Triglyceride-Glucose Index tests for insulin resistance and much more

Insulin resistance is not a good thing. 

Insulin resistance is when the liver and skeletal muscles do not respond to insulin, forcing the pancreas to produce more insulin to lower blood sugar. 

The problem with high insulin or hyperinsulinemia is that other organs like the fat tissue, liver, muscle, brain, bone, kidneys, and vasculature also respond to insulin.

Too much insulin can lead to diseases in those organs on top of hypertension, atherosclerosis, clot formation, and decreased cardiac function. I talked about those in my article, Hyperinsulinemia.  

A significant cause of insulin resistance is frequent meals or snacks that raise insulin. That is why even when insulin levels are high, it is not enough to lower blood sugar. This leads to chronic hyperglycemia or high blood sugar. 

Hyperglycemia triggers the formation of free radicals and oxidative stress and causes inflammation and cell damage.

Insulin resistance can also alter systemic lipid metabolism, leading to dyslipidemia. Dyslipidemia is comprised of described as (1) high levels of plasma triglycerides, (2) low levels of high-density lipoprotein (HDL), and (3) the appearance of small dense low-density lipoproteins.[1]

In short, insulin resistance and high insulin lead to everyday deadly diseases like coronary artery disease, cancer, strokes, adult-onset diabetes, and many others. 

I discussed them in Diseases Associated with the Metabolic Syndrome and The 80/20 Rule Applied to Diseases.

Measuring insulin resistance

If insulin resistance is that bad, how will you tell if you are insulin resistant?

The Hyperinsulinemic-euglycemic glucose clamp is the gold standard. It requires continuous insulin infusion, blood sugar monitoring, and intravenous glucose administration to maintain a predetermined blood sugar level. 

The problem with the euglycemic clamp is that it is not available outside research due to the complexity of the procedure, expense, and health insurance does not cover it. 

Other tests like the Homeostatic Model of Insulin Resistance or HOMA-IR use the fasting blood sugar and insulin levels; however, it is not routinely done. When was the last time you had your insulin levels checked?

Other measures of insulin resistance like the Quantitative Insulin Sensitivity Check Index (QUICKI), McAuley, Matsuda, Belfiore, Cederholm, Avignon, and Stumvoll indexes are more complicated.[2]

They use either the Oral Glucose Tolerance Test or blood insulin levels that are not tested if there is no suspicion of diabetes.

The Triglyceride-Glucose Index

In 2008, Mendía and colleagues devised a method that uses routinely ordered triglyceride and blood sugar levels.[3]

The following formula obtains the Triglyceride-Glucose Index. 

Ln (TG [mg/dL] x glucose [mg/dL]/2) or Logarithm of [Triglyceride mg/dl x fasting glucose mg/dL/2] 

An easy way to calculate the Triglyceride-Glucose index (TyG) is at MDApp. 

In Mendía et al.’s study, the best TyG index for diagnosis of insulin resistance was 4.65, which showed the highest true positive (sensitivity) of 84.0% and true negative or specificity of 45.0% when compared to the HOMA-IR. [3]

A study by Guerrero and colleagues compared the Triglyceride-Glucose Index with the Euglycemic clamp. They found that the TyG is comparable to the gold standard. 

The best value of the TyG index for diagnosis of insulin resistance was 4.68, which showed the highest sensitivity (96.5%) and specificity. In addition, the TyG index is helpful for both men and women, obese, non-diabetic, and diabetic individuals.[4]

Uses of Triglyceride-Glucose Index

Mendía et al.’s study showed that TyG predicts impaired fasting glucose and glucose intolerance or pre-diabetes.

A study from South Korea showed that a higher TyG index is a  predictor of severe COVID-19. I discussed that in Triglyceride-glucose index predicts the severity of COVID-19.

Another study showed that the higher the TyG index, the higher the incidence of cardiovascular diseases like coronary heart disease, peripheral arterial disease, strokes, deep vein thrombosis, and pulmonary embolism.[5]

A Singapore study on patients with an acute ischemic stroke showed a TyG index of ≥9.15 is associated with higher 90-day mortality and poor functional outcomes.[6]

TyG is also associated with thyroid disease. High TyG can be indicative of low thyroid hormone levels. [7]

Research from Turkey showed that the TyG index is higher in subjects with cardiac autonomic dysfunction, including abnormal cardiovascular response to exercise, postural hypotension, and cardiac denervation syndrome. [8]

But that is not all. A high TyG index is also associated with end-stage kidney disease, arterial stiffness, low vitamin D levels, non-alcoholic fatty liver, peripheral artery disease, poor outcomes in decompensated heart failure, and a higher risk of ischemic stroke.

What to do if the Triglyceride-Glucose index is high

The best and least expensive is intermittent fasting or time-restricted feeding. IF or TRE limits the amount of food intake to a certain number of hours. Fasting periods can last for 16, 18, 20, 36, or 44 hours.

• How to do Intermittent Fasting
• The Kaizen Way of Fasting
• Intermittent Fasting while on Diabetes Medications

During fasting, the body uses the stored fat inside the abdomen. As a result, the triglyceride and blood sugar decrease. 

Lower triglyceride and sugar result in a lower TyG index and a lower risk for all the conditions mentioned above. 

That applies the 80/20 principle, where a small activity accounts for most of the results. 

Read: The 20/80 Rule for Health

Another easy way to test for insulin resistance is The Triglyceride/HDL ratio detects insulin resistance and predicts diseases.

Prevention is simpler, cheaper, and has fewer complications than cure.

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References:

1. Thomas DD, Corkey BE, Istfan NW, Apovian CM. Hyperinsulinemia: An Early Indicator of Metabolic Dysfunction. J Endocr Soc. 2019 Jul 24;3(9):1727-1747. doi: 10.1210/js.2019-00065. PMID: 31528832; PMCID: PMC6735759.
2. Gutch M, et al. Assessment of insulin sensitivity/resistance. Indian J Endocrinol Metab. 2015 Jan-Feb;19(1):160-4. doi: 10.4103/2230-8210.146874. PMID: 25593845; PMCID: PMC4287763.
3. Simental-Mendía LE, et al. The product of fasting glucose and triglycerides as surrogate for identifying insulin resistance in apparently healthy subjects. Metab Syndr Relat Disord. 2008 Dec;6(4):299-304. doi: 10.1089/met.2008.0034. PMID: 19067533.
4. Guerrero-Romero, F et al. The Product of Triglycerides and Glucose, a Simple Measure of Insulin Sensitivity. Comparison with the Euglycemic-Hyperinsulinemic Clamp, The Journal of Clinical Endocrinology & Metabolism, Volume 95, Issue 7, 1 July 2010, Pages 3347–3351, https://doi.org/10.1210/jc.2010-0288
5. Li H, Zuo Y, Qian F, Chen S, Tian X, Wang P, Li X, Guo X, Wu S, Wang A. Triglyceride-glucose index variability and incident cardiovascular disease: a prospective cohort study. Cardiovasc Diabetol. 2022 Jun 10;21(1):105. doi: 10.1186/s12933-022-01541-5. PMID: 35689232; PMCID: PMC9188105.
6. Toh EMS, Lim AYL, Ming C, Yeo LLL, Sia CH, Tan BWQ, Leow AST, Ho JSY, Chan BPL, Sharma VK, Tan BYQ. Association of triglyceride-glucose index with clinical outcomes in patients with acute ischemic stroke receiving intravenous thrombolysis. Sci Rep. 2022 Jan 31;12(1):1596. doi: 10.1038/s41598-022-05467-6. PMID: 35102177; PMCID: PMC8803886.
7. Choi et al. Association between triglyceride-glucose index and thyroid function in euthyroid adults: The Korea National Health and Nutritional Examination Survey 2015. Plos One. July 15, 2021
8. Balcıoğlu AS et al. Triglyceride glucose index is related with cardiac autonomic dysfunction in patients with metabolic syndrome. Kardiologiia. 2022 Jun 30;62(6):45-50. doi: 10.18087/cardio.2022.6.n2049. PMID: 35834341.