Is a 1 year enough to learn german in an institution and be eligible to pass the language entrance exam for medical studies in a university ?( I will try to do my best and I will spend all the day on practicing german )
this is a question that can't be answered in a general way. Too many parameters are playing a role. In any case, this is a really ambitious goal.
For further information see tinyurl.com/j3todun (especially last section of the text). There are a few medicine schools in Germany where you can study medicine in English (e.g. tinyurl.com/zb5c4k7).