Recently, Spencer et al. published their interesting article in Influenza and Other Respiratory Viruses providing evidence that there is no impact of diabetes status on immunogenicity of trivalent inactivated influenza vaccine in older adults. Although we agree with the conclusion, we suggest that the transportation condition of the serum samples should be added in the description of serological surveys of influenza in the future. Stability of specific influenza antibodies in sera samples stored in differing conditions should be considered.