Sheri R. Colberg, Ph.D. Old Dominion University Norfolk, Virginia Exercise & Busy Kids – Preventing and Managing Hypos Sheri R. Colberg, Ph.D. Old Dominion University Norfolk, Virginia

“Diabetic Athlete” - An Oxymoron? No! There are many diabetic athletes worldwide competing even at elite levels Chris Dudley (NBA basketball) Jay Leeuwenburg (NFL football) Kris Freeman (U.S. XC ski team) Gary Hall, Jr. (Olympic swimming) Many others have run marathons, done triathlons, and competed in every type of sport and physical activity

Goals of Exercise Management Prevention of hypoglycemia during and after any physical activity Rapid management of hypos caused by exercise Prevention of hyperglycemia and DKA Optimal athletic performance

Effects of Low BG on Exercise Early, rapid-onset fatigue Potential loss of coordination Reduced endurance Decreased performance

What Is Optimal BG for Exercise? Varies, but most athletes perform best with BG levels of 80-180 Some start out higher, but few lower

Fuel Use and Acute Effects of Exercise on BG Control

Exercise Energy Systems The way energy is produced and used during an activity affects BG use Three distinct energy systems exist: Immediate (phosphates, or ATP-CP) Lactic acid system (rapid glycolysis) Aerobic (oxygen) Their use is a continuum and depends on exercise type, duration, and intensity

Exercise Energy Systems 10 sec 30 sec 1 min 3 min 5 min

Fuel Use during Exercise For most exercise, carbs are main fuel: glycogen (~80%), BG (20%) Romijn JA, et al., JAP, 88(5): 1707-1714, 2000

Fuel Use during Exercise BG uptake into muscles occurs 2 ways: Insulin-mediated Contraction-induced These two mechanisms act separately, but additively using GLUT4 Thus, active insulin levels affect BG response to exercise by  BG more

Glucose Transport into Muscles Wojtaszewski JF, et al., Acta Physiol Scand, 162(3): 351-8, 1998

Insulin Levels and BG Response If active insulin levels are high, then BG  during extended activity If insulin is deficient and ketones present, BG usually  during exercise Check for ketones if BG>250 mg/dl and has been elevated for a while Exercise if ketones are none, but take corrective insulin (~50%) if >250 mg/dl

Insulin Levels and BG Response DM lacking Insulin DM with Insulin Nondiabetic Controls

Hormones and BG Levels Some insulin is needed to moderate the effects of glucose-raising hormones: Adrenaline and noradrenaline Glucagon, cortisol, and growth hormone Cortisol and GH are higher during morning exercise (insulin resistance) Hormone release is intensity-dependent (more adrenaline at higher workloads)

High Adrenaline Activities  BG Sports w/ intense “bursts” Sprinting of any type Heavy weight lifting Scary activities (e.g.,hang gliding or downhill skiing) Intense competition (mental stress)

Endurance Exercise Effects Extended exercise usually results in  BG levels if any insulin “on board” Pre-exercise, short- or rapid-acting insulin doses will likely need to be lowered BG likely  after activity, with less insulin needed in post-exercise period  insulin action during muscle glycogen repletion

Balancing Exercise Blood Sugars

Exercise Diet Medication Diabetes Therapy

Challenges with Busy Kids Insulin doses and diet must match precisely with exercise to avoid hypos Risk of hypoglycemia is higher both during and following exercise May be no improvement in overall BG control in active kids w/o appropriate changes in diet and/or insulin doses

Regimen Changes for Exercise Increase carbohydrate intake for the activity to prevent hypos Adjust insulin doses before, during, and after activities Try to prevent acute and delayed-onset hypoglycemia, which can occur for up to 48 hours after exercise

Predicting Glycemic Responses Checking BG before, often during, & after exercise is key to learning BG responses BG levels during usual activities can become somewhat predictable & a pattern established

Factors Affecting BG Response Exercise intensity, duration, and type Carbohydrate supplementation Initial blood glucose levels Insulin dose  before and/or during exercise and insulin peak times Training effects on fuel use Timing of exercise bout Other factors affecting BG

Exercise Intensity

Exercise Intensity Competitive events may be shorter, but much more intense than practices Greater release of glucose-raising hormones causes BG to  less Mental stress of competition alone can  levels of hormones as well Extra insulin may be needed after competition to bring blood glucose down

Exercise Duration

Exercise Duration The longer an activity lasts, the greater glucose-lowering effect it can have Rate of muscle glycogen use  with increasing exercise intensity Longer duration at same intensity will result in greater muscle glycogen use Greater glycogen depletion will cause  reliance on BG use

Exercise Type

Exercise Type Aerobic vs. anaerobic activities – is there a metabolic difference? Blood glucose easier to maintain during short, intense exercise Longer duration activities generally necessitate greater regimen changes Increased muscle mass improves insulin sensitivity overall

Intermittent High Intensity Ex 4 second sprints every 2 minutes during 30 min mod (~40%) exercise Guelfi KJ, et al., Diab. Care, 28(6): 1289-1294, 2005

Carbohydrate Intake (Grams) ExerciseDuration Exercise Intensity BG <100 BG 100-150 BG 150-200 BG >200 Low 5-10 0-10 None 30 min Mod. 10-25 10-20 5-15 High 15-35 15-30 5-20 10-15 0-5 60 min 20-50 15-40 10-30 30-45 25-40 20-35 Adapted from Colberg, S. The Diabetic Athlete, 2001

General Snacking Guidelines Begin carb intake prior to exercise to prevent hypos Adjust quantity based on pre-exercise BG levels (none may be needed) Plan on snacking more when active insulin levels are higher Snack hourly during prolonged exercise to provide alternate carbs (besides BG)

Carbs to Prevent & Treat Hypos Best carbs for exercise: glucose tablets or gels, sugary candy, regular soft drinks, sports drinks, diluted juice, skim milk, power bars, pretzels, dry cereal, crackers Do not consume: chocolate, donuts, potato chips, most candy bars, fat-laden cookies, high-fat dairy products, etc.

Carb Intake Examples *Soccer: A pump user drinks sports drinks during practices, consuming 15-30 gm of carbs per hour (insulin ) Weight training: An NPH user eats 15 grams of carbs only if BG  85 to start; another eats a higher-fat bedtime snack Swimming: For an AM swim before any insulin, a Lantus user drinks a regular soda to  his BG to 225 mg/dl

Effect of Active Insulin Levels Exercise Plasma Insulin Liver Glucose Output Muscle Glucose Uptake Resulting Blood Glucose Normal Level Markedly Decreased Above Normal Adapted from Colberg, S. The Diabetic Athlete, 2001

Peak & Action of Various Insulins Rapid-acting insulin analogs (Humalog, Novolog, Apidra): peak in 1-2 hrs Short-acting Regular: 2-3 hrs Intermediate-acting (NPH): peak in 4-6 hrs Long-acting, basal (Lantus, Detemir, UL): mild or no peak

Insulin  for Exercise Timing For pre-meal exercise when insulin levels low, little or no insulin  needed For exercise done 1-2 hours post-meal, short/rapid insulin may need to be  Insulin should be  for exercise done during insulin peak times Basal insulin or pump basal rate may be  prior to and during extended exercise

General Insulin  for Exercise Duration Low Intensity Moderate Intensity High Intensity 30 min None 10-20% 10-30% 60 min 20-40% 30-60% 90 min 15-30% 30-55% 45-75% 120 min 40-70% 60-90% 180 min 75-100% Adapted from Colberg, S. The Diabetic Athlete, 2001

Adjustments by Insulin Type Meal Boluses: Low intensity cardio  25% Moderate cardio  33% High intensity cardio  50% Short/intense  0%, plus bolus afterwards Basal: Pump:  basal rate by 50% starting 1 hr prior, or Reconnect hourly to give 50% of usual basal rate Prior to prolonged ex  injected basal up to 25%

Insulin Reduction Examples *Soccer: A pump user disconnects his pump during practices and  pre-ex meal Humalog by 3 units (carbs ) Weight training: A Lantus user takes no Humalog within 2 hrs of weight training Swimming: During swim team season, a Lantus user decreases her total basal dose by 1/3

Training Effects Training  BG use and  fat use Thus, less muscle glycogen used after 2-3 weeks of training Need to  absolute exercise intensity for same effect

Other Training Adjustments Regular exercise improves BG control by increasing insulin sensitivity Lower insulin doses may be needed overall with consistent training Lesser carbohydrate intake may be needed for the training activity Training effects on BG are specific to the activity (with little carryover)

Timing of Exercise Cortisol and growth hormone higher in AM,  insulin action Similar exercise done later in the day (even post-breakfast)  BG more

Other Factors Poor BG control  insulin action Physical/mental stress can  insulin action Insulin action  during 2nd half of menstrual cycle in teens/women Environmental conditions (hot/cold)

Exercise Precautions

Prevention of Acute Hypoglycemia Hypoglycemia (BG < 65 mg/dl) is the most immediate risk during and after exercise Monitor glucose levels; avoid lows with preventive, corrective regimen changes Access to simple carbs is essential for the rapid treatment of hypos Glucagon emergency kits should also be available, especially for longer activities

Prevention of Delayed-Onset Hypo Most common following long duration or repeated bouts of high-intensity exercise Caused by combination of enhanced insulin action & muscle glycogen repletion May occur up to 24-48 hours afterwards, but 6-12 hours most common May be prevented by  insulin doses and/or  food intake

Prevention of Delayed-Onset Hypo Hernandez JM, et al., Med Sci Sports Exerc, 32(5): 904-910, 2000

10-second Sprint at Exercise End Bussau VA, et al., Diab. Care, 29(3): 601-606, 2006

Other Hypoglycemia Risks Prior hypoglycemia (day before) of 70 mg/dl or less can blunt hormone release during mod ex and  risk of ex hypo Hormonal exercise responses more blunted in males than females Likewise, prior (day before) exercise (prolonged low to moderate) can blunt next day responses to hypoglycemia Galassetti, Sandoval, et al., Diab, AJP, 2004, 2006

Prevention of Hyperglycemia Hyperglycemia can acutely result from intense activities, or it can be worsened if metabolic control is poor before exercise Avoid exercising if fasting glucose levels are >250 mg/dl with ketosis present (indicative of insulin deficiency) Use caution if glucose levels are >300 mg/dl, and no ketosis is present ADA/ACSM Position Statement on Diabetes Mellitus and Exercise, Diab. Care, 27(1): S58-62, 2004

Prevention of Dehydration

Prevention of Dehydration Hyperglycemia  risk, but 1-2% of body fluids already lost when thirsty Dehydration can  BG readings as well ( blood volume  BG concentration) Hydrate with cool, plain water before & during activities, but don’t overdo it I full mouthful = about 1 oz. of fluid Use diluted fruit juices or sports drinks

Keys to Optimal Performance

Keys to Optimal Performance Glycemic balance at all times is key to optimizing exercise performance Monitor blood glucose frequently Make diet and/or insulin changes to keep BG as close to normal as possible

Keys to Optimal Performance Consume extra rapidly-absorbed carbs during exercise to prevent hypoglycemia Low BG causes early fatigue and poor performance Elevated insulin levels during exercise  risk

Keys to Optimal Performance Consume carbs for 2-3 hours post-exercise to rapidly restore muscle glycogen Take extra insulin as needed to cover rise in BG levels Glycogen repletion  risk of delayed-onset hypoglycemia

Keys to Optimal Performance Consume adequate fluids to prevent and correct dehydration (esp. if hyperglycemic) Dehydration  performance Elevated BG  risk of dehydration Dehydration can also  BG readings

Keys to Optimal Performance Increase muscle mass to minimize insulin needs overall Muscle acts as a glucose “sink” Lower insulin requirements leave less room for error in insulin doses

Conclusions

Exercise Your Right to Be Active High level, even elite/Olympic, athletic endeavors are possible w/ type 1 diabetes Diabetic exercisers must be in good control of BG levels to perform optimally Balancing carbohydrate intake with exercise use is key to maintain BG control Insulin doses usually have to be lowered for prolonged or frequent training as well

Gold Medal Dreams Are Still Possible With Type 1 Diabetes!

More Activity-Specific Information Sheri Colberg, PhD Human Kinetics (Champaign, IL) 2001 (261 pages) Over 85 sports and activities included www.SheriColberg.com