Age and diabetes risk

IDDM can develop at any age, although onset is more common at puberty. There is another (small) peak during midlife. More cases occur during late fall or early winter than any other season, wrote Atkinson and Maclaren. Susceptibility is inherited; the primary gene associated with IDDM is the major histocompatibility complex on chromosome 6, a region associated with genes for the immune system recognition molecules referred to as HLA. In the United States, IDDM is 20 times as common in white persons with HLA types DR3 and DR4 as in the general population. Another gene for IDDM susceptibility has been found on chromosome 11 near the genes for insulin and insulin- like growth factor. There are also 20 other chromosomal regions associated with IDDM predisposition. IDDM is about three times as likely to develop in children whose fathers have IDDM as in those whose mothers have the disease. Not all persons with a genetic susceptibility get the disease: among identical twins, one twin may have IDDM and the other not. The viral model of IDDM explains this discordance; exposure to the pathogen is necessary for triggering the autoimmune attack, and not all persons will "catch" a virus, even when exposed to infected family members.
Atkinson MA, Maclaren NK. N Engl J Med.