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: METHODS : This was a multicenter , randomized , open - label study in adult smokers with heart disease , hypertension not controlled by medication , and / or diabetes mellitus .
### Output Text:
METHODS : This was a multicenter , randomized , open - label study in adult smokers with heart disease , hypertension not controlled by medication , and / or diabetes mellitus . 