Blood Sugar 101: What They Don’t Tell You About Diabetes
By
Jenny Ruhl
Published by Technion Books at Smashwords
Copyright 2011 Janet Ruhl. All rights reserved.
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Introduction
Type 2 Diabetes is a terrible disease. It causes impotence, blindness, kidney failure, amputation, and heart attack death.
But Type 2 Diabetes is also a wonderful disease because all these dreadful outcomes are optional. No matter how severe your diabetes might be at diagnosis, it is unique among the serious chronic diseases in that it is the only condition where you, the patient, with only a small amount of help from your doctor and no heroic medical interventions can achieve normal health.
This is probably not what you have heard from your doctors. They probably told you it is normal for someone with diabetes to suffer foot pain, impotence, slow wound healing, low physical energy, and even a heart attack. So why should you believe me when I tell you it isn’t true?
For a very good reason: Over the past decade diabetes treatment has been revolutionized by the emergence of what is often called “The Wisdom of the Web.” This term refers to the phenomenon where many thousands of people, each drawing on their own knowledge and experience, create information resources as good or better than those produced by so-called authorities.
Diabetes on the Web
Diabetes was one of the first diseases to benefit from the Wisdom of the Web because people with diabetes have always been expected to do most of the work involved in managing their disease. They’ve tested their own blood sugar. They’ve adjusted their own insulin doses.
So even before the advent of the Web they had a lot of information about how their blood sugar responded to changes in their diet, medications, and exercise. What they didn’t have was any idea of how their own experience might compare with that of others.
With the emergence of the Web, people with diabetes began to talk to each other on newsgroups and discussion forums, they exchanged information they’d gotten from their solitary testing, they started comparing notes. When they did this, they soon discovered that they weren’t the only ones who were having problems with the diets and drug regimens prescribed by doctors and dietitians.
Some people who were active on the Web started trying out alternative diets and drug regimens and reporting their results to each other in the discussion groups. Others started combing through the thousands of peer-reviewed journal articles that had been made available for free on the Web, searching for studies that might point to more effective diabetes treatments. Over time, the information they found and shared started making big improvements in their health.
The 5% Club
Since my own diabetes diagnosis in 1998 I have participated in thousands of Web discussions with hundreds of people with diabetes.
Many of them had science or engineering backgrounds like my own. [NOTE: I’m a software developer.] This gave them a penchant for critical thinking and the skills needed to read and understand journal research. Working together, we learned that it is possible for people with diabetes to achieve normal blood sugars. We also uncovered research that suggests that if we maintain truly normal blood sugars we will avoid or even reverse the terrible complications our doctors told us were inevitable.
Some of us call ourselves “The 5% Club” because our goal is to keep our A1c test results under 6%. That is the level most doctors consider to be the normal range. Using a selection of techniques I’ve learned from participating in Web discussion groups, I’ve managed to stay in The 5% Club for almost all of the ten years that have followed my diagnosis. Though it has been that long since I was diagnosed, my endocrinologist still refers to me as “recently diagnosed” because she is used to seeing A1cs that low only in people who are new to diabetes.
Why This Book?
Five years ago, after realizing that many people were unaware of the wealth of information to be found in Web discussion groups, I decided to put the most important information on a Web site where people doing Google searches could easily find it. The heart of my Web site was what I learned after spending several months reading through medical journals, hunting for studies that answered two questions: “What is a truly normal blood sugar level?” and “What blood sugar levels cause organ damage?” The result was my Web site Bloodsugar101.com.
This site is different from most other diabetes Web sites because the information you find on it includes links to studies published in top-rated peer-reviewed medical journals. Visitors to the site don’t have to take anything on trust. They can follow the links and read the research papers themselves. My Web site is also updated any time something significant turns up in the medical news that is relevant to a topic discussed on its pages.
Over the five years of its existence, the site has grown huge. Visitors started asking me if I could put the mass of information stored on the Web site into book form so they could read it more easily. They explained that because the site has grown so large, they could not read the whole thing on the Web and worried that they might be missing out on critical pieces of information buried in its pages.
Since I had already published seven previous books of nonfiction, including a business bestseller, I was excited by the challenge of turning the site into a book. My enthusiasm for the project grew when I began to write it, as I began to see another advantage to putting what I’d written about diabetes into book form: A book is better than a Web site at explaining ideas that can’t be compressed into a few simple paragraphs, because the sequential structure of a book ensures that every concept you encounter in its pages builds on what you have already read. A book is also free of the distractions inherent in the Web’s hypertextual design.
So I hope that this book will add value to the Web site by providing, in a compact and portable form, an orderly examination of the crucial concepts that pervade it. In its pages you will find the explanations that will make you understand, as you never have before, how your blood sugar works, what happens when your blood sugar control breaks down, what blood sugar levels damage your organs, and how you can safely lower your blood sugar enough to prevent any further diabetic complications from occurring.
Every concept presented in the text is backed up by peer-reviewed research papers that were published in highly regarded medical journals. If you want check out this research, you can find the citations in the “References” section at the end of this book. You can find links to these studies and the lastest new findings on Bloodsugar101.com.
There are some very important issues that people with diabetes must deal with that are not discussed in peer-reviewed research. Here the Wisdom of the Web comes into play, and I draw on the experiences reported by the hundreds of knowledgeable people with diabetes who post messages on the Web. When I cite this type of information, I make it clear that anecdotal reports are its source.
No One Way
Unlike most other diabetes books on the market, this book does not tell you what to eat or what medications to take. If there is one thing we have learned from the Wisdom of the Web, it is that each of us is different and that a strategy that works well for one person may not work for another.
Instead we will teach you how to tell if any diabetes strategy you are using is working. By “working” we mean giving you blood sugars low enough to prevent any further organ damage. We’ll show you how to find out if your current diabetes diet is doing the job and, if it isn’t, we’ll show you how to improve it. If you need more than a change of diet to get your blood sugars back into the safe zone, we’ll explore what the diabetes drugs available to you are good for and what their drawbacks are, putting particular emphasis on some cheap but effective diabetes drugs that doctors may overlook because they aren’t being promoted by drug company marketing campaigns.
What’s in it for You?
When you are done reading this book, you will know enough to hold an intelligent conversation with your doctor about your treatment choices. You’ll be better able to evaluate the latest “breakthroughs” you read about in the diabetes news. And most importantly, you’ll have the information you need to keep yourself safe, no matter what current fad is sweeping the medical community. In short, when you are done with this book, you will have the tools you will need to join “The 5% Club” yourself. So welcome aboard!
Chapter One: What is Normal Blood Sugar?
Diabetes is not a disease, it is a symptom.
Everyone diagnosed with any type of diabetes shares a single symptom with every other person with diabetes. That symptom is high blood sugar.
Anything that interferes with the complex mechanisms that the body uses to regulate blood sugar may cause diabetes. It may occur when the cells that secrete insulin get poisoned or die off or when those cells fail to respond to the signals that tell them to make insulin.
It may even occur when those cells are making plenty of insulin but insulin receptors in the cells have lost their ability to respond to it.
Diabetes can be caused by abnormalities of the adrenal glands or problems with hormones in the gut that inform the body of the presence of food.
It is also possible for one person to have more than one of these metabolic problems at the same time. For example, the most common form of diabetes, which doctors call Type 2 Diabetes, is frequently described as being caused by insulin resistance, the condition where cell receptors stop responding properly to insulin. But scientists have recently discovered that almost one in twelve of those diagnosed with insulin resistant Type 2 Diabetes also have markers in their bloodstream that show they have been the victim of an autoimmune attack that has killed off the cells that make insulin.
What does this mean for you?
Simply this: Though you may have been diagnosed with diabetes, all that your diabetes, my diabetes, and the diabetes of the person sitting across from you at the diabetes support group meeting have in common is that they cause all of us to have abnormally high blood sugars. The cause of our high blood sugars may be different, how high our blood sugars rise after we eat the identical meal may be different, how our bodies respond to the same dose of the same drug may be dramatically different, and, most importantly, what it takes to bring our blood sugars back into the normal range that prevents complications will be different.
Because we are all so different, the key to recovering good health is to figure out how your own individual version of diabetes works.
The first step towards doing this is to learn how blood sugar is regulated in a normal person and how normal blood sugar control breaks down. Armed with this information you will be better able to understand what the various interventions used to treat diabetes do—and which ones might be right for you. So take the time to understand the information you’ll find in the next couple pages. It will give you the background you need to take control of your health.
Blood Sugar Control in Normal People
Most of your cells can run on several different kinds of fuel. One of them is a sugar called glucose. It is the sugar we refer to as blood sugar. Some glucose always circulates in the bloodstream, where it can be available to any cell that might need it. When you read that your blood sugar is 100 mg/dl, what this is really telling you is that there are 100 milligrams of glucose—one tenth of a gram, in every deciliter of your blood. A deciliter is one tenth of a liter. So if your blood sugar is 100 mg/dl you have 1 gram of glucose in every liter of blood. [NOTE: All blood sugar meter readings discussed in this book are given as plasma calibrated values. Though all meters test only whole blood, plasma calibrated meters adjust the reading to match the value you'd get if you had your blood plasma tested at a lab. All meters currently sold in the U.S. use this kind of calibration. But some older meters and some meters sold in the UK are still whole blood calibrated. To convert a whole blood calibrated reading to a plasma calibrated reading, multiply it by 1.12. To convert the blood sugar measurements used here to whole blood calibrated values, divide by 1.12.] Everywhere except in the U.S., blood sugar is measured using a different measurement of concentration: mmol/L which stands for millimoles per liter. To convert mg/dl into mmol/L you divide mg/dl by 18.05. In Appendix A you will find a table you can use to find the mmol/L equivalent of any blood sugar mentioned in these pages.
Before most cells can use glucose, it must be transported inside the cells. Insulin is the hormone that makes this happen. That is why insulin is so important to blood sugar control. If there is no insulin available, no matter how much glucose is circulating in your bloodstream most of your cells will not be able to use it. And if the sugar in your blood isn’t taken into cells, it will build up to dangerously high levels which will damage your organs and can even lead to death.
Insulin is produced by special cells called beta cells. These tiny cells are found in structures called the Islets of Langerhans which are scattered throughout your pancreas. The pancreas is an organ located near your liver that also secretes digestive enzymes. The job of the beta cell is to manufacture insulin, store it, and release it into the bloodstream when appropriate. Healthy beta cells are continually making insulin and storing it within the beta cell in the form of tiny granules.
The beta cells release this insulin into the bloodstream in two different ways. They release a continuous trickle of what is called Basal Insulin throughout the day and they also release larger bursts of insulin after you eat a meal. The meal time releases are called First- and Second-Phase Insulin Release.
Basal Insulin Release
The purpose of basal insulin release is to keep a small amount of insulin available in the bloodstream at all times. The beta cells of a healthy person release a small amount of insulin into the bloodstream in small pulses that occur every few minutes throughout the day and night. Maintaining this steady supply of insulin is important. It allows the cells of the body to utilize blood sugar whenever they need it.
During periods between meals the healthy beta cell also manufactures extra insulin and stores it in the form of granules for use at meal time. One of the things scientists have learned recently is that diabetes may develop when something disrupts the timing of this pulsed basal insulin release. Problems with basal insulin production can also keep the beta cells from storing the granules of insulin that will be used at meal times.
When you test your fasting blood sugar after not eating for eight hours or more, you are examining the health of your ability to secrete basal insulin. A normal or near normal fasting blood sugar means that your ability to secrete basal insulin is still intact. Truly normal fasting blood sugar values fall in the range between 70 and 85 mg/dl. Doctors will tell you that the normal range for a fasting blood sugar extends up to 100 mg/dl, but quite a lot of research has shown that people whose fasting blood sugar is over 90 mg/dl are very likely to develop diabetes within a decade, which suggests that it is not truly normal.
Insulin Levels Signal the Liver Whether More Glucose is Needed
The liver is the organ whose job is to add glucose to the blood stream if the blood sugar level starts to drop too low. If basal insulin production is working properly, the steady level of insulin in the bloodstream sends the signal to the liver that all is well and that no more glucose is needed. But if the insulin level drops during a fasting period, or if the liver becomes insulin resistant and does not respond to insulin signaling, the liver will assume that the glucose in the bloodstream is getting used up and more glucose is needed.
When the liver gets the signal that more glucose is needed, it turns to some carbohydrate it has stored for just this purpose. The term carbohydrate refers to the nutrients we call sugars and starches. The liver stores carbohydrate in the form of a substance called glycogen.
To raise the blood sugar, the liver converts this glycogen into glucose and then dumps the resulting glucose into the bloodstream. This raises the blood sugar back to its normal level and ensures that cells will continue to have the fuel they need.
If it doesn’t have enough glycogen stored, the liver can convert protein into glucose, too, and it will do this using protein from the food you have recently eaten. If you aren’t eating enough protein, the body will break down the protein stored in your muscles, to provide the glucose the body needs. [NOTE: This ability of the liver to turn muscle into glucose is why dieters lose muscle mass if they don’t get enough protein when they are on stringent diets]
First-Phase Insulin Release
s soon as a healthy person starts to eat a meal, the parasympathetic nervous system sends out signals that begin the process that causes beta cells to release insulin into the bloodstream, beginning with the insulin they previously stored in granules.
As soon as the food hits the stomach, the carbohydrates in that food start to digest. Any pure glucose you have eaten goes immediately into the blood stream as it doesn’t need to be broken down any further. Fructose gets whisked away to your liver which converts it into fat. Digestive enzymes break down the rest of the carbohydrates in your meal into the two simple sugars, glucose and fructose, and that glucose goes into your bloodstream, too. It takes no more than 15 minutes after you have eaten a meal containing sugar or starch for the first glucose from the digested food to reach the bloodstream and begin raising the concentration of glucose in your blood.
Rising blood sugars now stimulate the beta cells to secrete more insulin. At the same time, as blood sugars rise to a threshold—somewhere between 100 and 120 mg/dl—incretin hormones released by the gut also stimulate the beta cells to secrete insulin. These early releases of insulin that occur as soon as you begin eating a meal are called first-phase insulin release. In a healthy person first-phase insulin release keeps the blood sugar from rising much over 125 mg/dl.
What cells take up that glucose? The brain and muscles have first dibs. Then the liver will use some glucose to top off its store of glycogen. But if your brain and muscle cells are all set for glucose and your liver has enough glycogen, insulin pushes glucose into fat cells.
Insulin plays an important part in the process that transforms glucose into fat.
The amount of insulin a normal person’s beta cells secrete during this first-phase insulin release is believed to be very close to the amount they needed to process the glucose produced by previous meals. If they usually eat a lot of carbohydrate, their body will release more insulin at the start of the next meal, even if that meal doesn’t contain much carbohydrate. If this large dose of first-phase insulin doesn’t meet up with enough incoming carbohydrate, it may drive the normal person’s blood sugar low. When blood sugar drops too low, the brain senses it and sends out hunger signals that ramp up carbohydrate cravings. This is suggested as a reason why people with normal or near-normal metabolisms who have been eating a lot of carbohydrate may find themselves craving carbohydrates if they try to cut down on their carbohydrate intake.
If the normal person doesn’t respond to the low blood sugar attack by eating more carbohydrate, their liver will transform stored glycogen into glucose and release that glucose into the blood stream until it has raised the blood sugar back to a normal level. When that person eats the next meal after the meal that resulted in a low blood sugar, their beta cells will release less first-phase insulin and avoid causing another low blood sugar.
In a healthy person, the first-phase insulin release peaks shortly after they’ve started their meal. The highest blood sugar level they will experience usually occurs by 45 minutes after they started eating.
Second-Phase Insulin Release
After completing this first-phase insulin release, the beta cells pause. But if the blood sugar is still not back under 100 mg/dl ten to twenty minutes later, beta cells start to secrete more insulin and provide another, smaller, second-phase insulin release whose job is to mop up the rest of the excess glucose circulating in the bloodstream. This second-phase insulin release continues as long as it is needed—until the blood sugar is back down to its fasting level. In a normal person, this usually takes about an hour to an hour and a half after the start of a meal.
It is this combination of a robust first-phase insulin release of stored insulin and a strong second-phase insulin release of secreted insulin that keeps the blood sugar of a normal person almost always under 100 mg/dl except for those few moments immediately after a meal before the first-phase insulin release kicks in. The system ensures that the brain and organs get a steady supply of glucose to fill their needs but prevents the build up of excess glucose in the blood stream that might clog up capillaries, gum up the kidneys, or inhibit the activity of nerves.
What are Truly Normal Blood Sugar Levels?
An illuminating research study presented by Professor J.S. Christiansen at the European Association for the Study of Diabetes conference in September of 2006 depicted the daily pattern of blood sugars in a group of normal subjects as it was revealed by the use of a Continuous Glucose Monitoring System (CGMS). The CGMS is a small computer attached to a probe. The probe is inserted under the skin where it samples the blood sugar every few minutes for a period lasting from a few days to several weeks. The computer stores and graphs this information.
Dr. Christiansen’s data is summarized in the figure above. A group of normal people wore the CGMS during the period spanning from when they woke up and ate breakfast until just before lunch. The heavy line shows the median blood sugar of the group as a whole. Next to it are thinner lines showing the top and bottom of the range within which most of their blood sugars fell. The lower set of lines represents their insulin and C-peptide levels. [NOTE: C-peptide is a byproduct of the manufacture of insulin. Measuring it is another way to measure insulin production.] The vertical line indicates the time when the study subjects ate a high carbohydrate breakfast.
The data collected from these normal people showed that throughout the night their fasting blood glucose concentration remained flat in the low 80 mg/dl range. After a high carbohydrate meal, their blood sugar rose to a median value near 125 mg/dl for a brief period.
This occurred about 45 minutes after they ate. In all but the people with the highest readings, blood sugar dropped back under 100 mg/dl by one hour and fifteen minutes after eating and it returned to 85 mg/dl by one hour and forty-five minutes after eating.
Note that even the highest of these normal readings is far below the cutoff most doctors consider to be the high end of “normal” which is 139 mg/dl measured two hours after eating!
Chapter Two: How Diabetes Develops
Now that you understand how the normal body controls blood sugar levels, it’s time to look at what happens when that control breaks down. Before we do that, we need to take a moment to discuss the tests doctors and researchers use to measure blood sugar performance and to learn the terms doctors use to describe the various stages of deterioration that lie between normalcy and diabetes.
The Blood Sugar Tests Doctors Use
Table 1 shows the diagnostic criteria used to define normal blood sugar, the intermediate stage called “prediabetes,” and diabetes. [NOTE: These criteria are set and periodically updated by a committee of experts appointed by the American Diabetes Association. Their choice of the specific cutoff points now in use is controversial and there is a lot of evidence that these criteria do not diagnose people until they have already had diabetes long enough to have developed diabetic complications that take years to emerge. You can read the details of how these criteria were chosen on Bloodsugar101.com at the subpage titled, Misdiagnosis by Design. The fasting criteria have changed several times, so current and historical ranges are both given.]
Fasting Plasma Glucose
When researchers measure blood sugar they can choose from a couple different techniques. One is the fasting plasma glucose test, abbreviated FPG, a simple test which requires only a single blood draw. This test measures the concentration of glucose in the blood after an eight hour fast. The FPG only gives information about how the blood sugar behaves in the fasting state.
The American Diabetes Association has defined some arbitrary values which are used to determine if a person is normal, if they have an intermediate form of blood sugar dysfunction called impaired fasting glucose (IFG), or if they have diabetes.
The ADA’s definition of what fasting plasma glucose test values should be used for making these diagnoses has changed over the years. Until 1998 the ADA defined a fasting plasma glucose over 140 mg/dl as “diabetic.” In 1998 they lowered the diabetes diagnostic cutoff to 126 mg/dl. The ADA has also lowered the value used to define the upward limit of “normal” several times. Its current value is 99 mg/dl.
This is why studies conducted before 1998 did not consider people to be diabetic unless their fasting blood sugars were over 140 mg/dl. Now that the diagnostic cutoff for the fasting plasma glucose test has dropped to 126 mg/dl, we know that a lot of people considered nondiabetic in older studies were actually diabetic, so some caution needs to be used when interpreting older studies.
The Oral Glucose Tolerance Test
The test used to track how first- and second-phase insulin release are holding up is the Oral Glucose Tolerance Test (OGTT). It is somewhat artificial in that it doesn’t measure how people respond to food, but rather it measures how their blood sugar responds after consuming a huge dose of pure glucose. Glucose does not need to be digested, so it goes directly into the bloodstream almost as soon as you eat it. As a result, the OGTT is a brutal test which causes intense blood sugar swings that are much more severe than those you would experience eating the same amount of carbohydrate in the form of food.
The procedure for administering an OGTT is this: Subjects who have been fasting are given a fasting plasma glucose test. They then drink a glass containing 75 grams of glucose dissolved in water. After this, their blood sugar is measured at stated intervals, usually one hour and two hours after drinking the glucose. If a person’s blood sugar is over 140 mg/dl two hours after drinking the glucose, the person is considered to have prediabetes or impaired glucose tolerance (IGT). People whose blood sugar is under 140 mg/dl at two hours are considered to be normal, though there is no functional difference between what is happening in the body of the “normal” person whose blood sugar is 139 mg/dl two hours after drinking glucose and in that of the “prediabetic” person whose blood sugar at two hours is 140 mg/dl.
During the OGTT, if the blood sugar reading is higher than 199 mg/dl at two hours, the person is diagnosed as diabetic, not because there is any functional difference between a blood sugar that rises to 199 mg/dl and one that goes to 200 mg/dl, but simply because the ADA’s Expert Panel arbitrarily chose this number as the level at which they would diagnose diabetes.
When discussing studies, any OGTT result cited is assumed to be a two hour result unless it is specifically described otherwise.
The A1c Test
The A1c test, which is also called the Hemoglobin A1c test and abbreviated hgA1c, is the test your doctor is most likely to rely on to track your blood sugar control over time. It is frequently used to measure blood sugar control in studies of large populations where it would be too expensive to perform individual glucose tolerance tests.
This test doesn’t measure the concentration of sugar in your blood. Instead, it measures how much glucose has become permanently bonded to the hemoglobin in your red blood cells. The higher your blood sugar has been over an extended period of time, the more likely it is that glucose will have become permanently bonded to your hemoglobin. The A1c test result is expressed as a percentage since it reflects the percentage of red blood cells of a certain type that have glucose permanently bonded to them.
A normal A1c value is one between 4.0 and 5.0%. People with diabetes usually have A1cs ranging from 6.0% to as high as 15.0%.
Doctors use various formulas to compute the average blood sugar that they believe matches an A1c test result. The most commonly used formula is:
Average Blood Glucose = (A1c * 35.6) - 77.3
Because red blood cells usually live around three months, most doctors believe that the A1c reflects three months’ worth of blood sugar control. However, studies suggest the A1c result largely reflects your blood sugar control in the two weeks before you took the test. Studies have also found that the height of post-meal blood sugar spikes greatly influences the A1c result in people with near normal blood sugars.
The fasting blood sugar plays a larger part in raising the A1c when the A1c approaches 7.0%.
The A1c test will only reflect your average blood sugar control if you have a normal population of red blood cells. If you are anemic, by definition you have an abnormally low number of hemoglobin cells. This means you’ll also have a deceptively low A1c reading, no matter how high your blood sugars have been in the period before the test.
Your A1c result may also be inaccurate if your red blood cells live longer or shorter than usual. Long-lived red blood cells can give a falsely high A1c reading because they continue to collect glucose during their longer lives. If your red blood cells are living shorter lives, they have less time to collect glucose. People with certain genetic variants of the red blood cell, including the sickle cell, also will get misleading A1c results.
The Patterns in Which Diabetes Develops
Now it’s time to learn how normal blood sugar deteriorates into diabetes. We’ll start out by looking at what two long-lasting studies of large populations have to teach us about the stages in which blood sugar control breaks down. Then we’ll examine what is actually happening in your body during each of these stages.
A Landmark Study of Middle Aged People
Data from the Baltimore Longitudinal Study of Aging shows that over a period of ten years, the blood sugar of 48% of a large group of people in their 50s remained normal. Of the rest, 52% developed abnormal blood sugars, including the 11% who developed blood sugars bad enough to be diagnosed as diabetic.
By far the most prevalent pattern of blood sugar deterioration found in this group was the development of impaired glucose tolerance with normal fasting blood sugar. [NOTE: The upper cutoff for normal fasting blood sugar used in this study was 110 mg/dl. ] This means that their blood sugar was higher than 140 mg/dl two hours after consuming glucose but their fasting blood sugar remained under 110 mg/dl. It also probably implies that they were seeing blood sugars well over 140 mg/dl two hours after eating any meal containing carbohydrates.
Only 5% of the study subjects—one in twenty, developed the reverse pattern of impaired fasting glucose occuring with normal glucose tolerance, while only 3% simultaneously developed both impaired glucose tolerance and impaired fasting glucose.
This makes it clear that it is far more common for post-meal blood sugar response to deteriorate before fasting blood sugar becomes impaired.
The Most Common Pattern for Those Developing Type 2 Diabetes
When the researchers turned their attention to the subset of people with abnormal blood sugars who had gone on to develop full-fledged diabetes, they found that, like the group as a whole, as they deteriorated they were much more likely to get abnormal two hour glucose tolerance test results while still having normal Fasting Plasma Glucose test results. Only a small number developed impaired fasting glucose while maintaining normal glucose tolerance.
This makes it very clear that deterioration of glucose tolerance—which implies deterioration in how blood sugar rises after a meal—is often the only apparent sign that a person is heading towards diabetes. For most people, the fasting blood sugar stays normal long after the meal-time control has faded out.
Of critical importance, in this study, two thirds of the people who were diagnosed as having diabetes using the glucose tolerance test had not yet developed impaired fasting glucose. Unfortunately, most doctors screen patients for diabetes using only the fasting blood sugar test since it is cheap and very easy to administer, unlike the time-consuming OGTT. Those doctors will not diagnose people who have become diabetic until much later in the deteriorative process.
This is why if you or a loved one are at risk for having diabetes you must insist that your doctor give you an OGTT. If that is not possible, buy a blood sugar meter and test your blood sugar after meals. That way you can learn if you have abnormal post-meal blood sugars early on, when you can still intervene and preserve your fasting blood sugar control and with it the lives of your remaining beta cells.
The Risk of Diabetes
he Baltimore Longitudinal Study of Aging diabetes study also found that a person in their fifties who has normal blood sugar has roughly a 1 in 8 chance of becoming diabetic over the next decade. A person who already has impaired glucose tolerance has a 4 in 10 chance of progressing to diabetes over a decade while a person with impaired fasting glucose has almost a 1 in 2 chance of progressing to diabetes.
Again, this suggests that fasting blood sugar control is the last part of blood sugar control to deteriorate.
Who Progresses?
The Baltimore Longitudinal Study of Aging data gives us some further insight into who develops diabetes in which pattern.
When analyzing data about the people who progressed to full-fledged diabetes, the researchers found that people older than 56 years were more likely to first develop impaired glucose tolerance than were younger people. The risk of developing impaired fasting glucose was about the same for all age groups.
They also found that men were more likely to see a deterioration in their fasting glucose than women, as were subjects with overall or central obesity when compared with lean subjects.
A Second Study Finds Diabetes Does Not Develop Gradually Another interesting study conducted in a large population looked at how the blood sugar of the individuals in that study changed over time.
The researchers studied a population of people living in Mexico City who were deemed to be at risk for diabetes. Every three years they measured the subjects’ fasting plasma glucose and their fasting insulin levels. They also administered oral glucose tolerance tests.
The researchers in this second study found that rather than being a gradual process, the transition to diabetes appeared to occur very quickly within a single three year period and that it was characterized by a sudden and very swift increase in fasting glucose values.
A Swift and Unexpected Deterioration in Blood Sugar Control Precedes the Diagnosis of Diabetes
One in twelve of the study subjects went from having normal glucose tolerance to having full-fledged diabetes during the three years between one examination and the next. Slightly fewer—One in fourteen—went from having impaired glucose tolerance to diabetes over the same three year period.
While the fasting plasma glucose of those who did not become diabetic increased “slightly and in an apparently linear manner,” that of the people who became diabetic took a sudden step up, showing an average gain of 50 mg/dl between one examination and the next, three years later. The two hour oral glucose tolerance test results showed a similar pattern. The people who did not become diabetic showed a “slight increase” in their blood sugar values on the OGTT over the three year period while those who became diabetic saw an average surge of 108 mg/dl between one exam and the next, three years later.
That this change was very sudden was highlighted by the discovery that the people who became diabetic during one three year period had shown very little change in their blood sugars over the three year period before the one in which their blood sugar deteriorated so swiftly. In fact, the changes in their blood sugar in that earlier period were the same as those in people who stayed normal.
This sudden and rapid deterioration after a period where blood sugar response stays relatively constant may happen when the post- meal blood sugar level finally rises above the threshold where insulin resistance suddenly increases dramatically and where glucose toxicity starts to poison beta cells.
What this study didn’t discover, but many of us active on the Web have found to be true, is that just as blood sugar control appears to deteriorate dramatically when you hit a certain high blood sugar threshold, when you take the steps needed to bring your post-meal blood sugars down below that critical level, you will often see a similarly dramatic rate of improvement.
What Happens at Each Stage of Breakdown?
Prediabetes
Remember the two stages of post-meal insulin release we described in Chapter One: The first-phase release of insulin that was previously stored in granules and the second-phase release of insulin secreted in real-time by your beta cells? Well, for most people, the first stage in the breakdown of blood sugar control happens when the first-phase insulin release after a meal stops working properly.
When you don’t get a swift release of stored insulin as soon as you start to eat a meal containing carbohydrates, your blood sugar will rise much higher than a normal 125 mg/dl. Now all you can rely on to lower your post-meal blood sugar is the slower, weaker second- phase insulin release that only kicks in about a half hour after you start eating. This second-phase insulin release is slow because it requires your beta cells to secrete insulin rather than use the insulin they previously stored. Now rather than peaking no more than 45 minutes after eating, the highest blood sugar you see after a meal will occur at least an hour after eating, possibly later. After it peaks, it may take another hour or longer for your blood sugar to return to normal.
This is clearly no longer normal. But it is not until the blood sugar remains above 139 mg/dl two hours after eating that doctors will diagnose prediabetes which is also known as impaired glucose tolerance (IGT). A diagnosis of prediabetes is a very strong sign that your first-phase insulin release has been failing for a while and that you are now relying on second-phase insulin release to return your post-meal blood sugars to a normal level.
Many people remain prediabetic for the rest of their life and never progress to diabetes. Even so, they may develop what doctors consider to be diabetic complications. This is because when you rely on your second-phase insulin release to control your blood sugar level after eating, it may take as many as three to five hours for your blood sugar level to return to normal. Since you eat every couple hours during the day, you will rarely get back to a normal blood sugar level between meals. This is a huge problem, because, as you will see in Chapter Four, scientists are discovering that it is hours of exposure to blood sugars in the so-called prediabetic range that cause diabetic complications.
Diabetes
The American Diabetes Association defines several different criteria for diagnosing diabetes. One states that a person should be diagnosed with diabetes when a random blood test reveals a blood sugar level higher than 200 mg/dl. By the time this has happened, you have usually lost all of your first-phase insulin release and are relying on a weakened second-phase insulin release to bring your blood sugars back down after eating. If you continue to let your blood sugars rise very high after meals, eventually your second-phase insulin release will fade out too, and you will end up with blood sugars that spend most of their time at the extremely high blood sugars characteristic of people diagnosed with diabetes—blood sugars that range from 200 to 500 mg/dl.