My two year old has symptoms of diabetes, including extreme thirst and constant urination. She is drinking between 20 and 30 eight ounce cups a day and soaking through her diaper. She had a urine test done, but it came back normal. The doctor tested for diabetes, but it was negative. Did the doctor only test for diabetes mellitus or diabetes insipidus, too? I know that both have similar symptoms. Is there a regulation that you test for both types when testing for diabetes or just diabetes mellitus? Her urine is really dilute and colorless. Should I pursue this and ask to check her for diabetes insipidus?

Your daughter also needs a better screening test for diabetes mellitus than a simple urine dipstick test, preferably a fasting serum glucose or a one hour glucose tolerance test (I use the one hour test rather than a two hour when I suspect type 1; I’ve found the two hours screens better for type 2). Frequently, when the urine is so dilute from such high volumes, the sugar can be negative on a dipstick urinalysis.

MSB
Additional comments from Dr. David Schwartz:
While I agree with Dr. Brown that a better assessment needs to be done to help exclude diabetes mellitus (DM), a “very dilute and colorless” urine is not so typical of diabetes mellitus.

It is, however, very typical of diabetes insipidus (DI).

No, there is no regulation to require simultaneous assessment for DM and DI. Perhaps too often, DI is not thought of as it is not too common in otherwise, seemingly neurologically healthy children. If your doctor performed a formal urinalysis (to include assessment of the urine concentration – often called “urine specific gravity”, then there was some screening done for DI. If the doctor ONLY checked for glucose in the urine, then DI was not screened for.

A first morning urine sample with a concurrent basic chemistry (all preceded by about 6-8 hours of NOTHING to drink/eat the night before) can really better focus a diagnosis of DI. Sometimes, a formal fluid deprivation challenge is required and a referral to a pediatric endocrinologist would be in order.

DS