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Biguanides such as metformin are widely used worldwide for the treatment of type - 2 diabetes .
 Chemical: Biguanides; Chemical: metformin
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: Biguanides, metformin 
Answer:
 Chemical: Biguanides; Chemical: metformin