A prospective study on the development of type 2 diabetes in normoglycaemic offspring of couples who both had type 2 diabetes showed defects in glucose disposal and insulin sensitivity, that is, more than 10 years before the development of diabetes, participants who developed the disease had lower values compared to controls of both SI ([3.2 ± 2.4 vs. 8.1 ± 6.7] ×10-3·min-1·pmol-1 insulin; P < 0.0001) and SG ([1.6 ± 0.9 vs. 2.3 ± 1.2] × 10-2·min-1; P < 0.0001) [14]. The gene discussed is INS; the disease is type 2 diabetes mellitus.