Insulin-treated type 2 diabetes patients with coexistent thyroid dysfunctions (n = 328) were divided into three groups according to their sequence of diagnoses when known (140 patients could not be classified resulting in 188 patients for following analyses): 133 (70.7%) had thyroid disease diagnosed after diabetes onset (group 3) whereas less patients developed thyroid diseases prior to (group 1; n = 46; 24.5%) or within the same year (group 2; n = 9; 4.8%) of diabetes onset. This evidence concerns the gene INS and thyroiditis.