Hi, if your bg is high and your control is generally poor you are more prone to get skin infections, including boils, but non diabetics can get boils too, the armpits are a common site, and adolsecents often get them too, they are basically infected hair follicles.
Make sure your bg is not high, wash daily with antiseptic soap and dab with something like TCP antiseptic, this will help with the pain and kill the infection too.
Or another very tried and tested remedy is to mash up an onion, apply it to the boil and it will help bring it to a head and it will discharge itself, but never ever squeeze it.
If you get fever, or nauseous or other symptoms or if they are getting worse get them checked by your doctor or nurse, normally with antiseptic soap and antiseptic cream or liquid or the onion mash, they get better quickly.
I hope you are better soon.
Karen