David PerlmutterPresident,, Perlmutter Health Center · Board-Certified Neurologist | Functional Medicine Pioneer | #1 New York Times Best-Selling Author | International Speaker | Host of The Empowering Neurologist Podcast

Know This Before Getting Your Bloodwork Done

30 Jan 2026 · 2 min

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1:31

In this health‑advice monologue, Dr. David Perlmutter explains why fasting insulin, rather than just blood glucose, is a crucial early indicator of metabolic dysfunction. He describes insulin’s normal role in lowering blood sugar and how, when cells become insulin‑resistant, the pancreas compensates by secreting more insulin. Elevated fasting insulin can appear long before glucose levels rise, making it a superior marker for pre‑diabetes. He provides target fasting insulin ranges (2–5 µIU/mL is optimal; 8–10 µIU/mL suggests insulin resistance) and links high insulin to heightened risk of type 2 diabetes, Alzheimer’s disease, coronary artery disease, and other conditions. Finally, he urges listeners to proactively ask their physicians to include a fasting insulin test on their next blood work panel, offering a brief script for the conversation.

Chapters

Do you know your fasting insulin level? Well, you should. Insulin is, of course, the hormone created by the pancreas that helps lower our blood sugar, and it does a pretty good job of that in general until we develop something called insulin resistance, at which point the pancreas tries extra hard, secretes more insulin to get the blood sugar down. And we can measure that. We can see that higher levels of insulin are found in the body when people are starting to become resistant to its function. We call that insulin resistance. And that may happen long before the blood sugar goes up. So the idea of focusing just on the blood sugar is not as adequate as we can get in terms of predicting prediabetes, etc., by looking at the fasting insulin levels. So we want levels at around 2 to 5 micro international units per milliliter. Levels around 8 and 10 start to suggest insulin resistance, and that is the harbinger not just for type 2 diabetes but all the other things that come along with that, like dramatic increased risk for Alzheimer's disease, coronary artery disease, etc. So yes, we could focus on keeping our blood sugars intact and in an ideal range when we have our continuous glucose monitors, etc. But really, the home run lab measurement, in my opinion, is to understand what is your fasting insulin level. Next time you get blood work, you go to the doctor, say, "By the way, I'll be fasting. Please check my fasting insulin level." Now your doctor may ask why. Now you have an explanation. Bye bye, everybody.