AboutSheri Colberg, PhD Expertise I am an exercise physiologist with a PhD who specializes in diabetes. My expertise lies in answering questions about diabetes (of any type) and physical activity. I can help you if you want to begin exercise or if you're already a diabetic athlete, and I am prepared to respond to questions about physical activity to which even your diabetologist may not know the answer. I can give suggestions about changes in your diabetic medications that differing types and intensities of exercise may necessitate, but I will have to refer you to your regular health care team to get final approval to make such changes. I can also answer questions about physical fitness, exercise metabolism, prediabetes reversal, and prevention of type 2 diabetes and diabetic complications.
Experience I have both personal and professional experience in the areas of diabetes and exercise. On a personal level, I have had type 1 diabetes since 1968, and I have been an avid exerciser since I was a child. Professionally, I have been conducting clinical studies on diabetes and exercise since 1992, largely with funding from the American Diabetes Association. I am also the author of four books related to diabetes and exercise: The Diabetic Athlete (2001, but soon coming out in a 2nd edition), Diabetes-Free Kids (2005), The 7 Step Diabetes Fitness Plan (2006), and 50 Secrets of the Longest Living People with Diabetes (2007).
Organizations I am a Fellow of the American College of Sports Medicine, a professional member of the American Diabetes Association, and a member of the Board of Directors of the Diabetes Exercise & Sports Association.
Publications I have published research and review articles in the following journals and magazines: Diabetes Care, Diabetes, Journal of Diabetes & Its Complications, Diabetes Self-Management, Medicine & Science in Sports & Exercise, Journal of Applied Physiology, The Physician and Sportsmedicine, Journal of Clinical Investigation, International Journal of Obesity, FASEB Journal, The Diabetes Educator, Journal of Physical Education, Recreation, and Dance, Clinical Exercise Physiology, Clinical Diabetes Reviews, Insulin, ACSM's Health & Fitness Journal, Biomechanics, On the Cutting Edge, Diabetes Technology & Therapeutics, Microvascular Research, Drug Benefit Trends, ACSM Certified News, Diabetes Health, SportEX Health, Diabetes Focus, Diabetes In Control, dLife-For Your Diabetes Life, Pediatrics for Parents, and My TCOYD (Taking Control of Your Diabetes) Newsletter. I have also been interviewed in myriad other magazines, such as Men's Health, Men's Fitness, Diabetes Forecast, Countdown Magazine, Joe Weider's Muscle & Fitness, Health, Tidewater Parent, Barron's News, Diabetes New Day, and Newsweek International.
Education/Credentials I have an undergraduate degree (1985) from Stanford University, a Master's degree in exercise physiology (1987) from the University of California, Davis, and a Ph.D. (1992) from the University of California, Berkeley, in the same field. I also spent two years in an NIH-funded postdoctoral research position in endocrinology (studying obesity, diabetes, metabolism, and exercise) at the University of Pittsburgh School of Medicine (1993-1994).
Awards and Honors Fellow, American College of Sports Medicine (FACSM) - 1996
Old Dominion University Darden College of Education Young Investigator Grant Award 2003
Academic Keys Whos Who in Education 2003-2007
Marquis Whos Who in America 2004-2007
Honor Society of Phi Kappa Phi, Old Dominion University Chapter 2004-Present
Great Women of the 21st Century by the American Biographical Institute 2005 Edition
Marquis Whos Who of American Women Included in 2006-2008 Editions
Marquis Whos Who in Medicine and Healthcare Included in 6th Edition, 2006-2007
Old Dominion University Darden College of Education Largest Research Grant Award 2006
Old Dominion University Darden College of Education Publications Award (for greatest number) 2006
Past/Present Clients I have consulted for numerous groups, including the California Commission on Peace Officer Standards and Training(about candidates with diabetes), Animas Corporation (an insulin pump company), Therasense, Inc. (makers of the Freestyle blood glucose meters), Council of Healthcare Advisors, and the City of Chesapeake (Virginia) Health Department.
Question QUESTION: 10 months ago I had a routine blood test and was told that I had pre-diabetes. My fasting blood glucose reading was 102 mg/dl. I did a lot of research online about pre-diabetes and diabetes and decided to adopt the paleolithic (hunter-gatherer) way of eating. I have strictly followed this mode of eating for the past 10 months without exception. Note: Prior to the change in my diet, I was a heavy consumer of carbohydrates especially cereals, rice and sugars; I was on a high-carb low fat diet. Every month, I have my blood glucose tested and below are the results with comments:
Date Glucose Comment
07/12/07 102 Initial reading
08/14/07 92 Went on Paleolithic diet
09/14/07 95
10/18/07 106
12/06/07 91 Cut back of sugary fruits
01/07/08 87 Elimiated sugary fruits
01/15/08 69 Elimiated all fruits
02/14/08 85 Still not eating fruits
02/21/08 74 Still not eating fruits
03/20/08 100 Still not eating fruits
04/23/08 102 Re-introduced fruits (max 4)
05/23/08 109 Still restricting fruits
Relevant facts:
Age= 49
Health = Excellent
Weight = 148 lbs
Height = 59
Exercise = Rigerous exercise (aerobic & strength training) 5 time per week approximately 1 hour each session.
Diet = Paleolithic = No grains, no starchy foods, no dairy, no processed food, no salt, no sugar/honey/sweeteners, lean meats, olive oil only, pleanty of fresh vegetables etc, etc.
Questions/Comments
It seems that my fasting blood glucose levels were not significantly affected by moving to a low-carb Paleolithic diet - they ranged between 91 & 106. After reducting my intake of sweet fruits, I saw a reduction in my fasting glucose level to around 87. When I eliminated fruits altogether, my fasting blood glucose level initially fell very significantly to between 69 & 85 mg/dl. However, after about two month without fruits, my fasting blood glucose level went back up to 100 mg/dl. It seems that my body adjusted to the reduced intake of carbs and sugars by producing glucose from other food sources, i.e. protein and fat causing my blood glucose level to return to a level similar to what it was before I eliminated fruits.
Is it possible that my body mechanism has determined at a fasting blood-glucose level of 100 to 110 mg/dl is normal and necessary for me maybe as a consequence of the requirements that I place on my body as a result of my intensive exercise regime??
Since I re-introduced fruits (4 per day) my fasting blood glucose level has started to rise again (102 to 109 mg/dl) and is now in fact higher that when I was first diagnosed with pre-diabetes. Do you have any idea why this could be occurring.
Do you think it would be a good idea for me to:
i) Have further tests, e.g. glucose tolerance & insulin, to attempt to get to the root cause.
ii) Should I get my own blood glucose tester and start to test myself through-out the day to get a better picture of my blood-glucose profile
iii) Do you consider it a good idea for me to further reduce my consumption of carbs? I now consume approximately 130 grams of carbs per day.
ANSWER: Royston,
You have studied yourself very scientifically, and I'm sorry you haven't had better results. There are so many things that can affect insulin action that it's hard for me to guess at what is really going on with you. With the regular exercise and excellent diet, though, I don't see that it's anything you're doing wrong necessarily. How are your stress levels? That is one thing that can negatively impact insulin action. Also, was there anything different from one month to the next that could have affected your results, such as lack of sleep before testing or not exercising sometimes and working out the day before other times? A number of individuals nowadays are developing type 1 diabetes later in life as well (LADA, or latent autoimmune diabetes of the adult, a subtype of type 1), which you could be at the start of if your fasting sugars continue to rise over time.
Suggestions? You certainly could get an oral glucose tolerance test done to see how you react, although that may not give you any definitive answers. If you can afford to, getting your own blood glucose meter (they're not that expensive) and then testing at various times of day, before/after meals and exercise, etc. may give you more answers. The strips are expensive though (about 60 cents each without reimbursement) unless you can get an Rx for them from your doctor. As for your carbs, I wouldn't recommend further lowering them as that may negatively affect your ability to exercise almost daily; plus I don't think that is the answer. Something else you could try, just to see if your liver is overproducing glucose at night and giving you the slightly higher fasting readings, is to drink a glass or two of wine or beer the evening before you have your next fasting test done. Alcohol decreases the liver's ability to make glucose, and for some people, it causes lower fasting glucose readings the morning after.
I don't have any other ideas for you to try at the moment. You might want to read an article I wrote about all the things that can impact insulin action (http://www.insulitelabs.com/articles/enhancing_insulin_action.html), and there are other ones on my web site at www.shericolberg.com and blog. Insulite Labs has a pre-diabetes program that also includes neutraceuticals that you may want to look into as another option: http://pre-diabetes.insulitelabs.com. The neutraceutical part is about the only one that it sounds like you haven't tried already.
Good luck with it! Sheri
---------- FOLLOW-UP ----------
QUESTION: Thanks for your comprehensive answer and encouragement :) I have looked at the information references that you sent me especially the neutraceutical. I will consider purchasing some of the herbs/vitamins recommended to see if that has an impact. However, for the past few months, I have been taking the extract of bitter melon, together with 3 grams of fish-oil and a gram of garlic approximately 4 or 5 days a week after reading about their positive health benefits and their potential to improve insulin sensitivity. I will also have the glucose tolerance test done and purchase a glucose meter to see if this further testing can shed any further light on what is happening with me.
I did not mention some other details that may be relevant to my case:- When I was diagnosed with pre-diabetes, I was also told that my total cholesterol level was borderline high. The total measure was 220 mg/dl with HDL of 136 and LDL of 70. I was not too concerned about the overall reading because my HDL was high and the ratio of Total to HDL was also good. However, since starting on the Paleolithic diet my total cholesterol reading have generally increased after falling initially and the reading is currently around 260 mg/dl (see below for details):
I speculate that the increase in my total cholesterol may be due to my increase meat consumption resulting in an increase in my intake of saturated animal fat NB: I went from a low-fat, high carb diet to a high protein & relatively high fat (Paleolithic) diet I consume quite a lot of virgin olive oil.
I am now wondering whether there may be a relationship between the increase in my fasting blood glucose level and the increase in my total cholesterol.
On a more positive note, I have noticed that since re-introducing fruits into my diet I am feeling stronger, fitter and more energetic. I run competitively and when I eliminated fruits (and therefore cut carbs) from my Paleolithic diet my performance deteriorated significantly. Also, my resting heart-rate increased and I was not longer able to finish races with a burst of speed. Now that I reintroduced limited fruits (4 per day), Im back to my energetic self and my resting heart-rate is back down to around 45 beats per minute. In fact, I now seem to have better endurance for distance events. I speculate that the period when I ate extremely low-carbs re-trained my body to burn fat more efficiently as an energy source and I am now deriving the performance benefits of this.
So apart from my elevated blood glucose reading, I am feeling good physically and mentally. That why I am wondering whether it is possible that a fasting-blood-glucose reading of between 100 and 110 could be ok for me given my eating habit and extensive exercise regime. In order words, could it be that for certain individuals, higher than normal/average blood glucose reading are healthy?
Let me not risk boring you with any more of my personal situation as I could probably write about this all day its therapeutic just to be able to talk' to someone knowledgeable about my situation. However, I realise that I may by over-analysing everything! Thanks again for being so helpful.
Royston
Answer Royston,
Do you remember if you had symptoms like a higher resting HR when you were off of fruits and your blood sugar starting increasing? Any type of physical stress (such as overtraining with low carb intake) can also increase your levels of cortisol, which is a hormone that can bump up your fasting blood glucose levels. I don't know that the medical community would consider 100-110 as normal for a fasting level, even with all that you do right. Some studies have shown that men's heart disease risk is increased even if their blood glucose levels rise above 85, but still stay in the normal range. As for your cholesterol, we are still learning more about what it all means. If you're concerned, you may see if you can get them to subtype your subtypes as there are different types of LDL, some of which are actually harmless (the big, fluffy type) as opposed to the small, dense LDL that contribute to plaque formation. If it's your fluffy LDL that increased, it's not as concerning. Higher cortisol levels can also elevate triglyceride levels, which can raise cholesterol, but in your case, I can't say for certain whether they're related.
If the neutraceutical work for you, let me know! Sheri
