23401
A total of 5608 patients who were on antidiabetic monotherapy for at least 1 year before adding a second agent to their medication regimen between October 2001 and September 2008 participated in this study .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None