16586
Overall , serum TB12 fell more between randomization and 36 weeks gestation in the metformin group than in the insulin group ( metformin : - 19 . 7 +/- 4 . 7 pmol / l , insulin : - 6 . 4 +/- 3 . 6 pmol / l , p = 0 . 004 ) .
 Chemical: metformin; Chemical: metformin
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: metformin; Chemical: metformin