I am on Cymbalta 60mg and Lyrica 75mg. From what I've read on Cymbalta and Lyrica are used for diabetic PNP although I am idopathic. Here's the info on from the prescription guide (good info in the prescription guide):

Peripheral Neuropathic Pain — The recommended dose for Cymbalta is 60 mg administered once daily. There is no evidence that doses higher than 60 mg confer additional significant benefit and the higher dose is clearly less well tolerated.

The maximum recommended dose of LYRICA is 100 mg three times a day (300 mg/day) in patients with creatinine clearance of at least 60 mL/min. Although LYRICA was also studied at 600 mg/day, there is no evidence that this dose confers additional significant benefit and this dose was less well tolerated.

I'm on less Lyrica because the fact I also take Cymbalta. For me Neurotin did not work at all. Cymbalta worked for awhile and now I'm not sure if it is no longer working or the pain just got a lot worse and I'd be in severe pain without it. The doc added Lyrica and that helped a little but I'm still getting worse. She finally said, "I don't know what to do with you. I don't want to give you anymore medication" I asked my neurologist for a referral to pain management. Because I'm not that far away she referred me to the Johns Hopkins pain treatment center. Took 6 weeks for next available appointment. I go in a little over a week.