Endocrinology (including Diabetes)/Blood Sugar Levels


QUESTION: Dear Dr. Colberg,

I monitor my gluc levels with the One Touch Ultra 2 glucometer.  I have it calibrated correctly.  

I am a 40 y/o active male, eat healthy, and am probably 18% body fat...so I could lose maybe 5 lbs of belly fat even though I do not look chubby, fat, or anything like that...I'm just not a stick (thin).

My gluc levels are pretty consistent and even...even after a meal.  The highest I've ever seen it was 161, and that was right after playing a couple hours of tennis and having chocolate milk.  It's almost always about 83 prior to bed time.  

Most of the time when I wake up it's about 85-90 but sometimes it will be 100, even 110 once when measured at the hospital after 12 hour of fasting.  These times it's 100 when I wake up it is always around 83 before sleeping.  

Is it a concern that it is increasing (sometimes) when I sleep? It's even longer since food's been eaten so I am concerned about the rise in gluc levels when I wake up.  Again, it's not every day, but often enough.  


ANSWER: What you mentioned is a fairly common phenomenon--elevated fasting blood glucose levels.  For some reason, in many people their livers overproduce glucose overnight.  The liver is normally responsible for keeping blood glucose levels constant during the day and particularly overnight when you go 8 or more hours without eating.  The only things I know of that may have an effect on fasting levels (to keep them lower) are drinking an alcoholic beverage in the evening (like a glass of wine) as alcohol interferes with glucose production by the liver and taking melatonin as an over-the-counter supplement at bedtime.  in people with diabetes or prediabetes (the fasting range for the latter is 110-125 mg/dl), a medication called Metformin is often prescribed that also appears to lower glucose production by the liver overnight.  It sounds like you may be doing what you need to with your lifestyle, although losing a bit of your belly fat would probably help as well.  Sheri

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QUESTION: Thank you very much for the explanation Dr. Colberg!  :)   It helped shed light on something I knew nothing about.  So if my gluc levels are fine throughout the day (and they are...I've bee checking quite often to see where I'm at and if I'm at risk for diabetes), and sometimes up to 110 when I wake up, despite being maybe 75-85 when I go to bed, would you say I'm "pre-diabetic" or normal?  My wake up gluc levels isn't always 110.  Over the last few days here's a sample of what they've been: 110, 84, 85, 88, 91, 99, 102,  84, 92, 98, 93, 101, 103, 92, 97, 89, 107.  As you can see mostly at or under 100, with a couple at or near 110.  But it's almost always 10-20 points higher than when I go to bed (and I don't eat in my sleep lol).  

Anyway I GREATLY appreciate your taking the time to help me out.


  I wouldn't be too concerned at this point, although it is something to watch over time.  Many people develop just high fasting blood glucose levels and do fine during the day.  Home blood glucose meters are somewhat inaccurate, so you can't swear by the numbers that you're seeing.  At some point, as your doctor to run an A1C test when you have a checkup because that gives feedback on your overall BG readings over 2-3 months.  Try to keep your belly fat down, too, as that can contribute to the rise in fasting BG levels.  I have lots of article about making useful lifestyle changes on my web site (www.shericolberg.com) that may help you to look through some time as well.  Sheri

Endocrinology (including Diabetes)

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Sheri Colberg, PhD


I am an exercise physiologist with a PhD who specializes in diabetes--as such I CANNOT answer general questions about other endocrine problems as I am neither an expert in all areas of endocrinology nor am I a medical doctor. My expertise lies in answering questions about diabetes (of any type) and physical activity, so please limit your questions to those areas. 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.


I have both personal and professional experience in the areas of diabetes and exercise/physical activity. 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 8 books related to diabetes, exercise, and more: The Diabetic Athlete (2001), Diabetes-Free Kids (2005), The 7 Step Diabetes Fitness Plan (2006), 50 Secrets of the Longest Living People with Diabetes (2007), The Science of Staying Young (2007), Matt Hoover's Guide to Life, Love, and Losing Weight (2008), Diabetic Athlete's Handbook (2009), and Diabetes? No Problema! (2009).

I am a Fellow of the American College of Sports Medicine, a professional member of the American Diabetes Association (and professional volunteer for the ADA), and a former member of the Board of Directors of the Diabetes Exercise & Sports Association.

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.

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 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 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 Saint Louis University, The Max K. Horwitt Memorial Lecture Distinguished Lectureship Award 2008 Old Dominion University Darden College of Education Publications Award 2009 Old Dominion University Darden College of Research Grants Award 2009

Past/Present Clients
I have consulted for numerous groups, including Can-Am Care, Numera|Social, 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.

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