Craig E. Taplin, MDDivision of Endocrinology and Diabetes

Seattle Children’s Hospital

1. Review some basic assumptions about exercising with T1DM

2. How much should those with T1DM exercise, and are those guidelines being followed?

3. How does T1DM affect physical fitness?4. How does physical activity affect HbA1c?5. How does physical activity affect cardiovascular

risk factors in T1DM?6. Why does exercise cause high and low blood

sugars?7. How can that be prevented/treated?

Exercise is good for T1DM◦ It’s fun!

◦ Improves cardiovascular health

◦ Weight control

◦ Help maintain healthy blood pressure

◦ Improves cholesterol profile

◦ Good way to handle stress

◦ It is often outside - vitamin D

“… participate daily in 60 minutes or more of moderate to vigorous physical activity…”

Same effect on blood sugar???

So, youth with type 1 diabetes exercise at least as much as their non-diabetic peers.

This is a huge success story in and of itself!

But… Is physical fitness affected by T1DM in children? And does T1DM affect physical fitness?

What does recent data tell us?

Copyright restrictions may apply.

Herbst, A. et al. Arch Pediatr Adolesc Med 2006;160:573-577.

Is exercise associated with HbA1c in youth?

1-2 x week>2 x week

19,143 patients

2012 UK study - 60 young people with T1DM, mean age 12.5 years, mean HbA1c 8.4% and 37 controls (siblings)

•no difference in fitness at baseline•no difference in degree of physical activity

Moderate–vigorous physical activity(but not fitness) predicted1/3 of the variance in HbA1c, even when accounting for confounding variables such as insulin dose, age, weight, puberty stage…

What about the other way around…

◦ What is the effect of type 1 diabetes on fitness and exercise performance?

“Eurofit physical fitness test”◦ Nine tests- motor and cardiorespiratory fitness tests (VO2

max estimated by shuttle run test)**

◦ Performed by PE teachers

◦ Between 8am and 10am

◦ BGL had to be between 90-180 mg/dL** not validated as a measure in T1DM

106 youth with T1DM, 130 controls◦ Mean HbA1c 8.2-8.9% (depending on group)

T1DM group just as active as the controls

Decreased fitness (VO2 max) in girls and pubertal boys with T1DM c/w controls

In those without diabetes:◦ ↑age, skinfold thickness, ↓physical activity and female sex

were all associated with ↓VO2 max

In those with diabetes◦ All of the above, plus ↑HbA1c associated with ↓VO2 max

What about the other way around?

In multiple regression, VO2 max was the only predictor of ↓ HbA1c.

Adult (trained) athletes

◦ A1c <7% were as fit or fitter than those without T1DM

◦ A1c>7% less fit

High blood sugars

Decreased physical fitness

??

Or…

This is not at all clear, as most data is cross-sectional

Perhaps we should consider cardiovascular health as well as HbA1c when considering the data on physical activity and exercise?

What does that data tell us?

Influence of Physical Activity on Vascular Health

Diabetes, Obesity and MetabolismVolume 13, Issue 4, pages 382-384, 23 FEB 2011 DOI: 10.1111/j.1463-1326.2011.01361.xhttp://onlinelibrary.wiley.com/doi/10.1111/j.1463-1326.2011.01361.x/full#f1

Adult (trained) athletes

◦ A1c <7% no cardiac dysfunction c/w controls

◦ A1c>7% decreased cardiac function

Diabetes Care, October 2012

Mean HbA1c 8.7%T1DM for 6 years

What else might be going on to explain these findings?

Nadeau K et al, JCEM 2010

Insulin resistance predicted exercise performance in T1DMNadeau K et al, JCEM 2010

Fit

ter

Insulin sensitivity

Children with T1DM exercise as much as their non-diabetic counterparts

◦ this is a huge success story in and of itself

The data is mixed on whether children with T1DM have overall reduced fitness-and it may be time spent exercising as much as absolute fitness that matters

The higher the HbA1c, the poorer the physical fitness (does not prove causality)

We do not have good data on acute performance and glycemia

Does a fitness program improve HbA1c?

◦ The jury is out but in cross sectional studies fitness, or activity, predicts HbA1c

Children with T1DM who are less active have an adverse cardiovascular profile◦ … but those who are active may not

Training can improve fitness in T1DM and vascular health

Children with T1DM appear to be insulin resistant – this may be a critical link to pursue

“I think the worst thing imaginable is to get really low and pass out”

Jay Cutler, NFL quarterback

Denver Broncos, Chicago Bears

Resistance versus Aerobic

High Intensity vs low intensity

Early vs Late effects

12 adults, mean HbA1c 7.1%

45 minutes of weight lifting or 45 minutes of cardio on treadmill

Diabetes Care 2013;36:537-542

Higher sugars during and

immediately after resistance

exercise

Maximal session, or Intense Intervals, induce more of:◦ Adrenaline◦ Noradrenaline◦ Growth Hormone◦ Cortisol

This has been shown to be preserved in people with T1D

Together, these hormones cause glucose to rise (or stay the same) by increasing glucose output from liver, and making the body resistant to insulin◦ The effect is short lived, though…

Diabetes Care 2013, Davey et al

So:1. Aerobic exercise at submaximal effort causes a slow and

steady drop in blood sugar2. Intense exercise such as all out efforts, or intervals, or

resistance (weights) doesn’t have the same effect, and may raise blood sugar acutely

3. But there is still a risk later on of a low blood sugar (overnight)

Frequent specific factor in etiology of severe hypoglycemia is exercise, particularly aerobic exercise◦ Bhatia, Wolfsdorf Pediatrics 1991 – exercise caused 71% of episodes◦ Davis, Jones et al, Diabetes Care 1997 – 75% of events occurred at night

and most were related to increased activitiy

Fear of hypoglycemia is significant barrier to exercise in T1DM.◦ Diab Care 2008 2109-9, Ped Diab 2007 362-8

*** The unifying management goal in T1DM is the lowest possible HbA1c for that individual patient WITHOUT excessive hypoglycemia

For 130 lb. person; 15 grams of CHO every…

Cycling: 15 minutesSoccer: 10 minutesBasketball: 10 minutesRunning: 10 minutesWalking: 30 minutes

To maintain a steady blood glucose…

ISPAD Guidelines

Diabetes Care. 2006 Oct;29(10):2200-4.

75

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2 PM 4 PM 6 PM 8 PM 10 PM 12 AM 2 AM 4 AM 6 AM

Me

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Glu

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(m

g/d

L)

Sedentary day

Exercise day

Overnight glucose levels after

afternoon exercise

Exercise Period

4:00 – 5:15 PMmean BGL 154

28% had lows

mean BGL 131

48% had lows

Impact of exercise on overnight glycemic control in children with type 1 diabetes mellitus. J Pediatr. 2005 Oct;147(4):528-34.

Midday Exercise in Adolescents – higher risk for low sugars for the next 11 hours

45 minutes cycling at 95% lactate threshold starting at noon

11pm

20 grams of glucose more was needed for the hour of exercise, and 2-3 grams more per hour up until 11 hours later

Midday bought of exercise – 45 minutes at 95% lactate threshold

Remember the duration of action of rapid acting insulin – 3 to 4 hours

Try and minimize peaking boluses during exercise◦ Peak is at 90 minutes

Eat early enough so you can bolus to help fill energy stores

Eating within 2 hours of exercise may require a bolus reduction, and/or basal reduction

Eating afterward may require a bolus reduction

Adjusting post-exercise meal bolus- how much?

Diabetes Care 2013 Campbell et al

Full bolus

50% bolus

75% bolus

“Hypo” unawareness is common in children

Antecedent exercise and antecedent hypoglycemia are known risk factors (Cryer, Diab Care 2008)

Hypoglycemia on nights following exercise:

◦ peripheral glucose utilization is increased by exercise

◦ counterregulatory hormone responses are impaired by sleep

◦ insulin concentrations are unchanged because of the treatment regimen (but could be)

Tamborlane W, JCEM 2007

1. Address the increased insulin sensitivity Reduce the insulin (easier with pumps)

2. Address the autonomic failure to counterregulate Give medications that ↑ glucose

3. Eat more food/snacks? perhaps counterproductive (weight)

increased glucose requirement occurs later in the night

not very effective in adult studies

Overnight Blood Glucose Measurements

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21:00

22:30

23:30

0:30

1:30

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'

Terbutaline

Basal Reduction

Control

For some, ceasing the pump during exercise may be sufficient to prevent a nocturnal event

An overnight basal rate reduction◦ physiologically logical, sensible and safe◦ Some high sugars undesirable

What to recommend for those not on a pump?

Predictive alarms and closed loop systems?

Diagrammatic representation of clinical study procedures.

Sherr J L et al. Dia Care 2013;36:2909-2914

Copyright © 2011 American Diabetes Association, Inc.

Episodes of overnight treatable hypoglycemia (reference blood glucose <60 mg/dL) during

OL and CL.

Sherr J L et al. Dia Care 2013;36:2909-2914

Copyright © 2011 American Diabetes Association, Inc.

A: Overnight insulin delivery in units/h 7–11 h postexercise (10:00 p.m. to 2:00 a.m.), with CL

associated with lower insulin delivery (P = 0.008).

Sherr J L et al. Dia Care 2013;36:2909-2914

Copyright © 2011 American Diabetes Association, Inc.

Different Kinds of Exercise do Different Things to Blood Sugars acutely◦ But all increase risk of lows many hours later

Consider pump suspension during exercise as one option to prevent lows (and/or basal rate reduction beforehand)◦ But beware of highs if this is done with intense or interval exercise!

Consider minimizing the amount of rapid acting insulin on board during exercise and then snack to maintain sugar level

Beware of hormonal responses (excitement/nerves) that might quickly wane (highs followed by lows)

Consider decreasing the post-meal bolus, and also night time insulin to prevent night time low blood sugars (this is what the artificial pancreas seems to do

Check blood glucose often – this is the best management strategy of all!

“If only exercise for children with diabetes could just be child’s play”

Editorial, Journal of Pediatrics, Nov 2010 (Laffel L)

Thank you.