Month: November 2018

In the previous article titled When Normal Fasting Blood Glucose Results Aren’t Necessarily “Fine” I explained how normal results on a fasting blood glucose (FBG) test may simply mask ‘silent Diabetes’ and that even when fasting blood glucose is normal and results from a 2-hour Oral Glucose Tolerance Test (2-hr OGTT) do not indicate glucose intolerance, a person can still have a very abnormal blood sugar response after they eat refined carbohydrates. These spikes’ can be seen between 30 minutes and 60 minutes on 2-hour glucose curves and are reflected by equally abnormal insulin curves. Chronically high circulating levels of insulin (called hyperinsulinemia) result from these blood sugar ‘spikes’ that occur every time the person eats carbohydrate-based foods, which is usually every few hours, for meals and snacks.

Insulin is released in order to take the excess sugar resulting from the digestion of carbs and move it out of the blood and into the cells and even though these people’s blood glucose returns to below the impaired glucose tolerance range by 2 hours, the abnormal glucose response particularly between 30 and 60 minutes drives hyperinsulinemia (chronically high levels of insulin) and is made worse by insulin resistance (which is the ignoring of insulin’s signal by the cells).  It is this hyperinsulinemia and insulin resistance that are the essence of carbohydrate intolerance; ; the varying degrees to which people can tolerate carbohydrate without their blood sugar spiking. It is not unlike other food intolerances such lactose intolerance or gluten intolerance which also reflect the body’s inability to handle specific types of carbohydrate in large quantities.

It is the hyperinsulinemia, rather than the high levels of blood sugar that puts people at risk for the serious chronic diseases of cardiovascular disease (heart attack and stroke), high cholesterol and high blood pressure[1] that people usually associate with type 2 diabetes. High blood sugar does have risks of course, including loss of vision, chronic kidney disease and amputation of limbs but if high blood sugar (hyperglycemia) is the “tip of the iceberg”, then high circulating levels of insulin (hyperinsulinemia) is the bigger part of the iceberg that can’t be seen. We can’t see it simply because it is rarely, if ever measured.

Most concerning is that based on a large-scale 2016 study which looked at the blood glucose response and circulating insulin responses from almost 4000 men aged 20 years and older and 3800 women aged 45 years or older during a 5-hour Oral Glucose Tolerance Test, 53% had normal glucose tolerance (normal fasting blood sugar and did not have impaired glucose tolerance (IGT) at 2 hours after the glucose load) but of these people, 75% had abnormal blood sugar results between 30 minutes and 60 minutes (two points in time that are not normally looked at in a standard 2-hour Oral Glucose Tolerance Test (2-hr OGTT).

A normal blood glucose curve represents Carbohydrate Tolerance, and there are 3 Stages of Carbohydrate Intolerance — early, advanced, and severe, with the final stage being a diagnosis of type 2 diabetes (T2D).

Hyperinsulinemia combined with insulin resistance form the heart of Carbohydrate Intolerance.

Insulin Resistance

In the early stages of Carbohydrate Intolerance, receptors in the liver and muscle cells begin to stop responding properly to insulin’s signal. This is called insulin resistance. Insulin resistance can be compared to someone hearing a noise such as their neighbour playing music, but after a while their brain ”tunes out” the noise.  Even if the neighbour gradually turns up the volume of the music, the person’s brain compensates by further tuning out the increased noise. This is what happens with the body when it becomes insulin resistant. It no longer responds to insulin’s signal. To compensate for insulin resistance, the β-cells of the pancreas begin producing and releasing more and more insulin resulting in hyperinsulinemia, which is too much insulin in the blood.

Normal Insulin Response

The β-cells of the pancreas of healthy people are constantly making insulin and storing most of it until these cells receive the signal that food containing carbohydrate has been eaten. β-cells also constantly release small amounts of insulin in very small pulses called basal insulin. This basal insulin allows the body to use blood sugar for energy even when the person hasn’t eaten for several hours or longer. The remainder of the insulin stored in the β-cells is only released when blood sugar rises after the person eats foods containing carbohydrate and this insulin is released in two phases; the first-phase insulin response occurs as soon as the person begins to eat and peaks within 30 minutes and can be seen at 30 minutes on the graph below. The amount of the first-phase insulin release is based on how much insulin the body is used to needing each time the person eats. Provided a carbohydrate tolerant person eats approximately the same amount of carbohydrate-based food at each meal day to day, the amount of insulin in the first-phase insulin response will be enough to move the excess glucose from the food into the cells, returning blood sugar to its normal range of ~100 mg/dl (5.5 mmol/L). If there is not enough insulin in the first-phase insulin response, the β-cells will release a smaller amount of insulin within an hour to an hour and a half after the person began to eat.

Below is the Carbohydrate Tolerance curve (i.e. normal glucose curve). The solid black line is unlabeled and is shown along with its corresponding normal insulin curve (dashed line). The insulin response more or less mirrors the glucose response; as glucose rises in the blood, insulin is released mainly as a first-phase insulin response, which results in the blood glucose level falling.

In 990 people with normal glucose tolerance and normal insulin tolerance (i.e. with curves like the one above), mean fasting insulin = 48.6 pmol/L, which is equivalent to 7 uU/ml / 7 mU/L [SD = 5 mU/L]. Therefore the normal range for fasting insulin 2-12 uU/ml.

Early Carbohydrate Intolerance

Below is the Early Carbohydrate Intolerance curve and the solid black line (glucose) is shown along with its corresponding abnormal insulin curve (dashed line). As glucose rises in the blood even more insulin is released; initially as a first-phase insulin release and then as a second-phase insulin release.  This results in blood glucose level falling but not to baseline (fasting level) by 2 hours afterwards. Notice too that the fall is not as a straight line, but there are two peaks in the glucose curve, before it falls.

It is insulin resistance of the liver and muscle cells which results in the β-cells of the pancreas making more insulin and as can be seen from the graph below it takes more insulin to move the same amount of glucose (carbohydrate) into the cell.

Advanced Carbohydrate Intolerance

By the time people have progressed to Advanced Carbohydrate Intolerance, the first-phase insulin response won’t produce enough insulin be able to clear the extra blood glucose after a carbohydrate load and even the second-phase insulin response won’t be enough to overcome the insulin resistance of the cells. At this point, the β-cells of the pancreas are unable to make enough insulin to clear the excess glucose from the blood and blood glucose rises well above the normal high peak of 126 mg/dl (7.0 mmol/L).  What is also apparent is that even with all the insulin release, blood sugar levels begin rising sooner and rise to much higher levels.

With ongoing high intake of carbohydrate every few hours, especially refined and processed carbohydrate such as bread, pasta and rice which are broken down quickly to glucose, the amount of insulin that must be released from the β-cells of the pancreas to handle a steady intake of carbohydrate-based foods increases substantially.  The dashed black line on the graph below shows the insulin curve of Advanced Carbohydrate Intolerance. While the Early Carbohydrate Intolerance glucose curve (above) doesn’t look significantly different then the Advanced Carbohydrate Intolerance curve (below), it’s easy to see that the insulin curves are very different.

The hyperinsulinemia (high levels of circulating insulin) present in Advanced Carbohydrate Intolerance is what makes these two states different.

Most concerning is these people had normal fasting blood sugar and 2-hour postprandial blood sugar which did not indicate that they had impaired glucose tolerance.  On a 2-hr OGTT, these folks would be told they were not pre-diabetic and would assume that everything was find — yet they had both an abnormal glucose response between 30 minutes and 60 minutes and abnormally high levels of insulin which accompanies it.

This high insulin response occurs every time these people eat significant amounts of refined carbohydrate and puts them at increased risk of the chronic diseases associated with chronic hyperinsulinemia including heart attack and stroke, hypertension (high blood pressure), elevated cholesterol and triglycerides, non-alcoholic fatty liver (NAFLD), Poly Cystic Ovarian Syndrome (PCOS), Alzheimer’s disease and other forms of dementia, as well as certain forms of cancer including breast and colon cancer [1].

A standard 2-hour OGTT would not show the significant abnormality in terms of how the body is able (or rather, not able) to process carbohydrate because standard blood tests do not test either glucose or insulin at 30 and 60 minutes.  It’s not that there aren’t abnormalities, it is just that they are not measured!

 Severe Carbohydrate Intolerance

As Carbohydrate Intolerance progresses, some people’s glucose-insulin curves look like the ones below. Blood sugar levels don’t rise as high, but the β-cells of the pancreas are producing less insulin and releasing it much later. They have no idea, because their fasting blood sugar is still normal.

Type 2 Diabetes

Type 2 Diabetes (T2D) is the final stage of Carbohydrate Intolerance and is the natural outcome of a person continuing to eat a diet high in carbohydrate-containing foods when their body is unable to tolerate it. Too often this is the natural outcome of people following Dietary Guidelines (US or Canadian) which are designed for a healthy population, not people who are metabolically unwell. The problem is most people think they are healthy because they have normal blood glucose tests, and their metabolic dysfunction is never diagnosed. No one is looking for it.

The Dietary Guidelines recommend that people eat 45-65% of their dietary intake as carbohydrate and people in both countries dutifully eat considerable amounts of carbohydrate in the form of bread, cereal, rice and pasta, as well as fruit, milk and sweetened yogurt and starchy vegetables such as peas, corn and potato. Not knowing their body has become carbohydrate intolerant, this chronically high intake of carbs continues to put strain on their pancreas, until udder the pressure of the combination of hyperinsulinemia and insulin resistance, their β-cells burn out, resulting in Type 2 Diabetes.

Some Final Thoughts…

It has been said that type 2 diabetes is a ”chronic, progressive disease”, but does it doesn’t have to be this way! It can be stopped LONG before fasting blood sugars become abnormal.

Diagnosing hyperinsulinemia is simple and can be done with existing standard lab tests; namely a 2-hour Oral Glucose Tolerance test with an extra glucose assessor and extra insulin assessor at 30 minutes and 60 minutes. When patients request this test because they are at high risk, too many are told that it is “a waste of healthcare dollars” when quite literally they could be spared the scourge of type 2 diabetes by having the changes in insulin and glucose response diagnosed in the 20 years before standard blood sugar begins show abnormalities [2].

NOTE (March 9, 2021): Some family medicine doctors won’t order tests to assess insulin along with glucose in order to “save healthcare system dollars” — but instead will send their patient to an endocrinologist which costs the system ~$300 before any tests are run. Why? In parts of Canada, if audited, family medicine physicians have to re-pay for preventative tests (which are deemed “unnecessary”) . Self-paying for these tests is an option to consider.

It’s time to think about ways to implement dietary changes and lab testing procedures that will prevent Carbohydrate Intolerance and from developing the abnormal glucose and insulin responses and the host of metabolic diseases that go along with them.

In fact, it is long overdue.

If you would like my help in lowering your risk to developing type 2 diabetes and the chronic disease risks associated with hyperinsulinemia, or reversing their symptoms, then please send me a note using the Contact Me form, on the tab above.

To your good health!

Joy

You can follow me at:

https://twitter.com/lchfRD

https://www.facebook.com/BetterByDesignNutrition/

 

References

1. Crofts, C., et al., Identifying hyperinsulinaemia in the absence of impaired glucose tolerance: An examination of the Kraft database. Diabetes Res Clin Pract, 2016. 118: p. 50-7.
2. Sagesaka H, S.Y., Someya Y, et al, Type 2 Diabetes: When Does It Start? Journal of the Endocrine Society, 2018. 2(5): p. 476-484.

---

Copyright ©2018 BetterByDesign Nutrition Ltd.

LEGAL NOTICE: The contents of this blog, including text, images and cited statistics as well as all other material contained here (the ”content”) are for information purposes only.  The content is not intended to be a substitute for professional advice, medical diagnosis and/or treatment and is not suitable for self-administration without the knowledge of your physician and regular monitoring by your physician. Do not disregard medical advice and always consult your physician with any questions you may have regarding a medical condition or before implementing anything  you have read or heard in our content.

 

INTRODUCTION: When people have a fasting blood glucose test and the results come back normal they’re told (or assume) that everything’s fine. But is it? Certainly, a fasting blood glucose test is the least expensive test to find out if someone is already pre-diabetic, but for those wanting to avoid becoming diabetic and to lower their risk of the other chronic disease associated with type 2 diabetes and high levels of circulating insulin (called hyperinsulinemia) noticing abnormalities in how we process carbohydrates is essential and these changes are estimated to take place a decade before our fasting blood sugar begins to become abnormal.

---

Our bodies have to maintain the glucose (sugar) in our blood at or below 5.5 mmol/L (100 mg/dl) but each time we eat or drink something other than water or clear tea or coffee, our blood sugar rises as our body breaks down the carbohydrate in the food from starch and complex sugars to glucose, a simple sugar.  Eating causes hormones in our gut, called incretin hormones to send a signal to our pancreas to release insulin, which moves the excess glucose out of our blood and into our cells. When everything is working properly, our blood sugar falls back down to a normal level within 2 hours after we eat.

If we’re healthy and don’t snack after supper, our blood sugar falls to a lower level overnight but that too is maintained in a tightly regulated range between 3.3 mmol/l (60 mg/dl) and 5.5 mmol/l (100 mg/dl). During the night and as we approach morning, our body will break down our stored fat for energy and convert it to glucose in a process called gluconeogenesis.

When we have a fasting blood glucose test, it measures our blood sugar after we’ve fasted overnight and when we’re healthy, the results will be between 3.3-5.5 mmol/L (60-100 mg/dl). If it is higher than 5.5 mmol/l (100 mg/dl) but less than 6.9 mmol/L (125 mg/dl) we are diagnosed with impaired fasting glucose, but what if it’s normal? Is a normal fasting blood glucose test result enough to say that we’re not at risk for Type 2 Diabetes? No, because a fasting blood glucose doesn’t tell us anything about how our body responds when we eat!

A 2 hour Oral Glucose Tolerance Test (2 hr-OGTT) may be requested for people whose fasting blood glucose is impaired (higher than 5.5 mmol/L) in order to see if it returns to normal after they consume a specific amount of glucose (sugar).

If their blood sugar returns to normal (less than 5.5 mmol/L) 2 hours after drinking a beverage containing 75 g of glucose (100 g if they’re pregnant) then the diagnoses remains impaired fasting glucose because it is only abnormal when fasting. However, if the results are greater than 7.8 mmol/L (140 mg/dl) but below 11.0 mmol/L (200 mg/dl), then they are diagnosed with impaired glucose tolerance which is called “pre-diabetes”.

If the 2 hour results are greater than 11.0 mmol/L (200 mg/dl), then a diagnosis of Type 2 Diabetes is made because their fasting blood glucose is > 7.0 mmol/L (126 mg/dl) and their 2 hour blood glucose is > 11.0 mmol/L (200 mg/dl).

But what if someone’s fasting blood glucose is normal? Does this mean that everything’s fine? Not necessarily, unless we know what happens to their blood sugar after a carbohydrate load, especially after 30 minutes or 60 minutes.

A 2016 study looking at blood sugar response (and insulin response) from almost 4000 men aged 20 years or older and 3800 women aged 45 years or older who had a 5 hour Oral Glucose Tolerance Test using 100 g of glucose. The study found that 53% had normal glucose tolerance; that is, they had normal fasting blood sugar and did not have impaired glucose tolerance (IGT) 2 hours after the glucose load. Of these people with normal glucose tolerance, 75% had abnormal blood sugar results between 30 minutes and 1 hour.

Normal Blood Glucose Pattern

Based on the above study, a little less than 1000 people (990) out of the total with normal glucose tolerance (4030) had a normal glucose pattern after having 100 g of glucose (see graph below). See how the blood sugar rises to a moderate peak and then decreases steadily until it’s back to where it started from at 2 hours. This is what blood sugar is supposed to do.

Abnormal Glucose Patterns

Almost the same number of people (961) as had normal glucose curves showed early signs of carbohydrate intolerance which can be seen most noticeably between 30 and 60 minutes. These folks had normal fasting blood glucose and but after 2 hours, blood glucose did not return to baseline, but did not meet the criteria for impaired glucose tolerance. Unless someone was looking between 30 and 60 minutes, one would not know it was not normal in between. Keep in mind, this graph represents the average blood sugar response of these individuals. Rather than blood glucose going up to a moderate peak and then falling gradually, a two-stage rise in glucose can be clearly seen between 30 minutes and 60 minutes before beginning to drop. These people had normal fasting blood sugar and while their blood sugar at 2 hours was below the cutoff for impaired glucose tolerance, it was higher than at baseline.

A little more than 1200 people (1208) had the follow abnormal glucose response between 30 and 60 minutes where blood sugar actually went slightly higher at 60 minutes than at 30 minutes before beginning to fall. While these people had normal fasting blood glucose their blood glucose did not fall to baseline at 2 hours but was below the cutoffs for impaired glucose tolerance.

Slightly more than 800 people (807) had an abnormal glucose response curve shaped as follows, with normal fasting blood glucose and  2-hour postprandial blood glucose results that were higher than at baseline, but did not meet the criteria for impaired glucose tolerance. What was significant is that blood sugar was significantly higher at 60 minutes than at 30 minutes.

The Significance of These Curves

The results of this study shows that even if fasting blood glucose is totally normal AND 2 hour postprandial blood glucose does not meet the criteria for impaired glucose tolerance, it often does not return to baseline and  the blood sugar response between fasting and 2 hours is very abnormal. What can’t be seen from these graphs is what happens to the hormone insulin at the same time. This will be covered in a future article, but suffice to say that in the normal glucose response pattern, blood sugar response mirrors what is happening with insulin but in the abnormal blood glucose response insulin secretion is both much higher and lasts much longer. This is called hyperinsulinemia (high blood insulin) and contributes to many of the same health risks as Type 2 Diabetes, including cardiovascular risks (heart attack and stroke), abnormal cholesterol levels and hypertension (high blood pressure).  This is like having “silent Diabetes”.

A “Waste of Healthcare Dollars”

When a person’s clinical symptoms and risk factors warrant it, I’ll request a 2 hour Oral Glucose Tolerance Test with an extra assessor at 30 minutes (and sometimes at 60 minutes) to determine how their glucose response compares to the above curves. Since these people have normal fasting blood glucose test results, a request for an Oral Glucose Tolerance Test (with or without the extra glucose assessor) is often declined as a “waste of healthcare dollars”.

What About Glycated Hemoglobin (HbA1C)?

A glycated hemoglobin test (HbA1C) measures a form of hemoglobin that binds glucose (the sugar in the blood) and is used to identify the person’s three-month average glucose concentration because blood cells turnover (get replaced) on average every 3 months.

While having a glycated hemoglobin test and a fasting blood glucose test is better than only having fasting blood glucose, it will still miss a significant percentage of people who are able to control their sugars between meals and overnight but who have significant spikes after eating food, between 30 minutes and 60 minutes, but that return to normal by 2 hours. Since most physicians will not even requisition a HbA1C test if a person’s fasting blood glucose is normal, and even if they do that test can miss the glucose spoke that occurs between 30 minutes and 60 minutes after eating, this is the reason I sometimes resort to using a Glucose Response Simulation.

Glucose Response Simulation

A simple, if somewhat crude means of assessing glucose response under a load can be done at home using an ordinary glucometer (a meter for measuring blood sugar) such as would be used by people with Diabetes, and either a 100 g of dextrose (glucose) tablets (available at most pharmacies) or the equivalent. As part of the services I provide to my clients, I work with those that want to do this type of estimate so that they can understand whether they fall into the 75% of people that have normal fasting blood sugar and do not have impaired glucose tolerance at 2 hour postprandial, but do have an abnormal glucose response, as well as hyperinsulinemia. I explain how to prepare for the test, step by step instruction for conducting the test and then I graph and analyze the data then teach them what the results mean.

Basis for Individualizing Carbohydrate Intake

These results are very helpful as firstly they help people understand the reason for reducing their carbohydrate intake over an extended period of time, in order to restore insulin sensitivity and insulin secretion. These results also enable me in time to individualize their carbohydrate intake once they have reversed some of their metabolic response, based on their own blood sugar response to a specific carbohydrate load.  In time, some of these individuals may want to add some carbohydrate back into their diet in small quantities, so with this information, I can guide them to test a standard size serving of rice, pasta or potato compared to their own blood glucose response to 100 g of glucose.

Below are three curves that I’ve plotted from people that all used the same type of glucometer (Contour Next One) which was rated as the best in a 2017 survey (see earlier post) and a standard 100 g glucose load as dextrose tablets or equivalent to 100 g of glucose [2]. I provided each one with identical instructions on how to run this simulation and to collect the results and ensured they understood.

Example 1: The person below had a single glucose peak (similar to the early carbohydrate intolerance of the first abnormal curve, above) but blood glucose did not come back down to the fasting level even after 3 hours.

Example 2: The person below had a single glucose peak  that reached abnormally high levels and that didn’t fall continuously downward but slowed, then dipped below baseline at 2 hours and that gradually came back to baseline over the following couple of hours.

Example 3: This person had a similar initial rise as the person above, but no dip below baseline. In fact, this person’s glucose didn’t fall to baseline until almost 5 hours.

Some Final Thoughts…

An abnormal fasting blood glucose test may warrant further testing, however a normal result is frequently dismissed as being a sign that “everything’s fine”. Data from this study indicates that as many as 75% of people with normal fasting blood sugar may have abnormal glucose responses and associated hyperinsulimia and some of the same risks as someone who has already been diagnosed with Type 2 Diabetes, but they simply don’t know it.

With reliable and relatively inexpensive glucometers, as well as continuous glucose monitors (CGM) people don’t need to wonder whether they are in the minority with a normal glucose response.

Not knowing one is at risk does nothing to provide motivation to make dietary and lifestyle changes, but knowing one has an abnormal response to carbohydrate not only enables them to want to make changes, it enables them  to find out in time which carbohydrates might be able to be added back into their diet, and in what quantities.

If you have questions as to how I can help you get started in knowing your own glucose response and to lower risk factors, please send me a note using the Contact Me form located on the tab, above.

To your good health!

Joy

References

1. Crofts, C., et al., Identifying hyperinsulinaemia in the absence of impaired glucose tolerance: An examination of the Kraft database. Diabetes Res Clin Pract, 2016. 118: p. 50-7.
2. Lamar, ME et al, Jelly beans as an alternative to a fifty-gram glucose beverage for gestational diabetes screening, Am J Obstet Gynacol, 1999 Nov 18 (5 Pt 1): 1154-7

You can follow me at:

 https://twitter.com/lchfRD

  https://www.facebook.com/BetterByDesignNutrition/

---

Copyright ©2018 BetterByDesign Nutrition Ltd.

LEGAL NOTICE: The contents of this blog, including text, images and cited statistics as well as all other material contained here (the ”content”) are for information purposes only.  The content is not intended to be a substitute for professional advice, medical diagnosis and/or treatment and is not suitable for self-administration without the knowledge of your physician and regular monitoring by your physician. Do not disregard medical advice and always consult your physician with any questions you may have regarding a medical condition or before implementing anything  you have read or heard in our content.