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From Lombard, Illinois, USA:

Lately, I have found that my blood sugar levels go up a lot of the time when I exercise. There are many times when I have had insulin and they do drop low. However, I teach dance and have found that they will jump up so much as I work out and teach. For example, today, I started out at 90 mg/dl [5.0 mmol/L] then, about two hours later, it jumped to 147 mg/dl [8.1 mmol/L], then, two hours after that, it was 268 mg/dl [14.9 mmol/L]. The only thing I had was water.

Please help me! I am worried that this is not right for my body to be doing that. The doctors and nurses just look at me strangely and say that it is weird and shouldn't happen. I saw that there were a few other people who have written you about this. I am wondering first, if this is more normal that everyone is making it to be, and secondly, how I should treat it. Should I give myself some insulin to prevent this from happening? Is there something I should be eating or doing beforehand to keep that more under control?


Many people with type 1 diabetes experience high blood sugars when they exercise or compete in their sport. This situation often frustrates athletes as well as the recreational exercise enthusiast. There are a couple of possibilities why this happens. If an insufficient amount of insulin is in the blood, the blood sugar will rise. Adding exercise to the mix, especially anaerobic type of activities such as weight lifting, sprinting, or any sport requiring short intense spurts can cause a further increase in blood sugar. The low insulin levels joined with the secretion of hormones (i.e., epinephrine, norepinephrine, cortisol, growth hormone, and glucagon) cause the liver to release glucose into the blood sending blood sugar even higher. These hormones are called "stress" hormones and have the same affect on the body whether it is a physical stress, like exercise, or a mental one, which can occur prior to an important athletic competition. Athletes who are very competitive often struggle to deal with this situation.

There is no easy solution to combat high blood sugars before, during, or even after exercise since each person's diabetes is individualized. There are techniques to try to help minimize the increase. For instance, as long as the healthcare team approves, insulin may be used prior to the activity if levels are too high to start. It is recommended to be conservative with this approach since exercise and insulin can cause a rapid drop in blood sugar causing levels to go too low. If one unit of insulin usually drops the blood sugar 50 mg/dl [2.8 mmol/L], try one-half of a unit figuring on the same 50 mg/dl [2.8 mmol/L] drop. The only way to determine the right amount of insulin to use is to check blood sugars more often and look for patterns rather than just one attempt. If high blood sugar is a problem during the event, give the insulin about 30 minutes prior to the start to give it time to work.

Another suggestion is to drink water when blood sugars are high. This helps in a couple of ways. It helps lower blood sugars and washes away ketones if they are present. It also helps hydrate the body, which is often dehydrated due to high blood sugars. During strenuous exercise, the blood sugar may rise merely due to dehydration. In this case, simply drinking water will help return levels to normal without using insulin. Whether you have diabetes or not, staying hydrated will help performance, especially in the last part of games when fatigue plays a significant role in winning or losing. A good rule to follow is to drink two glasses (16 ounces) two hours prior to activity, one glass (eight ounces) a half hour to an hour before and 4 to 6 ounces every 15 to 20 minutes during activity.


Original posting 3 Oct 2006
Posted to Hyperglycemia and DKA and Exercise and Sports


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Last Updated: Tuesday April 06, 2010 15:10:10
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