In functional medicine, we are in no short supply of tests.

Given the opportunity, many clinicians would love nothing more than to run copious amounts of blood, saliva, urine, and stool samples to assess every aspect of their patients’ health. But the issue is that the cost of testing alone could reach thousands of dollars, and at that price, you better have a good reason why each test was chosen and how each will lead to better treatment.

When it comes to cardiovascular and metabolic testing, the standard lipid panel of TC, LDL-C, HDL-C, non-HDL-C and triglycerides, as well as hbA1c and fasting blood glucose, still serves as the main labs tracked, along with other metrics of metabolic syndrome such as waist-to-hip ratio and blood pressure. However, over the past few decades, the diagnostic ability of standard lipid and metabolic methodologies has been questioned.

Even worse, many labs have come out with a dizzying array of additional markers clinicians can choose from including, but not limited to:

  • Adiponectin
  • ApoA1
  • ApoB
  • C-peptide
  • Fibrinogen
  • GGT
  • hs-CRP
  • Homocysteine
  • Insulin
  • Leptin
  • Lp(a)
  • oxLDL
  • sdLDL
  • LDL-P
  • HDL-P
  • LpPLA-2
  • MPO
  • LDL particle size
  • HDL map
  • Omega-3 index
  • And more

Because of this, a lot of practitioners feel wary about including more advanced or less common tests for their patients, opting to rely on what they have always done.

This unfortunately can lead to an incomplete diagnostic analysis that misses early risk of more serious events and/or comorbidities down the road.

The good news is that two tests rise above the rest and should be prioritized to complement more commonly run labs. These are fasting insulin and ApoB testing.

Simplifying Advanced Cardiometabolic Testing 

As indicated above, adding advanced cardiometabolic testing gives you a dramatically improved ability to detect future cardiovascular events and downstream comorbidities. However, when the cost is a barrier for patients, you can forgo large expensive panels for select markers that provide more sensitive assessments of cardiometabolic health.

Fasting Insulin Test

By the time issues are showing up in an HbA1c measurement, the patient has been insulin-resistant for quite some time. Even when considering more sensitive tests such as an oral glucose tolerance test (OGTT), the time-consuming nature of this test results in many clinicians not opting for this screening tool for their diabetic and prediabetic patients.

Enter the fasting insulin test.

Fasting insulin allows a clinician to accurately assess for diabetic risk long before a diagnosis of type 2 diabetes occurs. In fact, fasting insulin has been shown to be a more sensitive predictor of cardiometabolic changes when compared to both HbA1c and fasting glucose.

Reference Range (uU/mL)

Low: < 5

Optimal: 5-15

High: >15

Clinical Pearl

Insulin levels above 9 uU/mL are highly predictive of prediabetes.

This measurement also gives clinicians the ability to utilize the HOMA-IR or homeostatic model assessment of insulin resistance, which is a calculation of fasting insulin and blood sugar levels used to assess insulin sensitivity.

ApoB Test

All potentially atherogenic lipoproteins, which include chylomicrons, VLDL, LDL, and Lp(a), contain an ApoB protein that acts as a ligand for the enzyme receptors responsible for clearing these lipoproteins from the blood. An ApoB measurement, therefore, can identify the number of particles in the blood that can potentially contribute to atherogenic plaquing.

Reference Range (mg/dL)

Optimal: <80

Borderline: 80-120

High: >120 

Clinical Pearl

In 2018, the American College of Cardiology and the American Heart Association acknowledged the superiority of ApoB testing in their guidelines, identifying it as a more accurate marker of cardiovascular risk when compared to LDL-C. There is also additional evidence to suggest that ApoB is more predictive than non-HDL-C.

This is good news for all the clinicians who are still on the fence about adopting new diagnostic measurements and are looking for an easy entry point for their practice.

The Bottom Line

While there have been great strides in the assessment of cardiometabolic disease from the early days of relying on total cholesterol, the basic approach to treatment has remained relatively constant. In all cases, individuals will need to quit smoking, increase physical activity and/or movement, improve the quality of their diets, incorporate personalized stress reduction techniques and avoid environmental exposure to common chemicals, pesticides, and heavy metals.

Using more advanced cardiometabolic testing, such as fasting insulin and ApoB, not only allows for better assessment of risk but also monitoring while the patient progresses through treatment.

  1. Johnson JL, Duick DS, Chui MA, Aldasouqi SA. Identifying prediabetes using fasting insulin levels. Endocrine Practice: Official Journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists. 2010;16(1):47-52. doi:10.4158/EP09031.OR
  2. Lakka HM, Lakka TA, Tuomilehto J, Sivenius J, Salonen JT. Hyperinsulinemia and the risk of cardiovascular death and acute coronary and cerebrovascular events in men: the Kuopio Ischaemic Heart Disease Risk Factor Study. Archives of Internal Medicine. 2000;160(8):1160-1168. doi:10.1001/archinte.160.8.1160
  3. Sniderman AD, Thanassoulis G, Glavinovic T, et al. Apolipoprotein B Particles and Cardiovascular Disease. JAMA Cardiology. Published online October 23, 2019. doi:10.1001/jamacardio.2019.3780
  4. Masternak MM, Panici JA, Bonkowski MS, Hughes LF, Bartke A. Insulin sensitivity as a key mediator of growth hormone actions on longevity. The Journals of Gerontology Series A, Biological Sciences and Medical Sciences. 2009;64(5):516-521. doi:10.1093/gerona/glp024

Steven Imgrund, MS, CNS Headshot

Steven Imgrund, MS, CNS

Steven Imgrund is a board-certified nutritionist and the CM Vitals Brand Manager at Lifestyle Matrix Resource Center, overseeing the marketing initiatives of their cardiometabolic product line. Steven developed his passion for nutrition and health working as personal trainer and health coach, specializing in weight loss and behavior change. Through working with hundreds of clients, Steven has seen the challenges with implementing long-term lifestyle and dietary habits. This experience has fueled his passion for functional medicine, and his desire to help health care practitioners use proven lifestyle and supplement strategies to safely address the root causes of their patients cardiometabolic issues. Steven received his Masters in Human Nutrition through Bridgeport University in 2018, and Certified Nutrition Specialist (CNS) certification in 2020.