1. 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

2. “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

3. 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

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

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

6. Fuel Use and Acute Effects of Exercise on BG Control

7. 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

8. Exercise Energy Systems
10 sec 30 sec min min min

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

10. 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

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

12. 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

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

14. 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)

15. 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)

16. 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

17. Balancing Exercise Blood Sugars

18. Exercise
Diet Medication
Diabetes
Therapy

19. 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

20. 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

21. 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

22. 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

23. Exercise Intensity

24. 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

25. Exercise Duration

26. 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

27. Exercise Type

28. 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

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

30. Carbohydrate Intake (Grams)
ExerciseDuration
Exercise Intensity
BG <100 BG BG
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

31. 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)

32. 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.

33. Carb Intake Examples
*Soccer: A pump user drinks sports drinks during practices, consuming 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

34. 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

35. 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

36. 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

37. 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

38. 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%

39. 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

40. 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

41. 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)

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

43. 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)

44. Exercise Precautions

45. 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

46. 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 hours afterwards, but 6-12 hours most common
May be prevented by  insulin doses and/or  food intake

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

48. 10-second Sprint at Exercise End
Bussau VA, et al., Diab. Care, 29(3): , 2006

49. 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

50. 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

51. Prevention of Dehydration

52. 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

53. Keys to Optimal Performance

54. 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

55. 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

56. 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

57. 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

58. 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

59. Conclusions

60. 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

61. Gold Medal Dreams Are Still Possible With Type 1 Diabetes!

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