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From McAllen, Texas, USA:

I am a 47 year old male who has had type 1 diabetes for 22 years and wears a pump. I am doing well with control except during my exercise times (I jog for generally about 30 minutes at 10 MPH pace). I disconnect the pump prior to the exercise, try to have blood sugars at 130 mg/dl [7.2 mmol/L] or so and also eat 30 grams of carb one half hour prior to the exercise, but my blood sugar tests in the 40s or 50s [mg/dl; 2.2 or 2.8 mmol/L] after the exercise and then will often rise without additional food -- sometimes too high. How can I level out these lows and prevent the highs following exercise?


You have a number of options available to you in managing exercise blood sugars on an insulin pump. Monitoring and blood sugar patterning will assist you and your diabetes team in deciding which of these suggestions work best for you.

Your lows immediately after exercise are most likely due to some remaining circulating basal insulin during exercise, despite your choice to disconnect the pump while running. You may wish to attempt to address this by decreasing your basal rate, suspending, or even disconnecting one half-hour to an hour or more before exercise. By doing so, you will have very little circulating insulin during exercise (similar to what a normally functioning pancreas would do), and will hopefully avoid the hypoglycemia. In addition, this should decrease your need for supplemental carbohydrate prior to exercise. You might also consider reducing the bolus at the meal prior to exercise if it is within two to three hours prior to your run time.

The lows you are experiencing certainly may be playing a role in the elevated blood sugars you are seeing after exercise (a rebound hyperglycemia effect related to liver glycogen release in an effort to raise your blood sugar). By avoiding the lows, you may have less difficulty with post exercise highs. If you continue to see post exercise highs despite the pre-exercise adjustments, recognize that high intensity exercise produces glucose-raising hormones such as cortisol, epinephrine, and glucagon. This may require increased circulating insulin post exercise (perhaps via a higher temporary basal rate). In this situation some pump users find success by reducing or suspending for exercise, but also ingesting a carb snack of 15-30 grams just before exercise, with a "partial bolus" (50% or less of normal insulin coverage). The carb provides immediate glucose and works to prevent hypoglycemia during exercise, while the partial bolus provides circulating insulin which seems to prevent the hormonal driven rises in blood sugar post exercise.

Discuss these options with your diabetes team and let us know how it goes! Here's wishing you best of success with your exercise plans!


Original posting 5 Jun 2001
Posted to Exercise and Sports and Insulin Pumps


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