Low incidence of type 1 diabetes in Iran.

There is a worldwide increase in the incidence of type 1 diabetes (1–3). This increase, in conjunction with the lack of complete concordance in monozygotic twin pairs, points to the importance of environmental factors (3). Useful clues about these environmental factors may be obtained by studying geographical variation in incidence in relation to the characteristics of different countries. There is a paucity of information regarding type 1 diabetes in Iran. It was the purpose of this study to provide some baseline data regarding this disease in Iran. The surveyed area was the southern province of Fars in the 5-year time period between 21 March 1991 and 20 March 1996. The region, which had a population of 3,800,000 in 1996, covers an area of 133,000 km and is the largest province in southern Iran. Of the whole Iranian population, 10% live in southern Iran and 64% are residents of Fars.