Diabetes Central

So, why is living and running with diabetes difficult?

When our body makes insulin, tiny adjustments happen in split-second time intervals – insulin can be pumped into the bloodstream very quickly and then shut off just as quickly.  With this finely tuned system, a person is not aware of very tiny fluctuations in the amount of glucose (sugar) in his/her bloodstream and the person rarely suffers from high or low blood sugars.

When a person has to inject insulin, the system no longer works in a finely tuned, rapid manner.  The person with diabetes has to estimate how much insulin they will need and then must wait out the length of time that the insulin is working.  Depending on the type of insulin, it can become active in 15 minutes to one hour (the insulin your body makes starts to work in less than one second).  And, the insulin can stay active for 2 hours to 20 hours (your body can make insulin activity stop in less than one second). 

So, this difference in times of injected insulin’s activity creates HUGE problems for the person with diabetes.  What if the person injects insulin but then his/her meal is delayed?  Big problem – blood sugar starts dropping and the insulin is already in the bloodstream.  This kind of problem is very dangerous for the person on insulin.  What if he/she did not inject enough insulin?  The person may not know for two hours and then will have to inject more insulin to correct the high blood sugar (and have several more hours of insulin in their system).

So, why does the length of time for which injected insulin stays active matter? Insulin makes glucose (sugar) leave the bloodstream and enter our cells – the more insulin, the more sugar out of the bloodstream (and the faster it goes, too).  The ratio of insulin to blood sugar is not straightforward – our bodies are more sensitive to insulin in the afternoon and much more sensitive when we are active or exercising.

If the person with diabetes injects enough insulin to eat a sandwich and chips, but then has to get up and walk two miles across campus before the insulin has finished working, he/she may not have enough sugar in the bloodstream to accommodate for the extra activity.  So, not only does the amount of insulin need to be estimated, but the activity for the next two to three hours has to be estimated.  On the other hand, if activity is assumed and then something intervenes, the person must take extra insulin and extend his/her planning of activity for another two to three hours from the correction shot.

The complexity of planning around insulin and food becomes even more frustrating when we factor in the “background” or basal insulin.  Basal insulin is a type of insulin that works for many hours to keep a person’s body functioning at his/her base metabolic rate.  But, even this insulin dosing has to factor in estimates of daily activity, amount of sleep, weather, time of month for women, illness or fatigue, and the list goes on.

In addition, the amounts of insulin that cause these kinds of variation can be as small a drop as a pinhead – and the insulin is drawn up in a syringe that does not allow for such minute dosing (but the person who uses an insulin pump CAN make those tiny measurements!).  The layers of calculations and dosing go deeper, but this gives a general picture of the pitfalls and dangers. 


How does Missy balance running and diabetes?

An 8-part series that was posted on the website for The Diabetes Exercise and Sports Association (DESA).


Some of Missy's Favorite Links

Missy Foy