Taking medication: “I had never heard of the need to homogenize the neutral protamine hagedorn (NPH) insulin 20 times before use” (Mother of a T1DM teenager and 38-year-old man with T1DM for 20 years and advanced retinopathy); “I did not know different insulins had different peaks and time durations... I thought they were all the same” (mother of a 25-year-old man diagnosed with T1DM for 13 years); “I did not know we should check needle flow before using (the insulin pen) and to not inject cold insulin” (mother of a 17-year-old girl with T1DM for 5 years). This evidence concerns the gene INS and type 1 diabetes mellitus.