In previous studies, having family members with type 2 diabetes has increased the risk of developing type 1 diabetes [3–8], and is associated, for example, with later onset of type 1 diabetes, higher rate of the metabolic syndrome, a metabolic profile related to insulin resistance in patients with type 1 diabetes (e.g. higher BMI, larger waist circumference, higher triacylglycerols, decreased insulin sensitivity and higher HbA1c concentrations) and greater risk for diabetic complications [15, 16, 18, 21–23]. Here, INS is linked to type 2 diabetes mellitus.