There's now a kotlin.jdbc package available (see the kotlin.jdbc package in the API docs) which has some extension functions for working with JDBC.
Its in no way finshed but you can see the kinds of things possible in this test case. The kotlin-jdbc API lets you use functions to be able to properly pool Connections / Statements and handle ResultSets properly without worrying about manual cleanup code etc. You can also iterate through result sets directly with a for loop and use index based or name based access into result sets etc.