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From North Carolina, USA:

I'm on the swim team at my high school. It's my second year on it and I just now started having problems with my blood sugars. For some reason, my sugar goes high during practice and afterwards and I usually have moderate or high ketones afterwards. I thought exercise usually causes low book sugar, not high. I was told when I first was diagnosed not to exercise if I have ketones, but what if I seem to get them each time? I was just wondering what could be causing my high sugar since I thought exercise usually caused low blood sugar, if anything. I disconnect my pump while swimming. It's for two hours.


Blood sugars can go high during or after exercise due to lack of insulin, increased hormone secretion (i.e., adrenaline, cortisol, growth hormone) or a combination of the two. The guideline for going without insulin (in this case removing the pump) is about one hour. Typically, when the pump is off for more than an hour, one's blood sugar starts to rise. If this were the case, it would be prudent to check blood sugars at the one hour mark after taking off the pump to see if a supplemental bolus of insulin is needed. The problem with this technique is that the lack of insulin during exercise may not show up as a high blood sugar until hours afterwards. I would recommend keeping the pump on, going to the temporary basal and setting it for 0% which means no insulin is being given. Set the duration for one hour so the pump will automatically come back on without having to do anything. It the pump is not waterproof (only a couple are), hooking back up to give insulin lost will be the only option for swimmers.

The reason for hormones to increase suddenly may be due to adolescence, mental stress from the event, or physical stress (i.e., an increase in the intensity or duration). If a high blood sugar comes down after getting into the exercise, no action should be taken. If not, insulin may be needed and remember always hydrate to help bring blood sugars down.


Original posting 17 Dec 2006
Posted to Hyperglycemia and DKA and Exercise and Sports


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