The reason is unknown, and since this syndrome occurs almost entirely in third world countries, research on this form of diabetes is nearly nonexistent. A catchall for forms not covered by the types described above. These terms are not used entirely consistently. Some doctors will refer to any diabetic using insulin as type 1, and will refer to the early onset of type 1 diabetes as type 2 until insulin therapy is required. The situation is complicated by the fact that early in the course of the disease it can be difficult to determine which type is occuring, especially for patients in their 30's, the age when the onset of both types is common.
Different patients respond very differently to what is categorized above as the same disease.
The root causes of all forms of diabetes are not understood, and are likely more complex and varied than the simple categories show. Type 1 diabetes likely has a few root causes, and type 2 diabetes probably has a larger number of root causes. There are also well documented reports of cases of diabetes with unexplained combinations of syndromes from types 1 and 2. The classification above is not completely standard, and other classifications exist. This probably reflects the fact that type 1 diabetes is harder to ignore, and that type 2 seldom strikes the younger people who are more likely to have net access.