Properly diabetes mellitus, it is a disease characterised by high blood sugar levels and sugar in the urine. Diabetes is really several disorders, generally broken down into juvenile onset and adult onset. The first, currently called insulin-dependent diabetes mellitus (IDDM or Type I), is somewhat hereditary, and results from inadequate synthesis of native insulin or sometimes from auto-immunity or a virus, and occurs most frequently in tissue-types HLA, DR3, and DR4. These folks tend to be lean. The other main group is known as non-insulin-dependent diabetes mellitus (NIDDM or Type II). It is caused by a combination of heredity, constitution, and lifestyle, where high blood sugar and high blood fats often occur at the same time, and where hyperglycemic episodes have continued for so many years that fuel-engorged cells start to refuse glucose, and the person is termed insulin resistant. These folks are usually overweight, tend to have fatty plaques in their arteries, and usually have chunky parents.