DNA insertion sequences near the insulin gene affect glucose regulation

There is restriction-fragment length polymorphism in the 5'-flanking region of the insulin gene on the short arm of chromosome 11 in man. The polymorphic DNA sequences in 53 members of a large family were analysed by means of the restriction endonuclease BglI. In this family, the BglI restriction fragments were found in four sizes--2.8 kilobases (kb), 2.9 kb, 4.6 kb, and 4.8 kb. They segregated as alleles. The two larger BglI restriction fragments (U alleles) were associated with high haemoglobin Alc levels in both blood-related and unrelated non-diabetic members of the family.