Question about post-exercise basal

[Darryl]

This question is follow up to my earlier post about post-exercise BG levels.

moco89 explained very well how during exercise,
muscles can take glucose out of the blood without insulin,
which is why BG can go low. My question now is what is
the best way to respond the low BG's that occur after
exercise.

Our daughter engages only in mild exercise but still we
have seen the effects of BG staying on the low side for the
rest of the day and through the night. Sometimes to the
point where we can even shut off her basal and maintain
good BG.

We were advised at the hospital to reduce or stop basal
after exercise to avoid lows. I have also read this same
advice in other places.

It doesn't make sense to me to reduce basal. It seems
like a convenient way to control blood sugar, but not what
the body really needs.

If I understand correctly, muscles need more glucose both
during and for a period of time after exercise. The muscles
deplete glucose from the blood, causing BG to decrease. If
this is treated by decreasing or stopping basal, then the
muscles get the glucose they need, but the other cells in
the body would be deprived of glucose.

Therefore, it seems to me that treating post-exercise lows
by reducing or stopping basal could lead to metabolism
problems in general, and ketoacidosis in particular, even
if BG's are in normal range.

Wouldn't the best course of treatment for post-exercise
lows be to leave basal at the normal level and provide
additional carbs? I know that this does not sound all that
easy to do (especially overnight). But the alternative of
cutting basal, while convenient, sounds like it's not in the
best interest of the body.

I am not diabetic, but my daughter is. If I exercise a lot,
I need more carbs all day, and I think she does too. Can
anyone elaborate on this?

[D-Dad]

I agree with you. It sounds like some nice low GI foods with some protein would be good.... nuts, cheese stick, a banana (which has little protein but a green one is low GI).

[moco89]

The body replenishes the glycogen stores (glucose stored in muscle/liver) after exercise.....You would actually need more carbs, rather than less, to prevent less hypoglycemia btw.

This is from gssi web (gatorade sports science institute), in an article specifically about diabetes and athletes. I didn't just pull this up randomly, I've read it before :). I don't necessarily agree w/ all of the info, but it is very informative....you can also search gssiweb for "diabetes"

http://www.gssiweb.com/Article_Detail.aspx?articleid=622

The postexercise resynthesis of glycogen, the storage form of glucose in the muscle and liver is slower in people with diabetes (Hermansen, 1980). Thus, these athletes may not be completely glycogen-restored before the next practice or game. Another documented concern is delayed hypoglycemia. This phenomenon can occur for from 4–48 hours after exercise (MacDonald, 1987). Delayed hypoglycemia that occurs at night can disturb sleep, which could contribute to prolonged fatigue during the training season.

(At the bottom of the Page).....

What is the Optimal Time of Day for Exercise?
Disturbances in blood glucose are less likely if exercise is performed in the morning before breakfast and before the morning administration of insulin. This is because circulating insulin is low at this time, and if a regular meal was consumed the night before, both liver and muscle glycogen stores should be filled.

What Should Be Done Before Exercise?

1. Measure blood glucose concentration to determine how well it is under control.

* If blood glucose is <5 mM (90 mg/dl), extra carbohydrate before exercise will likely be required.
* If blood glucose is 5–15 mM (90–270 mg/dl), extra carbohydrate may not be required.
* If blood glucose is >15 mM (270 mg/dl), delay exercise and measure urine ketones.

a. If urine ketones are negative, exercise can be performed, and extra carbohydrate is not required.
b. If urine ketones are positive, take insulin and delay exercise until ketones are negative.

2. Determine the appropriate pre-exercise carbohydrate meal.

Before exercise one can estimate the intensity, duration, and the energy requirement of the exercise by consulting standard tables. By dividing the estimated calorie requirement by four (each gram of carbohydrate is equivalent to four calories), the potential carbohydrate requirement in grams can be predicted. Diabetics should eat or drink an appropriate carbohydrate-containing snack or meal 1–3 h prior to exercise. This food or beverage should contain about 15 g of carbohydrate per 30 min of anticipated moderate-intensity exercise. Foods such as fig bars, crackers, yogurt, muffins, oatmeal cookies, soups, dried fruit, bread sticks, and granola bars are appropriate. Drinks that contain simple carbohydrates and electrolytes are excellent for helping avoid hypoglycemia and plasma volume depletion during exercise (for example, an 8-oz serving of Gatorade contains 14 G of carbohydrate). Even whole milk, skim milk, and orange juice are better than water alone On the other hand, meal replacement drinks designed to provide complete supplementation, i.e., carbohydrate, fat and protein, can lead to an inappropriate rise in blood glucose during and after exercise.

3. Administer the appropriate pre-exercise insulin dose.

* Inject insulin (or adjust the output of an insulin pump) about 1 hour before exercise.
* Decrease the dose of insulin so that the greatest increase in circulating insulin does not occurs during the exercise period.
* Do not use an arm or leg that will be involved in exercise as an injection site and be sure that the insulin is injected into subcutaneous tissue not muscle.

What Should Be Done During Exercise?

1. Monitor blood glucose during long exercise sessions. For running, cycling, swimming and other endurance types of activities, this may require setting a circular course so that glucose meters are periodically available.

2. Always replace fluid losses adequately. The goal should be to replace all or nearly all of the body weight lost as sweat during the exercise period itself. This weight loss can be estimated by recording the difference in body weight before and after exercise on prior occasions.

3. If required, use supplemental carbohydrate feedings (an additional 40–50 g for adults, 20–30 g for children) every 60 min during extended periods of moderate intensity exercise. For example, Gatorade restores blood glucose very rapidly during exercise in people with Type 1 DM who are becoming hypoglycemic. Other sports drinks with a similar composition (~6% carbohydrate plus electrolytes) may also be effective but have not been studied.

What Should Be Done After Exercise?

1. Monitor blood glucose, including overnight monitoring if exercise is not habitual and/or is performed in the late afternoon. Avoid alcohol consumption after exercise because alcohol diminishes the ability to monitor marked or subtle feelings that would otherwise alert the person with diabetes to the fact that blood glucose is either too high or too low.

2. Adjust insulin administration downward to decrease immediate and delayed actions of insulin. If required, increase carbohydrate intake for up to 24 hours after activity, depending on the intensity and duration of exercise (more intense and prolonged exercise requires more carbohydrate) and the risk—based on prior experience— of the occurrence of low blood glucose. Ingestion of ~1.5 g carbohydrate/kg body weigh (0.7 g/lb) soon after exercise will help restore muscle and liver glycogen after very prolonged or exhausting exercise. It should be noted, however, that although low blood glucose can occasionally occur several hours after exercise in diabetics, some insulin is needed late after exercise to fully restore muscle glycogen levels.

3. Ingest the appropriate amount of carbohydrate on a daily basis.

The type of exercise—endurance, sprint, resistance, intensity of exercise—high, medium, low, and duration of exercise—brief, moderate, prolonged—(or as in most sports some combination of these) must be considered:

* If aerobic exercise of a moderate intensity is to be undertaken on a daily basis and usually lasts less than 1 hour, the diabetic athlete should ingest 5–6 g of carbohydrate/kg body weight (2.3–2.7 g/lb) on a daily basis.
* If the athlete trains more than 1–2 hours per day, 6–8 g of carbohydrate/kg body weight (2.7–3.6 g/lb) may be required daily.

Which is Worse, Low Blood Glucose (Hypoglycemia) or High Blood Glucose (Hyperglycemia)?

The answer is that both hypoglycemia and hyperglycemia should be avoided whenever possible. For athletic competitions, hypoglycemia must be avoided because fatigue, loss of mental focus, and reductions in strength are obviously not compatible with athletic success. Thus, it may seem reasonable that maintaining a state of hyperglycemia is one way to insure athletic success. In the short run this may work, but the consistent state of hyperglycemia must be avoided because even mild but consistent hyperglycemia significantly increases the likelihood of serious medical complications of diabetes. Unfortunately, some diabetic athletes apparently sacrifice glucose control in favor of avoiding hypoglycemia so they can perform at high levels.

Other Practical Considerations

Here are some additional tips for the diabetic exerciser:

* Frequent glucose monitoring is obviously essential for safe exercise.
* Carry some form of carbohydrate snack (simple sugars).
* Carry medical identification.
* If convenient, exercise with a friend who knows you have diabetes. Carry a cell phone in case of a diabetic emergency.
* Invest in good footgear if walking, jogging, and/or running are among your chosen activities.
* Use extra care to avoid large fluctuations in plasma glucose when exercising in the cold or heat.

SUGGESTED ADDITIONAL RESOURCES

American Diabetes Association (2002). Clinical Practice Recommendations: 2002. Diabetes Care 25 (suppl. 1):S64–S68.

Peirce, N.S. (1999). Diabetes and exercise. Br. J. Sports Med. 33:161–173.

N.B. Ruderman, J.T. Devlin, S.H. Schneider, and A. Kriska (eds.) Handbook of Exercise in Diabetes. Alexandria, VA: American Diabetes Association.

[hypercarmona]

3. Administer the appropriate pre-exercise insulin dose.

* Inject insulin (or adjust the output of an insulin pump) about 1 hour before exercise.
* Decrease the dose of insulin so that the greatest increase in circulating insulin does not occurs during the exercise period.
* Do not use an arm or leg that will be involved in exercise as an injection site and be sure that the insulin is injected into subcutaneous tissue not muscle.


That is the part that gets tricky.


The only time I asked for "help" from my prior CDE about exercise, her advice was to eat a 15 gram carbo snack, take a bolus for it and then exercise immediately, which would have put me in the hospital. What works in theory often doesn't work so well in practice when it comes to diabetes. So I tried to find something that works for me, even though it might not be textbook. My strategy is this: I cut back on the carbs for which I bolus at meals, way back. I don't like taking more than 1 unit at a time (18 grams of carbo for me) when I am expecting heavy exercise or walking outside in the heat. I wait at least 3 hours after my last bolus (unless it's an all day event), then add what I would normally eat at the meal to my unbolused daily carb amount as frequent snacks during and after the exercise, and as an additional bedtime snack. (So that means I'm eating roughly the same amount of carbo, but I'm just spreading it out throughout the day a little more thinly.) I've got less circulating insulin from boluses, but since my Lantus is static and unadjustable (I can't adjust what I've already taken;)), I've still got some circulating insulin. It helped me during four days of walking at Busch Gardens Williamsburg in 90 degree heat, no lows.

I recommend the Diabetic Athlete (even though it's kind of outdated) and Pumping Insulin books. They're both really good resources to use as a jumping off point in finding what works for your daughter.

[twodoor2]

* If blood glucose is <5 mM (90 mg/dl), extra carbohydrate before exercise will likely be required.
* If blood glucose is 5–15 mM (90–270 mg/dl), extra carbohydrate may not be required.
* If blood glucose is >15 mM (270 mg/dl), delay exercise and measure urine ketones.



I wanted to isolate this part of Monica's quote because I think it's extremely helpful, and I live by this type chart when DD's very active.

[Darryl]

... her advice was to eat a 15 gram carbo snack, take a bolus for it and then exercise immediately, which would have put me in the hospital.

Could you tell me more about this? What exactly would happen if you ate and bolused right before exercise?