Is there a "Type 3 Diabetes"? Well, maybe…
The "official" descriptions of various varieties of diabetes mellitus as promulgated by the American Diabetes Association are in a position statement titled Diagnosis and Classification of Diabetes Mellitus. They list type 1 (previously referred to as insulin-dependent diabetes or juvenile-onset diabetes), which is usually due to autoimmune destruction of the Î²-cells of the pancreas, and type 2 (non-insulin-dependent diabetes or adult-onset diabetes), with both insulin resistance and insulin deficiency. They go on to list other varieties of diabetes, but none of them were deemed worthy of having a name that includes "Type whatever number is next."
This has led to an interesting situation: on the Internet, one can find that various people have christened various varying disorders as "Type 3 Diabetes" (T3DM). None of which are official, of course:
Several years ago, there was a push to label Alzheimer’s disease as T3DM. For example, there is a publication Alzheimer’s Disease Is Type 3 Diabetes-Evidence Reviewed where the authors opined "We conclude that the term "˜type 3 diabetes’ accurately reflects the fact that AD represents a form of diabetes that selectively involves the brain and has molecular and biochemical features that overlap with both type 1 diabetes mellitus and T2DM." Well, that’s one opinion. Another opinion on whether Alzheimer’s should be labeled T3DM: "There is no justification for classifying Alzheimer’s disease or any of other diseases mentioned above as type 3 diabetes mellitus."
Some authors seem to want to persuade the ADA that they should add more types, and these authors proceed to choose which types of diabetes should have which numbers assigned. For instance, a listing at a dental website () adds type 3 (defined by the author as related to hormonal disorders) and type 4 (defined by the author as gestational diabetes) to the list. I really have no understanding why ADA quit at two types, rather than adding more, but this author’s opinion that what ADA calls "Other specific types of diabetes: endocrinopathies" and "Gestational diabetes mellitus" should be type 3 and 4, rather than GDM being 3 and hormonal cause being 4, is a coin toss.
Another interesting discussion mentioning T3DM turns out to simply be a typo. "lifestyle changes [were] more effective with a 58 percent reduction in progression to T3DM." This statement was part of a review of the results of the Diabetes Prevention Program, which was a study that evaluated methods of prevention of T2DM, and which never mentioned T3DM.
My personal favorite definition for type 3 diabetes is at Diabetapedia. The Diabetapedia definition is "A person who cares for an individual with diabetes. Examples: family member, close friend." Along the same lines, a tweeter at Twitter calls himself "@Type3Diabetes" and explains that he is a "T1 diabetes husband, which makes me a T3."
So it’s open season on naming Type 3 Diabetes - whatever you want to call T3DM is okay, but it’s as Charles Dodgson pointed out in Through the Looking-Glass, and What Alice Found There, “When I use a word,” Humpty Dumpty said, in a rather scornful tone, “it means just what I choose it to mean - neither more nor less.”