Insulin-like growth factor-binding protein 3 receptor (IGFBP-3R) agonists and methods of their use to treat diseases involving IGFBP-3 and IGFBP-3R are provided. The agonists may be antibodies or other molecules specific for binding to and activating IGFBP-3R. The agonists are used to treat e.g. cancer, metabolic syndrome and obstructive respiratory disorders. In addition, methods of diagnosing cancer and predicting the chance of recurrence, metastasis and/or survival by measuring the level of IGFBP-3R in tumor tissue are provided.
