Hyperinsulinemia: Unmasking the Silent Driver of Chronic Disease

NOTE: This article was originally posted on December 5, 2018, and was updated and reposted on April 19, 2026.

Practitioner’s Preface

High insulin levels and insulin resistance work together in a damaging circle that harms health. When cells stop responding to insulin, blood sugar rises, forcing the body to produce even more insulin. Over time, this constant cycle causes silent damage and acts as the main driver for many long-term health conditions.

Insulin resistance and hyperinsulinemia (too much insulin) are often lumped together, but they are different conditions that work in a cycle. To understand the risk they pose, we first have to look at how the body manages energy.

Normally, blood glucose (also called “blood sugar”) is tightly regulated between 3.9–5.5 mmol/L (70–100 mg/dl). When someone eats, their blood sugar rises as the body breaks down carbohydrates. This triggers the hormone insulin to be released from the beta cells of the pancreas. Think of insulin as a key that signals the muscle and fat cells to unlock and enable sugar to move out of the blood, so that it can be used for energy.

• Hyperinsulinemia literally means “too much insulin.” It occurs when the beta-cells of the pancreas secrete too much of the hormone. While this can happen in response to high blood sugar (hyperglycemia), as I wrote about in this 2018 article, we have known for almost a decade that chronically elevated levels of insulin often come before abnormal blood sugar levels [1][2][3].

• Insulin resistance occurs when the cells of the body stop responding to insulin signals. When the body is flooded with too much insulin for too long, the cells “lock the doors” to protect the body from being overwhelmed by too much glucose. As a result, that glucose remains in the blood, causing hyperglycemia (which means “too much glucose”).

When someone is insulin resistant, the sugar stays in the blood longer than it should, and this creates a cycle. The beta cells of the pancreas pump out even more insulin to try to force the excess sugar into the cells, which only makes the resistance worse. Over time, this “silent” cycle of high insulin and resistance becomes the primary driver for many of the chronic diseases we see today.

Why Is It Important to Treat High Insulin Early?

Treating high insulin levels early is vital because this hidden condition often develops years before blood sugar levels appear abnormal on standard medical tests. Focusing on the root cause helps manage metabolic disorders effectively. This early care helps protect long-term health and prevents the progression of serious chronic conditions.

In my almost 18 years of private clinical practice, I frequently see chronic health conditions that are now known to be related to hyperinsulinemia. When I first started writing about this topic in 2018, it was almost unheard of, even amongst many healthcare professionals, yet I have been focusing on the care of those with pre-diabetes and type 2 diabetes, as well as PCOS, related to the underlying high levels of insulin, compounded with the resulting insulin resistance. I have also written that Alzheimer’s disease is thought to have some common underlying mechanisms associated with type 2 diabetes, resulting in the term “type 3 diabetes”.

What Conditions Are Caused by Chronically High Insulin?

Chronically high insulin levels are now recognized as the main cause of several chronic diseases because it causes structural and functional damage throughout the body well before high blood sugar is detected. Affected areas include heart health, liver function, weight management, human reproduction, and brain function.

Current research has shifted the focus from hyperglycemia (high blood sugar) as the primary driver of disease to the structural and functional damage caused by hyperinsulinemia (high levels of circulating insulin).

Below is a list of diseases now recognized as being driven by chronic hyperinsulinemia:

How Does High Insulin Increase the Risk of Heart Disease?

High insulin acts as a hidden trigger that forces the heart muscle to become thickened and stiff. This change leads to a specific type of heart failure where the heart cannot relax properly. This structural damage occurs silently even when standard blood sugar tests show perfectly normal results.

High insulin is considered to be a silent trigger for heart disease. It causes the heart muscle to thicken and stiffen, leading to a condition known as ‘heart failure with preserved left ventricular ejection fraction (HFpEF)’ that can occur even when blood sugar levels still appear normal [4].

What Is the Link Between High Insulin and PCOS?

High insulin is the main underlying driver of Polycystic Ovarian Syndrome (PCOS), a hormone imbalance that often leads to irregular periods. High insulin signals the ovaries to create too much testosterone, which disrupts reproductive health. This hormonal shift creates a cycle that worsens both metabolic health and reproductive symptoms over time.

As I wrote about in this 2026 article, hyperinsulinemia is now considered the upstream driver of Polycystic Ovarian Syndrome (PCOS). It is the high insulin levels that signal the ovaries to produce excess testosterone, creating a cycle that worsens both metabolic and reproductive symptoms [5].

How Does High Insulin Cause Fatty Liver Disease?

High insulin levels directly signal the liver to constantly create and store excess fat. This process causes severe swelling and irritation in the liver cells over time. Left unchecked, this fat buildup leads to permanent liver scarring and severely compromises overall metabolic health.

Metabolically Dysfunctional-Associated Steatotic Liver Disease (MASLD), previously known as Non-Alcoholic Fatty Liver Disease (NAFLD), is a condition driven by insulin’s signal to the liver to create and store fat. High insulin levels promote “de novo lipogenesis” (the creation of new fat), leading to inflammation and permanent liver scarring [6].

Why Is Alzheimer’s Disease Called Type 3 Diabetes?

Alzheimer’s disease is often referred to as “type 3 diabetes” because it involves severe insulin resistance inside the brain. This lack of insulin response causes brain swelling, cell stress, and a breakdown in communication between cells. These damaging processes eventually lead to brain cell death and memory decline.

As I wrote about in this 2018 article, Alzheimer’s disease has been called this because it is characterized by chronic insulin resistance of the brain. This leads to inflammation, oxidative stress, dysfunction in intercellular communication, and neuronal cell death; and these processes are what contribute to cognitive decline in neurodegenerative disorders such as Alzheimer’s disease.

How Do High Insulin Levels Lead to Weight Gain and Tumor Growth?

High insulin lowers blood sugar levels too much, which triggers intense hunger and drives people to eat more. Additionally, insulin acts as a powerful growth hormone. When levels stay high, it can speed up the growth of tumors by signaling cells to divide too quickly.

There is strong evidence to support the idea that hyperinsulinemia is a key factor in obesity [8]. The oversecretion of insulin, even at normal glucose levels, may lower blood glucose even further, stimulating eating

Insulin is a potent growth-promoting hormone. When levels are chronically high, it can act as “fertilizer” for tumors, specifically increasing the risk and progression of colorectal, breast, and pancreatic cancers by signaling cells to divide rapidly [8].

How Does Chronic High Insulin Lead to Type 2 Diabetes?

Eating too much (overnutrition) results in high insulin, which forces the body to store fat inside vital organs like the liver and pancreas. This constant flooding of insulin makes cells stop listening to its signals, resulting in cells becoming “deaf” to insulin, which drives the progression of type 2 diabetes [9].

Why Is Targeting High Insulin Key to Reversing Chronic Disease?

Cells build up resistance to insulin as a protective shield against a constant overabundance of the hormone. Because high insulin levels cause structural body damage long before blood sugar rises on lab tests, dietary strategies need to target insulin release directly. Current clinical evidence supports that it is not simply a matter of the body failing to use insulin, but that muscle and liver cells become resistant to insulin as a protective mechanism in response to a constant overabundance of the hormone.

By the time blood glucose levels rise high enough to be seen as abnormal on a standard lab test, the cycle of hyperinsulinemia has been causing structural and functional damage to the body for years. Since hyperinsulinemia is the primary driver of several metabolic diseases, it is also the primary target for dietary strategies that address the underlying hyperinsulinemia, rather than only managing blood glucose.

How Do Dietary Changes Help Manage High Insulin Levels?

Identifying the root causes of chronic disease allows for personalized dietary and lifestyle changes that lower health risks. For conditions like pre-diabetes, type 2 diabetes, and PCOS, success relies on reducing high insulin levels, and proactive Meal Plans can help protect brain health in people with a family history of Alzheimer’s.

Understanding fundamental drivers of chronic disease enables me, as a Dietitian, to address dietary and lifestyle changes to help lower risk, specifically addressing underlying hyperinsulinemia and resulting insulin resistance. In those with a family history of Alzheimer’s disease, I regularly explain what is known in this regard so that people can make dietary changes to help reduce hyperinsulinemia.

More Info

Specialized dietary support to lower high levels of circulating insulin and stabilize blood sugar will address metabolic health at the root. I have almost a decade of experience helping people do just that. Learn about me and the Comprehensive Dietary Package that I offer.

To your good health!

Joy

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Common Questions About High Insulin and Insulin Resistance

Understanding the difference between high insulin and insulin resistance helps clarify how metabolic health breaks down over time. While these conditions are closely connected, identifying them early allows for better dietary choices. Finding answers to common questions clarifies how the body manages energy and stays healthy.

Q: What is the difference between hyperinsulinemia and insulin resistance?

A: Hyperinsulinemia is too much insulin in the blood. Insulin resistance is when cells stop responding to insulin’s signal, eventually forcing the pancreas to pump out even more insulin in a damaging cycle.

Q: Can you have high insulin with normal blood sugar?

A: Yes. Chronically elevated insulin levels often precede abnormal blood sugar levels by years, causing structural damage while glucose levels still appear normal on standard tests.

References

1. Crofts, C., Understanding and Diagnosing Hyperinsulinemia. 2015, AUT University: Auckland, New Zealand. p. 205.
2. Crofts CAP, Z.C., Wheldon MC, et al, Hyperinsulinemia: a unifying theory of chronic disease? Diabesity, 2015. 1(4): p. 34-43.
3. Crofts, C., et al., Identifying hyperinsulinaemia in the absence of impaired glucose tolerance: An examination of the Kraft database. Diabetes Res Clin Pract, 2016. 118: p. 50-7.
4. Fazio S and Carlomagno G (2026) Insulin resistance with associated hyperinsulinemia as a risk factor for the development and worsening of HFpEF. Front. Cardiovasc. Med. 13:1719492. doi: 10.3389/fcvm.2026.1719492
5. Houston EJ, Templeman NM. Reappraising the relationship between hyperinsulinemia and insulin resistance in PCOS. J Endocrinol. 2025 Mar 12;265(2):e240269. doi: 10.1530/JOE-24-0269. PMID: 40013621; PMCID: PMC11906131.
6. Bae JC. Metabolic Dysfunction-Associated Steatotic Liver Disease: The Role of Hepatic Steatosis in Insulin Resistance and Metabolic Health. Endocrinol Metab (Seoul). 2025 Apr;40(2):304-306. doi: 10.3803/EnM.2025.2340. Epub 2025 Mar 24. PMID: 40123045; PMCID: PMC12061749.
7. Chapple B, Bayliss E, Woodfin S, Smith M, Winter J, Moore W. Type 3 Diabetes: Linking Insulin Resistance to Cognitive Decline. Diseases. 2025; 13(11):359. https://doi.org/10.3390/diseases13110359
8. Thomas, D.D.; Corkey, B.E.; Istfan, N.W.; Apovian, C.M. Hyperinsulinemia: An Early Indicator of Metabolic Dysfunction. J. Endocr. Soc. 2019, 3, 1727–1747.
9. Janssen JAMJL. Overnutrition, Hyperinsulinemia and Ectopic Fat: It Is Time for A Paradigm Shift in the Management of Type 2 Diabetes. International Journal of Molecular Sciences. 2024; 25(10):5488. https://doi.org/10.3390/ijms25105488

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