INS and diabetes mellitus: The strong positive correlation of resting HR with fasting insulin levels in the present study is in line with other studies demonstrating that insulin itself (even in different entities such as: fasting insulin, intact proinsulin, split proinsulin, or acute insulin response [31]) can influence the cardiac autonomic nervous system by reducing parasympathetic function and potentiating sympathetic drive in patients with [32] and without diabetes [33].