Aim Microneedles (MNs) create micropunctures and deliver drugs or nutrients deep into skin layer. We demonstrated that MNs, coated with electrosprayed nanoparticles loaded with functional molecules, are useful for transdermal delivery. Methods Electrospraying was utilised to generate drug-loaded nanoparticles and to create uniform coating on MNs. Process parameters and release kinetics were evaluatedin vitro.Thein vivoefficacy of insulin-coated MNs was investigated using diabetic rats. Results Electrosprayed micro/nanoparticles loaded with dye or insulin were coated on MNs with particle size of 515 +/- 286 and 522 +/- 261 nm, respectively. Optimally coated MNs resulted in >70% transfer rate into porcine skins. Insulin-coated MNs were applied to diabetic rats resulting in reduction of blood glucose levels fluctuations, compared to subcutaneous injections. Conclusions Electrospraying is shown to be an effective method to coat MNs with drug-loaded nanoparticles. Coated MNs provide a promising platform for cosmetic, drug and protein delivery applications.