Primary efficacy measure of this 13-week randomized clinical trial of pregabalin 600 mg/d (BID) as treatment of painful DPN was endpoint (EP) mean pain score (MPS) on an 11-point numeric rating scale (NRS) derived from patients' daily pain diaries. Secondary efficacy measures included weekly MPS and EP and weekly sleep-interference scores (on an 11-point NRS). Primary safety endpoints were amplitude and conduction velocity for 4 nerves (median-motor, median-sensory, ulnar-sensory, and peroneal-motor) assessed at baseline (BL), EP, and 2-week follow-up. 82 patients were randomized to pregabalin, 85 to placebo (PBO). After 1-week dose escalation, pregabalin patients received 600 mg/d for 12 weeks. EP MPS was significantly lower in pregabalin treated patients than in PBO-treated patients (mean difference, - 1.28; P=.0003). Significant pain improvement among pregabalin patients was evident at Week 1 and every weekly timepoint thereafter. Pregabalin was statistically significantly superior to PBO for reducing pain-related sleep-interference score at every weekly timepoint (except Weeks 9,10) and at EP (mean difference, - 1.08; P=.0019). No statistically significant differences in amplitude or velocity were observed for any of the 4 nerves tested. In an open-label (OL) extension of this trial, patients received 150-600 mg/d pregabalin (BID), adjusted to optimize efficacy and tolerability, for up to 6 months. 97% of patients received dosages of ≥300 mg/d. Pregabalin was generally well tolerated, with 70/104 patients completing 24 weeks of treatment. 15 patients (14%) withdrew from OL treatment because of AEs. Peripheral edema, dizziness, and somnolence were the most common AEs associated with treatment. In conclusion, pregabalin 600 mg/d (BID) showed robust and sustained efficacy in pain improvement with no meaningful effect on nerve conduction during 13 weeks of double-blind treatment. Pregabalin was generally well tolerated during both 13-week double-blind and 6-month OL treatment. [ABSTRACT FROM AUTHOR]