Hi welcome to the health care magic Secondary infection as a result of diabetes here can lead fever.. By travelling he might suffers from viral cold and that can also lead fever with chills Your father s work up done with... -CBC along with platelet count and DC -Auscultation -Physical examination and detail drug history -Peripheral smear examination esp for malaria parasites If specific cause revealed than treatment done for that If fever not resolving and keep on increasing than blood culture like investigation might done until than symptomatic management done, and for fever paracetamol given Advise : Consult physician for examination...