```xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns3:query_definition xmlns:ns2="http://www.i2b2.org/xsd/cell/crc/psm/1.1/" xmlns:ns4="http://www.i2b2.org/xsd/cell/crc/psm/analysisdefinition/1.1/" xmlns:ns3="http://www.i2b2.org/xsd/cell/crc/psm/querydefinition/1.1/">
    <query_name>Diabetes mellit@17:01:55</query_name>
    <query_timing>ANY</query_timing>
    <specificity_scale>0</specificity_scale>
    <panel>
        <panel_number>1</panel_number>
        <panel_timing>ANY</panel_timing>
        <panel_accuracy_scale>100</panel_accuracy_scale>
        <invert>0</invert>
        <total_item_occurrences>1</total_item_occurrences>
        <item>
            <hlevel>4</hlevel>
            <item_name>Diabetes mellitus</item_name>
            <item_key>\\i2b2_DIAG\i2b2\Diagnoses\Endocrine disorders (240-259)\Other endocrine gland diseases (250-259)\(250) Diabetes mellitus\</item_key>
            <item_icon>FA</item_icon>
            <tooltip>Diagnoses \ Endocrine disorders \ Other endocrine gland diseases \ Diabetes mellitus</tooltip>
            <class>ENC</class>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
</ns3:query_definition>

```

I want to find patients who have been diagnosed with diabetes mellitus at any point in time, regardless of the specificity or accuracy scale, and the query should be applied to the first panel of the analysis with a total of one item occurrence. The query will specifically look for the International Classification of Diseases (ICD) code 250, which represents diabetes mellitus, within the Endocrine disorders section of the diagnoses category.