Glycemic Index Is Unreliable

It is about time! High variability suggests glycemic index is unreliable indicator of blood sugar response and much more. I know that the only solution is to use your blood glucose meter and your test strips to determine how you react to each food and type of food.

What surprises me the most is why it took so long to make this known. Consider that the glycemic numbers were developed using healthy people and not people with diabetes. For years many of us with diabetes have been saying that we have found the glycemic numbers have not matched what our meters tell us and are often even well outside the 15 percent possible error for the test strips we use.

The glycemic index of a given food, a value that aims to quantify how fast blood sugar rises after eating it, can vary by an average of 20 percent within an individual and 25 percent among individuals, report scientists from the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HRNCA) at Tufts University.

The study, published in the American Journal of Clinical Nutrition on Sept. 7, suggests glycemic index has limited utility as a tool to predict how a food affects blood sugar levels.

Developed as a way to help diabetic individuals control their blood sugar, glycemic index is intended to represent the inherent effect a food has on blood sugar levels. However, the glycemic index is becoming used for broader purposes such as food labeling, and has served as the basis for several popular diets.

"Reports frequently tout the benefits of choosing foods with low glycemic index and glycemic load values. Our data suggest those values may not be reliable in terms of a daily intake. A better approach to choosing foods is to consume a diet primarily composed of vegetables, fruits, whole grains, nonfat and low-fat dairy products, fish, legumes (beans), lean meats with preference to preparing food with liquid vegetable oils, and equally as important, to choose healthy foods and beverages you really enjoy," said senior study author Alice H. Lichtenstein, D.Sc., senior scientist and director of the Cardiovascular Nutrition Laboratory at the USDA HNRCA. Lichtenstein is also the Gershoff Professor at the Friedman School of Nutrition Science and Policy at Tufts.

The variability in glycemic index values occurred despite sample sizes larger than required by standard calculations. The study cohort of 63 individuals far exceeded the 10 individuals used by typical glycemic index methodology, as did the six feeding challenges and five-hour blood glucose measuring window.

The team also tested for the influence of biological characteristics: sex, body-mass index, blood pressure, physical activity, and several others. Most factors had only a minor statistical effect on glycemic index variability. Blood insulin response as measured by insulin index and HbA1c, a measure of longer term glucose control, had the largest effect, accounting for 15 and 16 percent of the variability, respectively.

Is the Glycemic Index Useful for People with Diabetes?

This is an interesting short article from a doctor at the Mayo Clinic. M. Regina Castro, MD is the doctor and I can appreciate some of her comments about the glycemic index.

Some people with diabetes use the glycemic index (GI) as a guide in selecting foods for meal planning. Other people won't use it as a guide, but as the food bible in selecting the foods they consume. The glycemic index classifies carbohydrate-containing foods according to their potential to raise your blood glucose level. Foods with a high glycemic index value tend to raise your blood glucose higher than do foods with a lower value.

There are a few benefits in using the glycemic index, but be careful not to slip into some of the common traps. Some of the traps include:

• Single food items, rather than combinations of foods, can impact blood glucose differently
• Doesn't consider all variables that affect blood glucose, such as how food is prepared or how much is eaten
• Only includes foods that contain carbohydrates
• Doesn't rank foods based on nutrient content — foods with a low GI ranking may be high in calories, sugar or saturated fat

Why the doctor is concerned about saturated fat tells me that she still believes the low fat high carbohydrate way of eating and cannot accept the low carbohydrate high fat way of eating.

It can be difficult to follow the glycemic index. For one thing, there is no standard for what is considered low, moderate and high glycemic foods. Packaged foods don't list their GI ranking on the label, and it can be hard to estimate what it might be. The doctor also misses the glycemic load (GL), which can be useful in determining some foods that are good for you. To begin with, packaged foods need to be avoided by people with diabetes because they will raise your blood glucose levels higher and faster than other foods.

Basic principles of healthy eating, portion control and counting carbohydrates are all ways to help you better manage and control your blood sugar. If you're interested in learning more, talk to a registered dietitian. Warning! Be very careful as most registered dietitians will only push carbohydrates and not be concerned about the glycemic index. Instead of helping you make wise food choices or help with your eating habits, they will mandate whole grains and other foods that will require larger doses of medications. Don't worry, they will be happy to advise your doctor that you need this or additional medications.

Points to Consider About Food

The glycemic index (GI) and the glycemic load (GL) are two of the more meaningful terms in understanding the value of food and how each affects our blood glucose levels. This is a topic everyone with diabetes needs to be aware of and learn the general principles.

Everyone also needs to be aware that to some this is a religion, and therefore they can endanger their health. I will warn that this topic and the principles behind this should be used as a guide, but not as a bible. First, the glycemic values were determined using healthy people and not patients that were obese or that had any diseases. Therefore, we cannot be positive that the tables are exactly right for us. We do need a starting point, so I accept the tables as a starting point.

I will direct your reading to several people that have influenced my thinking about the glycemic index and glycemic load. The first was this book - The New Glucose Revolution, New York, Marlow & Company, 349 pages, by Dr. Jenny Brand-Miller, et al. I currently have the third edition.

Computing the glycemic load is fairly easy and will help in determining whether you are safe in eating the particular food, or will have high blood glucose levels briefly or for a longer period. Using the example from a blog by Dr. William Davis, we have the following: (quoting) “GL = (GI x amount of carbohydrate) / 100.

GL is therefore the GI that incorporates the glycemic potential of the food of interest. GI does not vary with portion size; GL varies with portion size.

Let’s take whole-wheat pasta, a food regarded by most people as a healthy choice. Whole-wheat pasta has a GI of 55–fairly low–and a GL of 29. A serving of 180 g (approximately 6 oz cooked) provides 50 g carbohydrates.” So using the formula above the GI of 55 X 50 g carbohydrates = 2750 divided by 100 = 27.5 for GL – not the 29 that Dr. Davis has. In either case when you look at the graph from David Mendosa's web site, you will see that the GI of 55 is the top end of the low range and the GL is well into the high range. This means that the whole-wheat pasta will raise blood glucose for a long period. This will depend on your body chemistry so actual time is difficult to measure. This is a good reason to avoid whole-wheat pasta.

Doctor Davis also has another blog on the glycemic index. By entering “glycemic index” in the search box on David's site, it will return many more articles by David and many that you may wish to read. Here and here are two of the articles.

If you have more interest in blogs on glycemic index go to this site and subscribe for a monthly newsletter.

Back to Diabetes Basics – Part 5

Diabetes Complications

Complication don't cause themselves. Poor or no management of diabetes – meaning not testing, not losing weight, not eating healthier, not making other lifestyle changes, and no blood glucose management is what causes the complications. So what are the complications?  Retinopathy, neuropathy, nephropathy, atherosclerosis, and deafness are the most common, and many don't include deafness. The first three and deafness are grouped together under the term microvascular complications because they result from damage to the small blood vessels. The macrovascular complication is atherosclerosis, which is caused by damage to the large blood vessels.

Retinopathy causes damage to the retina, which may lead to poorer eyesight or blindness. Neuropathy causes damage to the nerves, which cause pain and can be more than annoying pain. Nephropathy causes damage to the kidneys or increased renal problems leading to kidney failure or chronic kidney disease (CKD). Deafness or hearing loss is caused by the eardrum losing the ability to transmit sound because of short blood supply. Atherosclerosis can lead to heart attacks, stroke, or poor healing of wounds in the feet and legs. This is the cause of amputations.

These are the reasons those of us that blog about diabetes for people with type 2 diabetes discuss this so often. We are encouraging you to manage your diabetes by maintaining your blood glucose levels at or as close to normal as possible to prevent the complications from starting. The closer your A1c is to 7.0 percent or above, the greater the chances are for the complications developing. That does not mean that people with A1c's of 6.0 will not develop complications, just that their risks are smaller and increase the closer to 7.0 they become. Above 7.0, the risk of complications rises dramatically as A1c's goes up.

That does not mean that once you have an A1c above 7.0 that you give up. By managing your diabetes more carefully and bringing the A1c back to 6.0 or lower, you can stop the complication from progressing or slow it dramatically. Damage will still likely have been done, but if stopped or slowed, you may not notice any change and if early enough your body may be able to heal the damage. Continued forays above 7.0 may mean that the damage will become worse and your body may not be able to heal or repair the damage. Keep a positive attitude about managing your diabetes and work to manage your diabetes and not diabetes managing you.

Diabetes Myths

Diabetes myths are a dime a dozen and I keep hearing about them again and again. Why people have to believe them is not something I understand. I was not exposed to many of them until after I had diabetes for a year and had been on insulin for about as long. I knew immediately when confronted with them by a person that is no longer a friend that there was little or no truth in what he was telling me. In an hour, I lost track of the number of myths he was repeating and finally had to ask him to leave.

That evening after cleaning up after my evening meal, I did go on the computer looking for some of what this person was telling me. Even then, there was not a lot of information about some of what he said. I started looking on David Mendosa's website, but even he did not have a lot in December 2004 about what we refer to now as myths. I did locate this item and it got me started looking for more. Eventually I did find a site that today no longer has the page David wrote about, but back then, it was as David described it, “While several Web sites around the world have a page like this, Diabetes UK's is the best and most authoritative of any that I've seen.”

I now wish I had copied the page, as I am no longer able to locate it. They covered a lot of myths and then gave an authoritative explanation. There were sites that listed myths with no explanation, but many were like or similar to things my visitor had sought to enlighten me. The following evening, he returned with a fresh list and wanted to educate me with his diabetes knowledge. I patiently informed him that these were myths and had no basis in fact or scientific evidence. He went ballistic on me and said I did not know what he was talking about and if I truly had diabetes, I would understand what he was saying. With that, I walked him to the door and informed him that I had diabetes and was on insulin. “Oh,” he said, “I did not know you were that close to the end.” I then told him to leave and never come back if he was going to talk about diabetes.

I have also blogged about diabetes myths. Rather than repeat them, I will link them and let you read them - Blog 1, Blog 2, and Blog 3. Another blog that talks about a myth here and then this one on insulin and weight gain which is often a fact for many people, unless they are aware of the things to do right and prevent this from happening. One myth that I find little to support was told to me by a diabetes educator and it was that type 2 people could not see an endocrinologist. Funny, I see many type 2 people having appointments with an endocrinologist.

Diabetes Scams and Scammers

Diabetes is ripe with scams and scammers. To get you started, read this article by David Mendosa. In the article, the government list no longer is a valid link, but David did list some of them and I don't know if they all work, but I like the list just for show of the types of sites trying to scam us. Many more have appeared since David wrote this in October 2006. Some sites are very slick in their design and enticing to any readers they can lure to their sites. I have had several email me in the last year wanting me to advertise their products. After a thorough investigation of their site and the claims some make, I can see right through the scam or falsehood, if you will allow.

I am unlike David and I will not even give you a link to any scamming site as I will not give them any notice since they do not deserve being noticed. Yes, I could educate you by listing them, but I don't need the hate mail several of them are well known to retaliate. There would still be readers that would fall for some of the information so I feel better not listing them.

If you think these are the only types of diabetes and other scammers, guess again. Tom Ross has a blog here that uncovers some that are involved in research and scamming funds to do research. I was almost in disbelief, but after checking with a couple of sources within the pharmaceutical industry, they confirmed this blog, but would not be specific about what had been done.

Food for Diabetes Patients and Introduction to Glycemic Index

This is not a topic to be taken lightly by people with type 2 diabetes. However, the one comment I get all too frequently is, “the doctor just told me to eat more healthy,” or “my doctor said nothing about what foods to eat or not eat.” I often have to wonder if this is selective hearing, or the doctor really did say nothing. I know many doctors are not knowledgeable in nutrition for people with diabetes so this is possible. I also know some people bypass the appointments for a class in nutrition and feel it is too late for them to change. Unhappily their A1c results are reflective of their habits – above 8.0 and often much higher.

Even though I am a little over expressive in this blog on diabetes diet, it still covers some important points. Another blog is here. I have mentioned the glycemic index for foods. The best reference is here in the books blog, The New Glucose Revolution, New York, Marlow & Company, 349 pages, by Dr. Jenny Brand-Miller, et al. It is in a sense the best available currently.

Do take time to study the glycemic index tables for foods. Do not believe these are gospel because the index is determined by testing normal people and not people with diabetes. Do use it only as a guide for determining which foods may rapidly raise your blood glucose. By using your search engine, there are many available (key words – glycemic index). Table sugar has a glycemic index of 80, so compare that to the white potato.

My words of warning are good, and a guide is what it should be. It is not about complete food nutrition and is good for giving you guidance to foods that will not spike your blood glucose levels.

Series 5 of 12