Five studies also reported on clinical factors (patients affected by OSA [17], non-diabetic patients [18], higher morning arterial pressure [17]) and laboratory factors (higher CRP value [16,18], higher MMP-9 level [18] and eGFR < 90 mL/min/1.73 m [2,20]), yet, once again, further studies are needed to confirm these results. Here, MMP9 is linked to obstructive sleep apnea syndrome.