Which of the following is NOT a criterion for diagnosing metabolic syndrome?

The correct response is based on the established diagnostic criteria for metabolic syndrome, which typically includes various measurements related to increased cardiovascular risk and metabolic disorders. Waist circumference is a key indicator of abdominal obesity, triglycerides are assessed to evaluate lipid abnormalities, and blood pressure is crucial for identifying hypertension, all serving as risk factors in metabolic syndrome.

Serum creatinine levels, however, are not included in these diagnostic criteria. While serum creatinine can indicate kidney function or damage, it does not directly relate to the components of metabolic syndrome such as obesity, dyslipidemia, or hypertension. Therefore, among the listed options, serum creatinine levels do not fulfill the role of contributing to the diagnosis of metabolic syndrome, making it the correct choice here.