For the group diagnosed aged 31–60 years, all 537 individuals (100%) with type 1 diabetes were being treated with insulin (at a mean of 14 years [95% CI 13–16] after diagnosis), whereas only 1924 (16%) individuals with type 2 diabetes were being treated with insulin (at a mean of 7 years [7–7] after diagnosis; p<0·0001). The gene discussed is INS; the disease is type 1 diabetes mellitus.