What are the uses of heparin for someone with diabetes?

None. Heparin is a blood thinner. Has no use for diabetes directly. It is used however in hospital settings since diabetics are at higher risk for forming dvts.
Prevent clots. Heparin is a blood thinner, and is usually used to prevent or treat blood clots, particularly during hospitalization, but also while waiting for the levels of Coumadin (warfarin) (an oral anti-coagulant) to become therapeutic.