Numerous studies have shown that microneedles can be used for transdermal delivery of metformin [72], lidocaine [73], insulin [74], vaccines [17], human growth hormone (hGH) [75] and nanoparticles (NP) [76] (Figure 7) in the treatment of wounds (acne) [77], diabetes therapy [23], tumors [78] and so on. The gene discussed is INS; the disease is diabetes mellitus.