GIGYF1 loss of function (N = 64 carriers) was associated with higher susceptibility to T2D (OR = 6.10 [3.51–10.61], p = 1.8 × 10−12) and higher acute and longer-term average levels of glycemia in non-diabetic individuals (random glucose p = 2.6 × 10−5 and HbA1c p = 6.6 × 10−7). The gene discussed is GIGYF1; the disease is type 2 diabetes mellitus.