Many chronic diseases share a common root — one that often goes unnoticed for years: insulin resistance. While frequently discussed in relation to diabetes, insulin resistance plays a far broader role in human health, influencing everything from inflammation to cancer risk.
What Is Insulin Resistance?
Insulin is a hormone produced by the pancreas that helps regulate blood sugar (glucose). Insulin resistance occurs when cells become less responsive to insulin. As a result, the body must produce more insulin to achieve the same effect, blood sugar levels begin to rise, and chronically elevated insulin (hyperinsulinemia) develops. Over time, this can progress to prediabetes and eventually type 2 diabetes — but the impact begins long before diagnosis.
Why Does Insulin Resistance Develop?
Insulin resistance is caused by a combination of lifestyle and metabolic influences: excess intake of refined carbohydrates and sugar, sedentary lifestyle, chronic stress and elevated cortisol, poor sleep, visceral (abdominal) fat accumulation, and chronic low-grade inflammation. From a metabolic perspective, it is the body's way of signaling that it is overwhelmed by excess energy and inflammatory stress.
The Link to Chronic Disease
Insulin resistance is now recognized as a central driver of type 2 diabetes, cardiovascular disease, non-alcoholic fatty liver disease, polycystic ovary syndrome (PCOS), and neurodegenerative diseases such as Alzheimer's — sometimes referred to as "type 3 diabetes." One of the key mechanisms behind these conditions is chronic inflammation, which is both a cause and consequence of insulin resistance.
Insulin Resistance and Cancer: What Is the Connection?
Elevated Insulin Promotes Tumor Growth. Insulin is not just a metabolic hormone — it is also a growth signal. High insulin levels stimulate cell proliferation, inhibit apoptosis (programmed cell death), and activate pathways such as IGF-1 (Insulin-like Growth Factor 1). These effects can create an environment that supports tumor growth.
Increased Inflammation. Insulin resistance is associated with chronic, low-grade inflammation, which contributes to DNA damage, cellular instability, and tumor initiation and progression. Inflammation is now considered a hallmark of cancer biology.
Altered Cellular Metabolism. Cancer cells thrive in environments with abundant glucose. In insulin-resistant states, blood glucose levels are often elevated, providing a steady fuel supply that tumors may exploit.