Type 1 Diabetic Athletes: Nutrition Part II

Consuming carbs within 30 minutes after exhaustive, glycogen-depleting exercise allows your muscles to more rapidly restore their glycogen and may actually prevent late-onset hypoglycemia that can occur up to 24 hours after exercise. Insulin sensitivity is generally heightened immediately after exercise, and during this time, your body’s blood glucose uptake into muscle to reform glycogen can be accomplished with minimal amounts of insulin circulating around. Good glycemic control during the post-exercise recovery period is essential to subsequent exercise performance, though, since you may experience reduced rates of net muscle glycogen repletion if your diabetes is poorly controlled during that time. To maintain glycemic control, you will probably need to take some additional insulin to cover the carbs that you eat post-exercise, albeit generally less than your usual doses.

Guidelines for Fluid and Carbohydrate Ingestion for Physical Activity

• Consume adequate fluids before, during and following exercise to help prevent dehydration during exercise, particularly when hyperglycemic
• During hot weather, consume sports drinks containing electrolytes during exercise lasting longer than 60-90 minutes; otherwise consume cool water unless additional carbohydrate is needed to treat or prevent hypoglycemia

Carbohydrate before Exercise
• Carbohydrate intake a few hours before exercise generally benefits endurance capacity when taken along with adequate insulin
• Ingestion of extra carbohydrate prior to exercise is recommended if blood glucose levels are <100 mg/dl (5.5mM), but only if you can't or won't lower your insulin levels
• Avoid food with a high fiber or fat content before (and during) exercise

Carbohydrate during Exercise
• During exercise lasting more than 45 minutes, use a carbohydrate drink or snack to avoid low blood glucose and to improve exercise tolerance
• Consume about 10-15 grams of carbohydrate every 15-30 minutes during activity, modified for each athlete based on insulin regimen and exercise type

Carbohydrate after Exercise
• Following exercise, modest amounts of carbohydrate (along with insulin, as needed) should be ingested to minimize the risk of later-onset hypoglycemia
• Post-exercise carbohydrate needs will vary depending upon blood glucose levels and how many carbs you took in during the activity

In summary, athletes who have diabetes and wish to optimize their athletic performance need to have a greater understanding of exercise factors, such as the effects of circulating insulin levels on exercise responses, physiological response to different types of activities and training, and nutritional concerns specific to the diabetic athlete. While a greater knowledge of these concepts provides a starting point for optimizing performance, effective exercise can only be achieved by athletes individually working to determine their own, unique glycemic responses. You’ll need to engage in frequent blood glucose monitoring (i.e., before, during, and after exercise), just like competitive diabetic athletes with well-established exercise routines do until you establish your own patterns and learn how to make adjustments to stay in control of your blood sugars.

For more information about participation of diabetic exercisers in a variety of sports and recreational physical activity (along with real-life athlete examples), please consult The Diabetic Athlete: Prescriptions for Exercise and Sports (Human Kinetics, 2001) by Sheri Colberg. A fully revised and expanded version of this book will be available in November 2008 titled “The Diabetic Athlete’s Handbook.”


8 thoughts on “Type 1 Diabetic Athletes: Nutrition Part II

  1. Anne

    Hi Sheri,
    Thanks for these great posts on type 1. I’ve been perplexed by the rule of eating immediately post-exercise because the muscles supposedly take up glucose better with less insulin. While this is true for me when I am first doing a new workout (such as my first really long bike ride in a while), if the exercise is more routine for me, I have to take my normal dose of insulin. Overall, my insulin sensitivity increases, but not particularly right after exercise. I do take considerably less insulin during the exercise, as long as my blood sugar is not high to start out with, though.


  2. Mark

    Thanks, Sheri — I just experienced may first middle-of-the-night lowish spot (only down to 3.9, but for me as a Type 2, this is a level I only reach with extreme exercise). I race-walked 16 km yesterday in under 2 hours and then strolled another 7 km later on in the day, eating low-carb meals to minimize my post-prandial spikes. But clearly I did not eat substantially enough throughout the evening, because in the middle of the night I went lower that I’ve yet seen.
    I’m eagerly awaiting your sequence on Type 2 athlete nutrition, Sheri — especially for folks like me who have a lowish level of insulin production as measured by low C-peptide levels.

  3. Greg

    Hi Sherri,
    I’m a Type 1 and I’ve used your book “The Diabetic Athlete” in training for triathlons. THANK YOU for writing this book. After a two year layoff from exercise, I’m working out again and finding it hard to shed the 25 pounds I’ve gained.. I’ve been working out for about 3 months now. Perhaps I’m getting older and my metabolism is changing (I’m 39 now).

    My question is this: How do I ensure that I’m fueling my recovering muscles without eating a lot of food? I’ve lowered my post workout basal rate which controls my blood sugar. However, I still get really hungry and end up eating more food than I’d like. Should I just know that i’ll be hungry while losing weight?

  4. Sheri Colberg, PhD

    Thanks for the comments about my first book. Just to let you know, a fully expanded and revised version of that book now called “The Diabetic Athlete’s Handbook” is being released in November 2008. I’m sure that will be helpful to you as well.
    As for your issues with losing weight, changes in metabolism are mainly due to losses of muscle mass. As you start to gain some more muscle from exercising consistently, you may not find that it has changed that much in just two years. In any case, you do need some carbs to properly refuel, but try to keep the overall levels of insulin that you have to take as low as possible to help with your weight loss. It’s virtually impossible to lose much weight if you’re having to take high doses of insulin. Focus more on increasing your intake of quality protein sources (e.g., egg whites, lean meats, fish, and soy) and moderate your intake of carbs. You won’t go hungry doing that, either.
    Good luck with it. Sheri

  5. Anonymous

    Looking forward to the new book.

    I’ve been using the recommended strategy for about 2 weeks now and have lost about 4 pounds! I’ve been focusing on eating carbs immediately following my workout . Then for the rest of the day, I switch to more proteins. and vegetables. Only 21 poiunds left to get back into racing shape! Thanks again for the advice!


  6. Katie Aldridge

    Hi Sheri,

    I’ve been using your book “The Diabetic Athlete” for about a year now, and I am so glad to find this blog!

    I am Type 1, age 26, and I recently started a video exercise program called P90X. It’s a combination of cardio, flexibility, and strength training, and each workout is about an hour.

    I started doing the workouts at about 6:00 a.m. because I was getting low blood sugar when I worked out in the afternoon/evening. However, now I’m getting super high blood sugars in the morning! For about 3 hours during and after exercise, I’m having to do almost 200% the amount of basal insulin that I need the rest of the day. I know this is because of morning hormones (cortisol? adrenaline?), but I want to know if there’s a way to decrease my morning insulin resistance. I want to lose a little bit of weight, and I worry that having so much insulin in my system in the morning will work against that.

    Should I just work out in the afternoon and try to prevent the blood sugar lows?

    Thank you for any help you can give me! -Katie

  7. shericolberg Post author

    There are a couple of ways to approach your problem. One is simply to eat a small amount and give some rapid-acting insulin (albeit less than normal) to cover it BEFORE you start doing intense work first thing in the morning. That effectively breaks your fast and reduces cortisol levels, which are what cause insulin resistance in the morning.
    If you work out in the afternoon instead, try lowering the basal for a period of time BEFORE you start your workout (1-2 hours) and then keep it lower afterwards for a while. You’ll have to experiment with that one to figure out how much to lower it beforehand and afterwards, based on your body and your food intake.
    Sheri Colberg, PhD


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