UniCamillus;
Saint Camillus International University of Health Sciences;
Rome 00131;
Italy;
Diabetes Research Institute Federation(DRIF);
Division of Endocrinology and Diabetes;
CTO Alesini Hospital;
Department of Systems Medicine;
University of Rome Tor Vergata;
Rome 00145;
Italy;
Network of Immunity in Infection;
Malignancy and Autoimmunity(NIIMA);
Universal Scientific Education and Research Network(USERN);
Rome 00145;
Italy;
Department of Human Sciences and Promotion of the Quality of Life;
San Raffaele Roma Open University;
Rome 00166;
Italy;
Laboratory of Cardiovascular Endocrinology;
IRCCS San Raffaele Pisana;
Rome 00166;
Italy;
Metformin; Vitamin B12 deficiency; Metformin-induced cobalamin deficiency; Diabetes; Type 2 diabetes; Prediabetes; Screening criteria; Neuropathy; Anemia;