The TL;DR
Insulin is a hormone that shuttles energy (glucose) into cells. In a healthy state, it rises briefly after a meal and falls quickly. In a “Western” state, it remains chronically elevated (hyperinsulinemia), driving inflammation, fat storage, and cellular aging. Controlling insulin—keeping it low and sensitive—is arguably the single most important metabolic lever for extending healthspan.
Accessibility Level
Level 1 (Foundation): Understanding insulin is fundamental. You cannot optimize longevity while insulin resistant. Testing fasting insulin is cheap ($15-30), yet rarely done in standard physicals.
The Science of Insulin
Insulin is an anabolic (building) hormone secreted by the pancreas. Its primary job is to lower blood sugar by unlocking cells to receive glucose.
The Problem: Insulin Resistance
When you chronically overexpose your cells to insulin (via frequent eating, refined carbs, and inactivity), they stop listening. The pancreas then shouts louder (pumping out more insulin) to force the glucose in.
- Stage 1 (Silent): Normal blood sugar, but high insulin (Hyperinsulinemia).
- Stage 2 (Pre-Diabetes): High insulin can no longer keep up; blood sugar rises.
- Stage 3 (Type 2 Diabetes): Pancreatic failure and systemic metabolic collapse.
Insulin and Aging
Hyperinsulinemia is a pro-aging state. It:
- Inhibits Autophagy: Insulin signals “growth,” which blocks the cellular cleanup process (autophagy) needed for repair.
- Promotes Senescence: Chronic growth signaling drives cells into a “zombie” state (senescence).
- Drives Cancer: Many cancers feed on glucose and insulin signaling pathways (PI3K/AKT).
Evidence Matrix
| Source | Verdict | Notes |
|---|---|---|
| Dr. Joseph Kraft | ”Diabetes in Situ” | Showed that thousands of people with “normal” glucose had diabetic-level insulin responses. |
| Peter Attia | Critical Priority | Regards insulin resistance as the primary driver of the “Four Horsemen” of death. |
| Clinical Research | Strong Consensus | Hyperinsulinemia is independently associated with all-cause mortality, even in non-diabetics. |
Optimal Ranges
Standard lab ranges are dangerous because they are based on an increasingly sick population.
| Marker | Standard Range | Longevity Target |
|---|---|---|
| Fasting Insulin | < 25 uIU/mL | < 5 uIU/mL (Ideally 2-3) |
| HOMA-IR | < 2.0 | < 1.0 |
| Post-Prandial | n/a | Returns to baseline < 2 hours |
How to Optimize
- Diet: Minimize refined carbohydrates and sugar. Prioritize protein and healthy fats.
- Fasting: Time-Restricted Feeding (e.g., 16:8) gives insulin levels time to drop to baseline.
- Exercise: Zone 2 cardio improves mitochondrial efficiency; resistance training increases glucose disposal (giving insulin “somewhere to go”).
- Sleep: One night of sleep deprivation can induce acute insulin resistance.
References
Kraft, J. R. (1975). Detection of diabetes mellitus in situ (occult diabetes). Laboratory Medicine, 6(2), 10-22.
Facchini, F. S., Hua, N., Abbasi, F., & Reaven, G. M. (2001). Insulin resistance as a predictor of age-related diseases. The Journal of Clinical Endocrinology & Metabolism, 86(8), 3574-3578.
Dankner, R., et al. (2012). Basal-state hyperinsulinemia in healthy normoglycemic adults precedes dysglycemia and predicts diabetes. Diabetes Care, 35(8), 1698-1704.