What is insulin resistance?
Insulin resistance is when your cells stop responding well to insulin, so your body has to make more and more of it to keep blood sugar under control.
Imagine a door lock that's getting stiff. The key still works, but you have to push harder and harder to open it. Eventually, even pushing as hard as you can isn't enough. That's the path from insulin resistance to type 2 diabetes.
Why it matters for aging
Common drivers include fat stored inside the liver and muscles, a growing waistline, inactivity, too little muscle and poor sleep. It's extremely common: the CDC estimates more than a third of US adults have prediabetes, most without knowing it.
The good news is that it's often reversible, especially early. Exercise, building muscle, losing excess belly fat and sleeping well all make cells respond better to insulin.
A common myth
If your blood sugar is normal, you don't have insulin resistance.
In the early stages, the pancreas makes extra insulin, which keeps blood sugar normal for years while resistance builds. Tests of fasting insulin can catch it earlier.
Go deeper
Deep dives
- Early signs of insulin resistance, and what comes before them
- Berberine vs metformin: what the evidence actually says
Related terms
Updated Nov 9, 2026 · All terms