulin sits upstream of so many age-related conditions, keeping it in a healthy range is central to metabolic longevity. It is best interpreted with fasting glucose, HbA1c, HOMA-IR, triglycerides, and the triglyceride-to-HDL ratio.

When Low

Type 1 diabetes, beta cell exhaustion (late T2D), insulinoma (rare)

When High

Insulin resistance, metabolic syndrome, type 2 diabetes, PCOS, obesity, increased cancer and cardiovascular risk, accelerated aging

How to Optimize

Lifestyle changes are especially effective here: time-restricted eating, lower-carbohydrate nutrition, zone 2 exercise, quality sleep, and stress management all improve insulin sensitivity. Some patients use berberine, and metformin may be considered under physician direction. Because insulin responds strongly to daily habits, consistent behavior change often shifts this marker meaningfully. Hormone testing and treatment must be individualized with your physician; this content is educational and not a substitute for medical advice.

Key Interventions & Linked Compounds

Strong evidence

Key Interventions

Time-restricted eating

low-carb diet

zone 2 exercise

berberine

metformin (clinical)

sleep optimization

stress management

Linked Compounds & Supplements

Berberine

Chromium

Alpha-lipoic acid

Myo-inositol

Cinnamon

Magnesium

Curated from clinical literature. Individual results vary; consult a qualified clinician before changing a protocol.

Ordering Notes

Specimen

Serum; saliva for diurnal cortisol panels

Patient prep

No fasting required. Maintain usual diet and medications unless advised.

Recommended cadence

Quarterly

Reporting unit

Confirm with the performing lab — units vary by region.

Pre-analytic notes

Standardize draw time of day, hydration, and recent exercise. Note any acute illness, supplements, or hormonal therapies on the requisition.

Recommended Follow-Up Actions

1
Confirm the result is reliable
Repeat abnormal values before acting — preferably from the same lab, same time of day, and under consistent prep. Rule out acute illness, recent intense exercise, or medication effects that can shift Insulin (Fasting).
2
Compare against optimal, not just lab range
Use the optimal window above as the target. Lab "normal" is built from the general population and often misses early dysfunction.
3
Pair with related markers
Order a complementary panel covering metabolic, inflammatory, and hormonal context to interpret this marker properly.
4
Discuss interventions with a clinician
Use the interpretation guidance above to frame the conversation. Bring trends, not just one datapoint, to your visit.
5
Re-test on a defined cadence
If a change is implemented, re-measure in 8–12 weeks for fast-moving markers, or 3–6 months for slower ones, to confirm response before escalating.