Why Insulin Resistance Is The Biggest Silent Risk Factor For Heart Disease.
Why Insulin Resistance Is The Biggest Silent Risk Factor For Heart Disease.
Insulin resistance is a major risk factor for heart disease but is rarely formally tested.
Insulin resistance is a major risk factor for the leading causes of death, the leading one being cardiovascular disease.
Everyone sits somewhere on the scale of insulin sensitivity from very insulin sensitive to very insulin resistant at the point of type 2 diabetes.
Understanding where you sit on this continuum is a key part of defining your future risk of heart disease but also dementia, and many cancers.
In simple terms, if you are insulin sensitive, you are very effective at disposing of glucose from your bloodstream. If you are insulin resistant, you are less efficient, and in more severe cases, blood glucose levels start to rise above normal.
The problem is that insulin resistance progresses long before glucose levels rise and other markers, such as HBA1c, become abnormal.
When glucose levels start to rise, you are at every end of the scale, and the dam has essentially broken.
Unfortunately, only at this point do most people find out that their risk is increasing.
The key is to identify risk much earlier.
Some Risk Factors Matter More Than Others.
A condition is rarely driven by just one risk factor; it usually results from multiple risk factors acting together.
But insulin resistance arguably sits at the top of the pile in terms of significance.
When evaluating cardiovascular risk over a 20-year time frame, signals of insulin resistance (Lipoprotein IR) confers a 6-fold increase in risk compared to those who are insulin sensitive1.
When insulin resistance progresses to type 2 diabetes, that risk increases to a 10-fold increase in risk.
Measuring Insulin Resistance.
There are many ways to assess insulin resistance. Some complex. Some simple.
Insulin resistance is characterised by high blood insulin levels. It requires more insulin to dispose of blood glucose than someone who is insulin-sensitive.
Therefore, insulin resistance is characterised by increased blood insulin levels.
Assessing both blood insulin and glucose levels allows the calculation of a HOMA-IR score, which is an excellent marker of insulin resistance.
As HOMA-IR scores increase, so does the likelihood of both cardiovascular disease and early death2.
The higher the score, the higher the risk.
But What Causes Insulin Resistance?
The exact mechanisms of what causes insulin resistance are still debated, but one thing is clear: lifestyle plays a major role.
There are medications that can improve insulin resistance, but the biggest levers by far are modifying lifestyle factors.
Both in terms of reversing insulin resistance and preventing it in the first place.
Even young adults who scored high on adherence to good lifestyle metrics had evidence of insulin resistance 18% of the time3.
However, for those with a poor lifestyle score, that figure was nearly five times higher at 85%.
Assessing Insulin Resistance Without Measuring Blood Insulin Levels.
Although calculating a HOMA-IR score is an excellent way of assessing insulin resistance, it is rarely done.
Even when I try to get this test done for my patients, it is frequently not done for various reasons.
Although this is frustrating, there are other ways to estimate insulin resistance.
While these are less accurate and are markers of later-stage insulin resistance, they can be done using standard tests.
On the continuum of insulin resistance before the appearance of type 2 diabetes is metabolic syndrome.
Metabolic Syndrome is characterised by having any 3 of the following 5 features.
High Blood Pressure.
High Triglycerides.
Low HDL Cholesterol.
Elevated Blood Glucose.
Increased Waist Circumference. >102cm/40 inches - Males >88cm/35 inches - Females.
The more of these factors that are present the greater the likelihood of insulin resistance and also all the consequences that go with it.
An important point to note is that weight is not included in this list. The reason waist circumfernece is included is to assess the amount of visceral (belly) fat that a person has which is one of the biggest drivers of insulin resistance.
Even having one of the metabolic syndrome factors increases the risk of dying from heart disease by 73%4.
Having 3 of them while also having type 2 diabetes and existing coronary artery disease increases the risk of dying from heart disease by almost 8 fold.
Metabolic syndrome can be assessed easily and cheaply in any healthcare setting.
No fancy tests.
No expensive scans.
Just some standard blood tests and a tape measure are all that is needed.
Right now, you sit somewhere on the scale of insulin sensitive to insulin resistant.
Genetics play a role in where you sit on this scale, but the lifestyle factors that you choose to adopt arguably play an even bigger role.
The further along the line of insulin resistance you sit, the higher your risk of all the leading causes of death, including heart disease, dementia and many cancers5.
The question you need to ask is:
Where do I sit on that line & what does it mean for my future risk?
When You Are Ready, Here Is How We Can Help.
For an accessible and comprehensive overview of understanding and managing heart health, you can check out the best-selling book Heart. An Owner’s Guide.
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In Case You Missed Them:
Association of lipid, inflammatory, and metabolic biomarkers with age at onset for incident coronary heart disease in women. JAMA Cardiol 2021;6:437–47
Non-linear associations of HOMA2-IR with all-cause mortality in general populations: insights from NHANES 1999–2006. BMC Public Health 24, 574 (2024).
Associations Between Life's Essential 8 and Insulin Resistance Among Nondiabetic Adults. J Am Heart Assoc. 2024 Jun 21:e033997.
Impact of the metabolic syndrome on mortality from coronary heart disease, cardiovascular disease, and all causes in United States adults. Circulation. 2004 Sep 7;110(10):1245-50.
Insulin Resistance as a Predictor of Age-Related Diseases, The Journal of Clinical Endocrinology & Metabolism, Volume 86, Issue 8, 1 August 2001, Pages 3574–3578,
Excellent! Very important clinical topic.
Dr. Aseem Malhotra covers this extensively in his short book "The 21 Day Immunity Plan":
Metabolic health markers – the measurements
An individual is considered to have optimal metabolic health if their markers meet the following levels:
Average blood glucose (HbA1c) levels of less than 5.7%
Blood pressure lower than 120/80mmHg
Waist circumference of less than 102cm for a man; 88cm for a woman (for South Asians it’s less than
90cm for a man; 85cm for a woman)
Blood triglycerides levels that are less than 1.7mmol/litre ( < 150md/dl)
High-density lipoprotein cholesterol (HDL-C) levels that are greater than 1mmol/litre ( > 40mg/dl in
men and > 50mg/dl in women)
A person is considered to have metabolic syndrome when they fail to meet three of these optimal values, meaning for example that someone who has high blood pressure, high blood glucose and high triglycerides would be considered to be at the highest risk of experiencing health problems.