Additional support to the hypothesis that environmental changes affect intermittent, but not persistent carriage is the observation that DPP4 inhibitors, a diabetes therapy with known immunomodulatory properties, but not any other medication for the treatment of diabetes not only altered the significant association between increasing %HbA1c and risk for intermittent carriage in the primary cohort but also is itself a risk factor for intermittent carriage (71, –, 73). Here, DPP4 is linked to diabetes mellitus.