Prevalence of beta allele of the insulin gene in type II diabetes mellitus.

Fifty-two patients and 36 controls were compared in a search for insulin gene variants among type II diabetic patients with fasting hyperinsulinemia (above 90 microU/ml) and a fasting C-peptide to insulin molar ratio between 1.11 and 1.50. Alpha and beta alleles of the insulin gene were characterized by restriction analysis of polymerase chain reaction (PCR) products and direct sequencing. The more frequent occurrence of the alpha allele of the insulin gene within the control population as compared with a prevalence of the beta allele in the diabetic patients (P, 0.05) was observed. The beta allele, usually described as the rare allele, seems to be associated with the disease.