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Insulin Response Test


Oral Glucose Tolerance Test (OGTT), is the test which can help diagnose instances of diabetes mellitus or insulin resistance. The test is a more substantial indicator of diabetes than finger prick testing.

The problem with this test is that usually by the time this test is prescribed the state of the disease and insulin resistance is already quite advanced in the patient.  Occasionally the OGTT is not sensitive enough and will miss many cases of sugar or insulin problems.

The test is used to determine whether the body has difficulty metabolising intake of sugar/carbohydrate.  The patient is asked to take a glucose drink and their blood glucose level is measured before and at intervals after the sugary drink is taken.

This can be a useful test in helping to diagnose:

  • Pre-diabetes

  • Gestational diabetes in pregnant women

  • Insulin resistance

  • Reactive hypoglycaemia

There are six stages of insulin resistance or diabesity. However, most healthcare practitioners will only act when a patient reaches the 5th state.

1st stage - high spiking levels of insulin 30 minutes, one hour, and two hours after the introduction of a sugar load. Your blood sugar may stay completely normal in these time frames.

2nd stage - elevated levels of fasting insulin with a perfectly normal blood sugar level while fasting and after a glucose challenge test.

3rd stage - the elevation of blood sugar and insulin after drinking glucose at 30 minutes, one hour, or two hours.

4th stage - an elevation of fasting blood sugar level greater than 90 mg/dl or 100 mg/dl and elevation of fasting insulin.

5th stage - the elevation of blood sugar level greater than 126 mg/dl.

6th stage - decreasing insulin levels and pancreatic burnout with increasing levels of blood sugar.




The test widely recommended by Functional and Integrative Medical Professional is a 2 hour Glucose Tolerance Test, with measurements of insulin and blood sugar checked after taking a 75gm load glucose (equivalent to the sugar quantity in two cans of Coke).

Prior to the test you will be required not to eat, or drink certain fluids, for up to 8 to 12 hours, and you may be asked to not take certain medications in the lead up to the test, but only if these would affect the test results.

For the test itself, you will first have blood taken to measure your blood glucose level before the taking the glucose drink. The next stage is to take a very sweet tasting, glucose drink.

Further blood samples will then be taken either at regular intervals of say 30 or 60 minutes or a single test after 2 hours. The test could take up to 3 hours.  Between blood tests you will need to wait so it’s best to have some reading material, or something else to keep you occupied, with you.

Recent studies have identified fasting and the 30-minute insulin and glucose test as a sensitive substitute to the two-hour test for diagnosing insulin resistance. Some people have a delayed insulin response, but the 30-minute test can be a quick way to do the test for most people.

There are no absolute consensus what the “normals” for these tests are, but here’s a good guideline to what is optimal or ideal Blood Sugar and insulin Levels:

  • Fasting blood sugar < 80mg/dl (4.44mmol/L)

  • 30 minutes, 60 minutes and 120 minutes ≤ 110mg/dl (6.11mmol/L) or maximum 120mg/dl (6.67mmol/L).

  • Fasting insulin between 2 and 5 mIU/dl; anything ≥ 10 mIU/dl is considered to be significantly elevated.

  • 30 minutes, 60 minutes and 120 minutes ≤ 25 mIU/dl to 30 mIU/dl. Anything ≥ is an indication of a certain degree of insulin resistance.


Please note that the figures recommended above are lower than the conventional ‘normal’ which is considered to be:


People without diabetes

  • Fasting value (before test): under 6mmol/L

  • At 2 hours: < 7.8mmol/L


People with impaired glucose tolerance (IGT)

  • Fasting value (before test): 6.0 to 7.0mmol/L

  • At 2 hours: 7.9 to 11.0mmol/L


Diabetic levels

  • Fasting value (before test): > 7.0mmol/L

  • At 2 hours: > 11.0mmol/L


The insulin response test is the most sensitive test available to identify insulin resistance and diabesity at an early stage and highlights the need for a more proactive approach to treatment and maintenance. The test can also be useful in patients with already diagnosed diabetes to establish whether they are still capable of producing insulin or they suffer from pancreatic burnout. This may influence recommended treatment. Occasionally, even a burnt-out pancreas can recover and diabetes can be reversed.  



 This test can tell us if overall blood sugar has been high over the past six weeks. It is used in monitoring diabetics but has now been proposed as a better way of diagnosing diabetes than just a random fasting blood sugar test.

 Despite the fact that your fasting blood sugar may be normal, your haemoglobin A1c can still be high, because it measures your average sugar, including the effects of all the food you consume throughout the day. This test should be used to screen for overall blood sugar balance.

For people without diabetes, the normal range for the haemoglobin A1c test is between 4% and 5.5%.  Haemoglobin A1c levels between 5.6% and 5.9% indicate increased risk of diabetes, and levels of 6.0% or higher indicate diabetes. Because studies have repeatedly shown that out-of-control diabetes results in complications from the disease, the goal for people with diabetes is a haemoglobin A1c below 7%. The higher the haemoglobin A1c, the higher the risks of developing complications related to diabetes.  Higher than 7.0% is considered poorly controlled diabetes.




Conventional Blood Cholesterol Testing

Conventional treatment for cholesterol focuses only on lowering LDL cholesterol with statins and the occasional change to lifestyle. It has been claimed by Functional and Integrative medical professionals that we measure and treat LDL because it is what we have the best available drugs for and not because it is the most important risk of cardiovascular disease. In fact LDL cholesterol is a very bad predictor of risk of heart disease when compared with total cholesterol-to-HDL ratio. And this is not as good a predictor as the triglyceride-to-HDL ratio (which incidentally is the best alternative to check for insulin resistance other than the insulin response test).


In fact, according to a paper published in Circulation (1992 Jan;85(1):37-45), the best test to predict risk of a heart attack is the ratio of triglycerides to HDL. If the ratio is high, then the risk of a heart attack increases 16-fold (1,600%).  This is due to the fact that triglycerides tend to go up and HDL (‘good’ cholesterol) tends to go down with diabesity.


Often, patients with diabesity may exhibit normal LDL and total cholesterol, but very high triglycerides and very low HDL. Therefore, it is not entirely unusual to see patients with triglycerides of 300mg/dl (16.67mmol/L) and HDL of 30mg/dl (1.67mmol/L). This should be considered much more of a concern than someone with total cholesterol of 300mg/dl (16.67mmol/L) and LDL of 140mg/dl (7.78mmol/L) but triglycerides of 60mg/dl (3.33mmol/L) and HDL of 80mg/dl (4.45mmol/L). Therefore assessing triglycerides and HDL correctly is critical. 


Optimal Cholesterol Levels

  • Total cholesterol < 180 mg/dl (10mmol/L)

  • LDL cholesterol < 70 mg/dl (3.89mmol/L)

  • HDL cholesterol > 60 mg/dl (3.33mmol/L)

  • Triglycerides < 100 mg/dl (5.56mmol/L)

  • Total cholesterol/HDL ratio < 3.0

  • Triglyceride to HDL ratio < 4.0


To reiterate, the traditional way of testing cholesterol can often be misleading. You may have a totally normal total cholesterol and LDL cholesterol and yet be at very high risk of a heart attack because it is the wrong type of cholesterol.  Interestingly, more than 50% of patients who show up in A&E with heart attacks display normal cholesterol test results. However, they have small cholesterol particles, which are caused by insulin resistance. There are, however, more comprehensive methods for testing cholesterol properly which I will discuss below.

Modern Cholesterol Tests

Newer tests examine not only the total amount of cholesterol, but also the actual size of the cholesterol particles and how many of them there are. Arguably, this is the only test for cholesterol that should be performed. Using conventional blood cholesterol testing is inadequate and past its sell-by-date. It is outdated, misleading, and often leads to prescriptions for medication which are needless and harmful.  It can also provide a false sense of security when cholesterol indicators are normal but the type of cholesterol particles is the small, dangerous variety. The newer cholesterol tests which are recommended are:


Nuclear Magnetic Resonance spectroscopy, or NMR lipid testing


It is performed by a laboratory called LipoScience. Many labs all over the world cooperate with this lab. This test is a much more sensitive, more precise indicator of the risk of heart disease than the total cholesterol or LDL cholesterol indicators you get from a regular cholesterol blood test.  Studies have found that despite the fact that some people might have a cholesterol level of 300mg/dl, if they have very large cholesterol particles they are still considered to have a very low risk of cardiovascular disease. Yet, people with a “normal” cholesterol level—such as 150 mg/dl—but very small and numerous LDL and HDL cholesterol particles have an extremely high risk of cardiovascular disease.


What causes these small dangerous cholesterol particles is the sugar and refined carbohydrates in our diet. Insulin resistance causes the formation of these small cholesterol particles, and taking statins is unlikely to solve the problem. The NMR test for cholesterol is one of the most crucial tests in evaluating the degree of insulin resistance and cardiovascular risk. Smaller particles means high risk. Light, fluffy cholesterol particles, on the other hand, are harmless and bounce off the arterial walls regardless of the overall LDL cholesterol value.


Optimal NMR Test Results

  • Total LDL particles < 1000nmol/L

  • Total small LDL particles < 600nmol/L

  • LDL size > 21nm

  • HDL size > 9mmol/L

  • VLDL < 0.1nmol/L

If you have any of the conditions listed below, the NMR LipoProfile® test may be appropriate: 

  • Diabetes

  • Previous heart attack

  • Family history of heart attack

  • High blood pressure

  • Overweight/Obesity

  • Cardio-metabolic risk

  • Metabolic syndrome

  • Low HDL (dyslipidaemia)

  • High triglycerides



Oxidised LDL Panel - This test looks at the amount of oxidised or rancid cholesterol in the blood. This should be within normal limits of the test. It is available through LabCorp.


The Cardio IQ Test - uses a different technology and is available from Quest Diagnostics. This test goes far beyond simple LDL, HDL and Triglyceride testing. Quest Diagnostics offers advanced cardiovascular tests that help provide a more accurate and individualised assessment of risk. The tests look beyond just HDL and LDL cholesterol to identify undiagnosed (or additional) risk. These advanced cardiovascular tests, along with a lipid panel, will provide more information that can be used to determine the complete cardiovascular profile.  Cardio IQ Ion Mobility tests directly detects, measures and quantifies the number and size of all lipoprotein sub fractions.  Knowing what particles make up the LDL and HDL cholesterol may be important. Ion Mobility Technology provides subclass separation that will allow to identify cardiovascular risk over time. Following the change in the lipid profile as a patient responds to diet, exercise and possible medication to reduce cardiovascular risk is important.   Ion Mobility provides the opportunity to determine whether treatment is working and if not, optimize the intensity of therapy to hopefully make a difference that can be seen in the Ion Mobility measurement and graphical representation of the LDL and HDL particles.  It is important to track this as changes to diet are made. These are really the only cholesterol tests you should have.


Apolipoprotein B (apoB) - In Europe and other parts of the world where NMR and Cardio IQ Ion Mobility tests are not available, LDL particle number is more commonly measured using an indirect marker, apolipoprotein B (apoB). ApoB is a protein required for the formation of the LDL particle. About 90-95% of apoB particles are LDL particles, which makes apoB a fairly accurate measure of LDL particle number. If you live in a country where the NMR profile is not available, you can use the apoB test to roughly determine your LDL particle number, and then use triglycerides, HDL, fasting blood sugar, blood pressure and waist-to-hip ratio to determine if you have insulin resistance.



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