IGF1 and metabolic syndrome: Linear interaction effects, shown in Fig. 2A, B revealed that in subjects with MetS and low HDL-C (e.g., 42 mg/dL), as glycemia increased, a reduction in average IGF-1 levels was observed; however, for higher values of HDL-C (e.g., HDL-C = 56 mg/dL), IGF-1 was positively related to glycemia (Fig. 2A).