ABSTRACT. The human insulin gene has been localized to the short arm of chromosome 11. The length of a segment of DNA associated with the human insulin gene is polymorphic. In patients with non-insulin-dependent diabetes mellitus (NIDDM) the proportion of subjects homozygous for DNA restriction fragments of a large size class (U alleles) in the polymorphic region was significantly higher than in normal controls. The U allele is thus associated with at least one type of NIDDM. The U-alleles were also strongly associated with macroangiopathy in diabetic as well as in non-diabetic subjects. Key words: DNA polymorphism, chromosome 11, genetic marker, human insulin gene, non-insulin-dependent diabetes, glucose regulation, atherosclerosis, macroangiopathy.