By Easton Bryant, PharmD, Founder, North Century Pharmacy
A woman booked a consult with me recently. She was tired of being tired. Her doctor had run labs, and the answer she got back was the one I hear all the time: everything looks fine.
Her fasting blood sugar was 96. On most lab reports, that doesn't raise an eyebrow, and I understand why she was told she was fine. But when we looked at her fasting insulin too, it was 19.7.
If you read my article on insulin resistance in women, you've met her. Here I want to slow down and explain what that number means, because it's the part most people never get to hear.
My target for fasting insulin is 2 to 5. Her 19.7 is almost four times the top of that range. In plain language, her body was making almost four times the insulin I like to see, just to keep her blood sugar at 96.
Here's what's going on. Insulin is the hormone that moves sugar out of your blood and into your cells. When your cells stop responding well to it, your pancreas doesn't give up. It makes more, and then more again, until the job gets done. So her blood sugar looked calm because her pancreas was working overtime behind the scenes. A glucose test only shows the result. It doesn't show the effort.
That's why I get so frustrated when glucose is the only number on the page. And it's why this test matters.
What Does a Fasting Insulin Test Measure?
A fasting insulin test measures how much insulin is in your blood after an overnight fast. That tells you how hard your body is working to keep your blood sugar steady.
This matters because of what high insulin does. Starches and sugar drive insulin, and insulin drives fat storage. When your body stores energy away, it can't reach it, so it thinks it needs more. That's why high insulin and constant hunger so often go together. That can build for years before blood sugar changes, which is why insulin can show a problem long before glucose does.
I think about it this way: if you wait for glucose to move, you're finding out late.
How the Test Works
It's a simple blood draw, but a few things help you get a result you can trust.
You'll want to fast for 8 to 12 hours, which for most people means going to the lab first thing in the morning. A short fast or a late-night snack can push the number up and give you a false alarm. It also helps to skip any unusually hard workout for a day or two before.
If you plan to test again later, try to use the same lab. Insulin tests aren't standardized, so the same blood can give slightly different numbers at different labs. And if a result surprises you, don't panic. Repeat it under the same conditions before you decide what it means.
Most standard panels don't include fasting insulin. You usually have to ask for it by name.
Lab Ranges for Fasting Insulin Are Wide
This is the part that trips people up. One source puts the typical lab range for fasting insulin at roughly 2 to 20, and it varies from lab to lab. Look at how wide that is.
Depending on where she had her blood drawn, her 19.7 could have landed inside the printed range. No flag, no follow-up, and no one asking why her body needed that much insulin.
That's the idea behind one of my favorite sayings: normal isn't the same as optimal. A lab range is built to tell you whether you're sick. It isn't built to tell you whether your body is working easily or working hard. I aim for 2 to 5 because that's where I see people doing well.
I see this pattern in consults all the time. Someone sits down across from me who has been tired for years. Her labs have been run more than once, and she's been told everything looks fine. Then we look closer and find insulin creeping up and inflammation humming in the background. None of it was flagged. All of it was real.
9 Markers That Show How Your Body Handles Sugar (and Where They Get Missed or Misread)
Fasting insulin is one piece. Here are the numbers I look at together to understand how your body handles sugar and insulin, what each one tells me, and where each one tends to go wrong.
1. Fasting insulin
This is the earliest sign, and it's the one that's rarely ordered. It tells you how hard your pancreas is working. My aim: 2 to 5 mIU/L.
2. Fasting glucose
This is the number everyone checks, and it's a snapshot of one moment. Your body can hold it in range by making more insulin, so it can look fine while insulin climbs. Labs call anything under 100 normal. I aim for 70 to 85 mg/dL. It can also miss a lot on its own. In one study of a high-risk group, fasting glucose alone missed about half of the people with prediabetes or diabetes that a glucose tolerance test caught.
3. A1c
A1c is your average blood sugar over about two to three months. An average can hide the spikes after meals, so someone can have real swings and still land in a comfortable middle. It can also be thrown off. Iron deficiency anemia can raise it, blood loss can lower it, and some inherited hemoglobin variants and kidney disease can skew it. Her 6.0 sits in the prediabetes range.
4. HOMA-IR
This is a score that puts fasting insulin and fasting glucose together, so it can catch what either number alone might miss. To figure it out, multiply your fasting insulin by your fasting glucose (in mg/dL) and divide by 405. For her, that's 19.7 × 96 ÷ 405, or about 4.7. Cutoffs vary by lab and source, and many flag scores above about 2 to 3, so think of it as a conversation starter with your provider, not a diagnosis.
5. Triglycerides
When you take in more sugar than your body can use, it turns the extra into fat, and that fat shows up as triglycerides. Labs call under 150 normal. I aim for under 80. They can climb with insulin resistance before your glucose changes.
6. Triglyceride-to-HDL ratio
This is my favorite trick when someone doesn't have a fasting insulin value. Look at your most recent lipid panel and divide your triglycerides by your HDL. Triglycerides of 125 with an HDL of 40 isn't great. Triglycerides of 75 with an HDL of 50 is much better. Over 3 is a strong signal that insulin resistance has shown up, and I aim for under 1.5. It's a clue, not a test, but it costs nothing extra.
7. Uric acid
Fructose, especially from high fructose corn syrup, turns into uric acid, and uric acid can lower nitric oxide, which can raise blood pressure. It tends to travel with insulin resistance too. It's often called "normal" without any context. For women, I like to see it toward the lower end of normal. Hers was 7.0. More in our article on High Uric Acid.
8. Liver enzymes (ALT)
Fat in the liver and insulin resistance feed each other, so the liver is part of this story. But many people with fatty liver have a normal ALT, so it's easy to feel reassured when you shouldn't be.
9. After-meal blood sugar
This is the most overlooked one, because a fasting test can't see it. If your fasting numbers look fine but you crash after meals or crave sweets in the afternoon, it's worth asking your provider about a glucose tolerance test or a continuous glucose monitor.
Waist size and blood pressure belong in this picture too. Labs don't flag them as part of a sugar workup, but they usually tell the same story.
Why Your Numbers Can Look Different Than You Expect
Here's something I want you to know before you get your results: a single number rarely tells the whole story, and it can move for reasons that have nothing to do with a problem.
A rough night of sleep can do it. Research shows that short sleep suppresses the hormone that tells you you're full and raises the one that makes you hungry. That's why a bad night can leave you desperately hungry the next day and reaching for sugar. Bad sleep is also one more nudge toward insulin resistance, so if you got four hours before your blood draw, it may show.
Stress can move your numbers. So can being sick, having a hard workout the day before, or not being fully fasted. A different lab, a different machine, or a different time of day can change the result too. And medications and health conditions can change what a number means, which is why I never want you reading your labs alone.
That's not a reason to avoid testing. It's a reason to look at the whole picture, and to test again before you decide what's going on. One number is a clue. A pattern is an answer.
What to Do With Your Results
First, take them to your provider. A lab result isn't a diagnosis, and I would never ask you to change a medication on your own.
Second, remember that you have more power here than you think. The foundations matter most: less added sugar and refined starch, a walk after meals, building some muscle, and good sleep. Sugar has been added to 74% of packaged foods, so none of this is your fault. But once you know, you can make better decisions.
Third, ask whether your fasting insulin, A1c, and lipid panel can be checked together, so you can see the pattern.
Fourth, plan to check again in about 90 days. That's long enough to see whether your changes are moving the numbers.
If you take diabetes medicine, talk to your provider before adding anything like berberine. We walk through that in Berberine vs. Metformin. Homocysteine is another marker that often gets overlooked, and we'll cover it in a future article.
If you'd like help making sense of your labs, that's what we do. You can join NCPlus, our membership with a community, ongoing education, and member pricing on pharmacist-led optimization consultations, where we go through your labs with you and build a plan around what they show.
Where to Start
Reading about fasting insulin, ApoB, and uric acid is one thing. Seeing your own numbers is what changes things. It’s the moment a vague feeling that something’s off turns into a clear picture of what to do next.
That’s what our app is for. NCPlus is our membership: a community where you can ask questions, and ongoing education from our pharmacists and dietitians, all in one place. Join, download the app, and you’ll have everything you need to take the next step. Join NCPlus now!
Inside, there are two ways to get going:
REFOCUS30 is how you see your numbers. It includes labs like fasting insulin, ApoB, uric acid, and inflammation markers, and it builds a plan around what they show. You start it right from the app.
The 7-DAY RESET is how you put your habits to work while your plan takes shape. It’s where I start most people, and as an NCPlus member you get an automatic 10% off.
Your numbers, a plan built around them, and a simple week to get going. That’s a real kick start, with a community and a pharmacist-led team behind you.
You’ve got this.
This article is for education and isn’t medical advice. Talk with your provider about your own health.
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