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

### Input Text: Diabetes of 2 months duration resulted in decreases in body weight and increases in fluid consumption , urine volume , frequency of micturition , and average volume per micturition ; effects which were prevented by insulin treatment .
### Output Text:
Diabetes of 2 months duration resulted in decreases in body weight and increases in fluid consumption , urine volume , frequency of micturition , and average volume per micturition ; effects which were prevented by insulin treatment . 