This study will investigate the efficacy of a combination treatment of duloxetine +
pregabalin compared with the maximal dose of each drug in monotherapy, in patients with
diabetic peripheral neuropathic pain (DPNP) who have not responded to the standard
recommended dose of either drug. It will provide an answer to a common clinical question,
namely, is it better to increase the dose of the current monotherapy or to combine both
treatments early on, in patients who do not respond to standard doses of duloxetine or
pregabalin.