How to get the Excel fields(double) as int

I am trying to read the uploaded Excel content, but the following two methods cannot use reader.GetInt32(1):

1. I set the Excel field as "common format" and then input a number 1. --> Show InvalidCastException

2. I set the Excel field as "integer format" and then input a number 1. --> Show InvalidCastException

So I confirm the Excel field type, and found out it was a double.

var fieldType = reader.GetFieldType(1);

I have two question:

1. Is this a setting of Excel itself which causes my get type is a Double?

2. How to get the Excel fields as int in my case? Because the content of the fields I should insert into the database must be int.