Do You Know Your Insulin Level?

People often keep close watch on their glucose numbers, but how many of us know our insulin level? Dr. Joseph Mercola says fasting insulin[1] is “the number that may best predict your sudden death.” Sounds important. But what does it mean?

Our bodies need some circulating insulin at all times, even when we don’t eat. Otherwise, our livers keep making glucose and dumping it into the blood. Livers do this to prevent blood glucose from going too low.

To get cutting-edge diabetes news, strategies for blood glucose management, nutrition tips, healthy recipes, and more delivered straight to your inbox, sign up for our free newsletters[2]!

So a fasting insulin level should never be 0, which it might be in a person with untreated Type 1. It shouldn’t go below 3. But a high insulin level is just as problematic. A high insulin level is a sign of insulin resistance[3] or prediabetes[4]. It can also signify early-stage Type 2.

According to Dr. Mercola, too much insulin promotes weight gain by storing fat. It promotes insulin resistance, lowers magnesium levels, and increases inflammation. It also tends to lower HDL (“good”) cholesterol and raise levels of LDL (“bad”) cholesterol.

All of these increase the risk of diabetes and heart disease. It may be that high insulin levels come before insulin resistance and help cause it.

If you already have diabetes, why should you know your insulin level? Mainly, it helps diagnose what is happening with you. Your blood glucose may be high[5], but how much of the problem is too little insulin? How much is insulin resistance?

A fasting insulin level test is valuable in several situations:

• Diagnosing prediabetes and metabolic syndrome. “Prediabetes” is one result of insulin resistance. Insulin resistance causes high cholesterol, high glucose, and high blood pressure. A high level of fasting insulin indicates insulin resistance and can encourage a person to make changes to lower it.

• Separating Type 2 from LADA (latent autoimmune diabetes of adults)[6]. A person with Type 2 might have a normal or even high fasting insulin level. A person with LADA[7] is typically low.

Why does it matter? A person with LADA is more likely to benefit from insulin injections. He may be able to avoid years of oral medications that don’t help him much.

• Seeing if a person diagnosed with Type 1 is still making some insulin. A recent study from the UK found that about three quarters of adults with Type 1 actually produce small amounts[8] of insulin. Knowing you have some good beta cells can affect therapy and give some hope of improvement. So an insulin level test could show you if you have some.

This finding also calls for more research. Why do some beta cells survive and function normally when most have been destroyed?

What should your numbers be?

Insulin is measured in “microunits per milliliter” (mcU/ml or mIU/ml). Unfortunately, there isn’t much agreement on what level is ideal. The website Health Central says 10–20. Dr. Mercola says less than 5.

A study in Arizona found that women with a fasting insulin level around 8.0 had twice the risk of prediabetes as did women with a level around 5.0. Women with a fasting insulin of 25 or so had five times the risk of prediabetes.

University of Washington researcher Stephen Guyenet writes that “The average insulin level in the US is 8.8 mIU/ml for men and 8.4 for women. Given the degree of metabolic dysfunction in this country, I think it’s safe to say that the ideal level of fasting insulin is probably below 8.4 uIU/mL…[Best] would be 2–6.”

How to lower insulin level

Lowering insulin levels seems pretty similar to lowering glucose. Authorities like Dr. Mercola say the key is to reduce intake of sugar[9] and grains. Those foods stimulate insulin production. Refined grains and fructose-sweetened drinks are the worst, he says. Better to eat fats and proteins.

Writing on, Andy Jackson has a somewhat different take. “Increase your intake of fresh fruits[10] and vegetables, whole grains and lean proteins,” he says. “Avoid processed and fast foods, which are high in sugar, fat, and salt.”

Exercise[11] also lowers insulin levels and insulin resistance.

So ultimately, testing for insulin levels isn’t an earthshaking idea. It’s mainly important for diagnosis, especially of LADA. It’s also a powerful screen for risk of Type 2.

Since most people with or without diabetes have never had the test, it may be worth asking for. You’ll get a better idea of what’s happening with you. But for day-to-day monitoring, glucose testing is just as good as insulin testing.

Want to learn more about diabetes lab test results? Read “Understanding Your Lab Test Results,”[12] by Clinical Laboratory Scientist Judith Grout.

  1. fasting insulin:
  2. sign up for our free newsletters:
  3. insulin resistance:
  4. prediabetes:
  5. blood glucose may be high:
  6. LADA (latent autoimmune diabetes of adults):
  7. person with LADA:
  8. produce small amounts:
  9. reduce intake of sugar:
  10. intake of fresh fruits:
  11. Exercise:
  12. “Understanding Your Lab Test Results,”:

Source URL:

David Spero: David Spero has been a nurse for 40 years and has lived with multiple sclerosis for 30 years. He is the author of four books: The Art of Getting Well: Maximizing Health When You Have a Chronic Illness (Hunter House 2002), Diabetes: Sugar-coated Crisis — Who Gets It, Who Profits, and How to Stop It (New Society 2006, Diabetes Heroes (Jim Healthy 2014), and The Inn by the Healing Path: Stories on the road to wellness (Smashwords 2015.) He writes for Diabetes Self-Management and Pain-Free Living (formerly Arthritis Self-Management) magazines. His website is His blog is

Disclaimer of Medical Advice: Statements and opinions expressed on this Web site are those of the authors and not necessarily those of the publishers or advertisers. The information, which comes from qualified medical writers, does not constitute medical advice or recommendation of any kind, and you should not rely on any information contained in such posts or comments to replace consultations with your qualified health care professionals to meet your individual needs.