Various sources have defined "type 3 diabetes" as, among others, gestational diabetes, insulin-resistant type 1 diabetes (or "double diabetes"), type 2 diabetes which bankrupt progressed to cause injected insulin, and latent autoimmune diabetes of adults (or LADA or "type 1.5" diabetes.) There is also maturity onset diabetes of the boyish (MODY) which is a batch of several distinguished gene (monogenic) disorders with strong family histories that present as type 2 diabetes before 30 years of age.

Both type 1 and type 2 diabetes are at least partly inherited. There is a genetic element in individual susceptibility to some of these triggers which has been traced to particular HLA genotypes (i.e., the genetic "self" identifiers relied upon by the immune click here system). However, even in those who have inherited the susceptibility, type 1 diabetes mellitus seems to desire an environmental trigger. A minute proportion of people with type 1 diabetes carry a mutated gene that causes maturity onset diabetes of the girlish (MODY).