Smoking habits and painful diabetic neuropathy.
In order to assess the relationship between chronic painful diabetic neuropathy and current--or lifetime--smoking habits, the smoking history of 49 diabetic patients was investigated and compared with that of 23 diabetic patients without chronic pain (age 51.0 +/- 1.9 years, mean +/- SEM). Current level of nicotine intake was measured using urinary cotinine (a nicotine metabolite), and expressed as cotinine/creatinine ratio (COT/Cr), and lifetime smoking load by pack years (20 cigarettes per day for 1 year equals 1 pack year). Current pain intensity was evaluated using a visual analogue scale (VAS). The presence of chronic painful diabetic neuropathy was based on clinical history and examination. Of those patients with painful neuropathy, 26% were current smokers (age 54.2 +/- 3.2 years, mean +/- SEM), 31% ex-smokers (age 57.0 +/- 2.9 years), and 43% lifelong nonsmokers (age 58.0 +/- 2.9 years). Pain duration and intensity were similar in all three groups. COT/Cr levels were similar in current diabetic smokers with pain [5.0 (0.2-10.6) micrograms/mg] and the diabetic control group of smokers without pain [6.8 (1.8-13.3) micrograms/mg, NS]. There was no relationship between VAS and either COT/Cr levels or pack years in current smokers, or between duration of pain and pack years in diabetic current or ex-smokers. In conclusion, we found no relationship between current or previous levels of smoking and severity or duration of chronic painful diabetic neuropathy.