Depending on how you want to map your fields, you may need to modify data types of fields so that they are compatible with the data types used in the field you selected to map to. The update from the map to the desktop application uses ODBC and is more forgiving of data types than the update from the desktop application to the geodatabase, which uses ArcSDE. ArcSDE strictly controls updates with data types. If data is pushed to the geodatabase with the wrong data type, the ArcSDE update will most likely fail. To determine whether or not a data type change is required you may need to test with the existing data type to see if updates are successful both from the map and from the desktop application.