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My 25 year old boyfriend was told that he has excess sugar in his urine. Does this mean that he has diabetes? Or may be in a high risk category? I don't know a lot about diabetes, but am just curious as to some questions we may ask when we visit the doctor again? Does anyone have any suggestions? He is being tested again today.


The presence of sugar in the urine usually means diabetes. (Sugar is present in the urine in diabetes because the kidneys fail to hold onto it completely when the sugar level in the blood is very high; the kidneys think sugar is "good stuff" to hold onto, but can't hold onto all of it if the blood level of sugar is above what's called the threshold (about 180 mg/dl, which is well above the expected blood sugar levels of anyone without diabetes); people who don't have diabetes rarely have a sugar above 150 mg/dl (and that only after a huge meal). So most of the time, a positive test for urine sugar implies a high blood sugar, or, in other words, diabetes.

There is a very rare exception: another disorder called renal glycosuria exists, where the kidney's threshold of where it can't hold onto sugar is much lower than the usual 180 mg/dl. In renal glycosuria, if the kidney's threshold is at a level of about 100, it would be expected that the person with the low threshold would routinely have sugar in the urine, since the blood sugar in people without diabetes is frequently about 70-130 or so.

In order to distinguish diabetes from renal glycosuria, it might be necessary to repeatedly measure blood and urine sugar levels. On the other hand, if your boyfriend has a few very high blood sugar levels (well over 140 fasting, or over 200 after eating), he has diabetes, and renal glycosuria is excluded.


Original posting 3 Nov 96


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Last Updated: Tuesday April 06, 2010 15:08:52
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