There is another thread about this question:

https://www.researchgate.net/post/is_it_possible_to_use_skin_patch_for_insulin_delivery_in_diabetic_people

Insulin is a macromolecule so naturally it can't pass through skin. But researchers are working on techniques to let it pass.

Here Are some articles that may help you:

http://link.springer.com/article/10.1023%2FA%3A1015869420159?LI=true

http://onlinelibrary.wiley.com/doi/10.1002/jbm.a.35869/full

http://www.tandfonline.com/doi/abs/10.3109/10717544.2016.1155243

https://ecommons.cornell.edu/handle/1813/43906

http://link.springer.com/article/10.1023/B:PHAM.0000029282.44140.2e

Dear Neda

Check out this:

http://www.diabeticadvocate.com/2013/04/insulin-cannot-be-absorbed-through-skin.html