In the sentence extracted from biomedical literature, identify all the disease entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="disease"> to denote a disease.

### Input Text: In the Caucasian population , it has been demonstrated that the insulin gene ( INS ) region contains the insulin - dependent diabetes mellitus locus ( IDDM2 ) .
### Output Text:
In the Caucasian population , it has been demonstrated that the insulin gene ( INS ) region contains the <span class="disease">insulin - dependent diabetes mellitus</span> locus ( IDDM2 ) . 