Why Fasting Insulin May Be the Most Important Blood Test Your Doctor Isn’t Ordering
When it comes to your health, most routine bloodwork includes the usual suspects: cholesterol, blood sugar (glucose), and maybe even hemoglobin A1C. But there’s one powerful marker that’s often left out — even though it can detect metabolic problems years before they show up on other tests.
That test is fasting insulin.
At Johnson County Integrative Medicine, we believe in looking deeper. We order fasting insulin for nearly every patient — because it gives us a window into how your body is handling sugar, energy, weight, and future disease risk. And yet, most conventional providers don't include it. Here’s why that needs to change.
What Is Fasting Insulin?
Insulin is a hormone made by your pancreas. Its job is to help move glucose (sugar) out of your bloodstream and into your cells, where it’s used for energy or stored.
After you eat, your insulin levels naturally rise. But when you're fasting (i.e., not eating for at least 8–12 hours), your insulin should be low. A fasting insulin test measures how much insulin is in your blood at baseline — and high levels can be a red flag, even if your blood sugar is “normal.”
Why Is Fasting Insulin So Important?
Because insulin resistance — when your body stops responding well to insulin — usually develops long before blood sugar starts to rise.
That means you could have:
A normal fasting glucose
A normal A1C
Normal cholesterol
…and still have dangerously high fasting insulin, putting you on the path toward:
Type 2 diabetes
Heart disease
Weight gain or difficulty losing weight
Polycystic ovarian syndrome (PCOS)
Fatty liver disease
High blood pressure
Insulin resistance is at the root of most chronic modern illnesses, yet goes unnoticed if no one is checking for it.
What Should Your Fasting Insulin Be?
While lab ranges may vary, most functional and integrative medicine providers aim for a fasting insulin between 2 and 5 µIU/mL.
Here’s a rough guide:
<2 – Possibly too low (may need further investigation)
2–5 – Optimal range
6–9 – Early insulin resistance
10+ – Significant insulin resistance
20+ – High risk for prediabetes, diabetes, and metabolic dysfunction
It’s not uncommon for us to see patients with fasting insulin levels in the teens or twenties — even though their regular labs look “fine.”
Why Don’t Most Doctors Check It?
There are a few reasons:
It’s not part of routine panels
Fasting insulin isn’t included in most standard blood work unless it’s specifically ordered.Focus is on blood sugar, not insulin
In conventional medicine, the focus is usually on fasting glucose or A1C to diagnose diabetes. But by the time these are elevated, you’ve already had high insulin for years.Insurance and coding barriers
Insurance companies may not cover fasting insulin unless there’s a strong reason. Unfortunately, “prevention” isn’t always considered a good enough reason in insurance-based care.Lack of awareness
Many providers simply haven’t been trained to use fasting insulin as an early metabolic risk marker, so they don’t think to order it.
How Do You Improve High Fasting Insulin?
While we won’t go into full treatment in this post, the main ways to reduce fasting insulin involve:
Stabilizing blood sugar with whole, unprocessed foods
Reducing added sugars and refined carbohydrates
Increasing protein, fiber, and healthy fats
Engaging in regular physical activity
Managing stress and improving sleep
Targeted supplements or medications (when appropriate)
Bottom Line: Fasting Insulin Can Catch Problems Early — If You Test It
You can’t fix what you’re not measuring.
At Johnson County Integrative Medicine, we go beyond the basics to look under the hood. We believe fasting insulin should be part of every metabolic screening, especially for those with a family history of diabetes, unexplained weight gain, fatigue, or difficulty losing weight. If you are located in Overland Park or surrounding areas and want advanced cardiometabolic screening. Book your appointment now!