Our results are also in line with other previous studies that reported that insulin therapy and diabetic complications were associated with a poorer QoL in patients with T2DM (Bradley & Speight, 2002; Collins et al., 2009; Depablos-Velasco et al., 2014; Shim et al., 2012; Speight & Bradley, 2000; Sundaram et al., 2007); however, in a longitudinal study of patients with T2DM starting insulin therapy, QoL improved six months after the commencement of insulin therapy (Wilson, Moore & Lunt, 2004). This evidence concerns the gene INS and type 2 diabetes mellitus.