INS and type 2 diabetes mellitus: Insulin levels were significantly increased in the T2D with cigarette group compared with the control group (control, 8.21 ± 1.46 μIU/ml; T2D with cigarettes, 14.41 ± 1.74 μIU/ml) and in the T2D with e-cigarette smoking group when compared with the control group (control, 8.21 ± 1.46 μIU/ml; T2D with e-cigarettes, 15.45 ± 1.14 μIU/ml) as shown in Table 4 and Figure 3.