There is, in fact, no difference in meaning between preventive and preventative. Some, including William Safire in a 1993 On Language column, have suggested using preventive as an adjective and preventative as a noun, but both forms of the word have alternated freely as adjective and noun since they entered the language in the 17th century. Despite their introduction into English at roughly the same time (the Oxford English Dictionary dates preventive back to 1626 and preventative to 1655), preventive has won out as the preferred version.
Family or personal history. Your risk increases if you have prediabetes — a precursor to type 2 diabetes — or if a close family member, such as a parent or sibling, has type 2 diabetes. You're also at greater risk if you had gestational diabetes during a previous pregnancy, if you delivered a very large baby or if you had an unexplained stillbirth.