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From Minnetonka, Minnesota, USA:

My 14 year old son has had type 1 for three years. He plays defense in soccer on a premier team. Three times, during a tournament, he plays great the first game (8:00 a.m.), but before the second game (1:00 p.m.), he will experience a low blood sugar. We start by giving him 15 grams of carbohydrates, re-check his blood sugar in 15 minutes. This will go on two to four times of eating/re-checking to we get his level high enough to play (above 150 mg/dl [8.3 mmol/L]). He then becomes shaky and his vision becomes blurry, too blurry to go into the game. He is unable to read jersey numbers or see the ball. At the last tournament, he went in shortly after the second half started and said he felt like he was in a Fun House of Mirrors. We have been told that the change in sugar levels from low to high can cause water to swell the lens in the eye causing the blurry vision. So, how can we prevent the lows before the game? We normally reduce the basal to two to three hours at 50%. Is there anything else we can try or give him to eat to maintain a normal range?


An increase in blood sugar above normal can cause changes in the lens of the eye, typically described in terms of lens swelling. Lens swelling typically causes a shift towards nearsightedness, causing distance objects to become blurry. I am not aware of any scaled correlation between the level of elevated blood sugar and the level of blur, that could be used to predict the amount of induced nearsightedness. When you say that you try to raise his blood sugar above 150 mg/dl [8.3 mmol/L], I am assuming only slightly above 150 mg/dl [8.3 mmol/L]. With that relatively "small" increase above normal, I am surprised your son feels his vision is "too blurry to go into the game." This leads me to wonder what his baseline visual status is.

I recommend your son have his vision tested at a time when his blood sugars have been in a stable normal range for a week, if possible, to determine his baseline visual status. Perhaps his vision is less than standard 20/20 to begin with, but "passable," and with the increase in blood sugar, the added vision change is enough to push him "over" and then he is uncomfortable to continue play.

If one or both parents are nearsighted, it would not be unusual that one of your children may begins to show nearsightedness between the ages of 12 to 14.


[Editor's comment: For advice on how to avoid exercise induced hypoglycemia, see our previous questions on Exercise and Sports and review our Sports Corner web page. You did not specify when you reduce his basal rates. You might want to consider reducing them before the first game and perhaps for a longer time frame. Your son may also need to make sure he eats complex carbohydrates and protein for breakfast before the first game. Please consult your diabetes team about the specific times and rate of reduction you should consider. They should also be able to offer advice about what foods to eat. BH]

Original posting 6 Jun 2006
Posted to Hypoglycemia and Exercise and Sports


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