The diagnosis of metabolic syndrome calls for having the criteria of this syndrome, and this is fulfilled by conducting different tests and examining the patient . The patient’s medical history includes the assessment of OSA symptoms in all patients and PCOS in premenopausal women. Family record is helpful for determining CVD and DM risk. Measuring blood pressure and waist circumference provide the information required for diagnosing metabolic syndrome. Searches were conducted by two independent researchers in international (PubMed, Web of science, Scopus and Google scholar) and national (SID, Magiran) databases for related studies from the inception of the databases to September 2017 (without time limitation) in English and Persian languages. To ensure literature saturation, the reference lists of included studies or relevant reviews identifed through the search were scanned. When metabolic syndrome is diagnosed, fating lipid and glucose values need to be determined. The necessity of measuring other biological markers associated with insulin resistance is different for each individual. This measurements need to include ApoB, high-sensitivity CRP, fibrinogen, uric acid, microalbuminuria, and liver function tests. When there are symptoms of obstructive sleep apnea (OSA), a sleep study must test need to be taken from the patient. If PCOS is suspected, the values of testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) need to be measured according to clinical manifestations and anovaulation.