The present invention provides a method of treating insulin-dependent diabetes mellitus in a subject, comprising administering to the subject a therapeutically effective amount of a Janus kinase inhibitor, or a pharmaceutically acceptable salt or ester thereof, or a therapeutically effective amount of intravenous immunoglobulin, or a therapeutically effective amount of a therapeutic agent that destroys B lymphocytes, or a combination thereof. The present invention also provides kits containing the same.