It was observed that countries (mostly Scandinavian) with higher consumptions of T1D “enhancing” antibiotics, e.g., tetracycline (J01A) and narrow-spectrum penicillin (J01CE, J01CF), experience a higher prevalence of T1D, along with the low consumption of “inhibitor” antibiotics, e.g., broad-spectrum, beta-lactamase-resistant, combination penicillin (J01CR) and other broad-spectrum antibiotics (macrolides or quinolone). Here, LACTB is linked to type 1 diabetes mellitus.