This is a really interesting question. Although we are only presented with Gregor when he has been transformed, and so we never see him before he experiences his metamorphosis, we can infer quite a bit through the text about his previous life.
Note how in the text it appears that Gregor had very little social life - he had no friends from work or elsewhere and he definitely did not have any lovers. Likewise, it is clear that, apart form his sister, he does not have close relationships with his mother and father. Even the relationship with his sister seems to be based on a false assumption, for it turns out that she betrays him. He clearly follows a life characterised by isolation and loneliness even before his transformation. The metamorphosis therefore only exacerbates these characteristics because he cannot communicate and he is kept in his room, locked away from the rest of humanity.
Another aspect that we can identify as being similar is the way that Gregor's life was all about working in a job that he hated for the benefit of his family. When he is transformed, Gregor can hear others and discover their wants, but they are unable to find out what he wants. This is ironic, for Gregor's life seems to have been all about meeting the needs of others whilst his own are forgotten.