The role of nitric oxide in skin blood flow increases due to vibration in healthy adults and adults with type 2 diabetes

Background: We recently demonstrated concomitant increases in skin blood flow and nitric oxide (NO) production in young healthy adults in response to externally applied vibration of the forearm. Research has shown that adults with type 2 diabetes exhibit depressed NO production and vascular responses to NO. We hypothesized that subjects with type 2 diabetes would display lower than normal increases in skin blood flow to externally applied vibration. Research Design and Methods: Therefore, the purpose of this study was to compare 20 male and female, age- and body mass index-matched normal adults and adults with type 2 diabetes in terms of the effects of external vibration of the forearm on skin blood flow and the rate of NO production. Skin blood flow and NO production were measured before vibration, immediately after 5 min of vibration, and 5 min after vibration ceased. Results: Although externally applied vibration significantly increased skin blood flow for both groups (P = 0.0001), those with diabetes had significantly lower (223%; P = 0.003) skin blood flows compared to the healthy older adults (461%). The rate of NO production, expressed as μM NO·flux, also increased significantly in both groups after vibration (healthy group, 374%; diabetes group, 236%) and remained significantly elevated (healthy group, 258%; diabetes group, 177%) for at least 5 min; however, the difference between groups was not significant (P = 0.12). Conclusions: These findings suggest that subjects with diabetes exhibit a lower skin blood flow and lower NO response to externally applied vibration than matched normal subjects. © 2009 Mary Ann Liebert, Inc.