Elsevier

Mayo Clinic Proceedings

Volume 81, Issue 12, December 2006, Pages 1615-1620
Mayo Clinic Proceedings

CONCISE REVIEW FOR CLINICIANS
The Metabolic Syndrome: Concepts and Controversy

https://doi.org/10.4065/81.12.1615Get rights and content

The metabolic syndrome is an insulin-resistant state characterized by a cluster of cardiovascular risk factors, including various combinations of abdominal obesity, glucose intolerance, hypertension, and atherogenic dyslipidemia (elevated triglyceride values, low high-density lipoprotein cholesterol levels, and small dense low-density lipoprotein cholesterol particles). The current epidemic of obesity and physical inactivity has led to an increased prevalence of this disorder. In this review, we discuss the history and pathogenesis of the metabolic syndrome, the controversy regarding the appropriateness of considering it a distinct diagnosis, and the importance of lifestyle modification in its prevention and treatment. The need for all cardiovascular risk factors to be treated, whether or not they are components of the metabolic syndrome, is emphasized. Recent discussions in the literature regarding the continued use of the term metabolic syndrome should be considered a healthy academic debate that hopefully will stimulate ideas and innovative research to improve patient care.

Section snippets

DEFINITIONS

The World Health Organization (WHO) first defined the syndrome in 19983 and called it the metabolic syndrome, a term that had been used by Zimmet4 in 1991 to describe this cluster of findings. The WHO criteria for the metabolic syndrome required the presence of diabetes mellitus (DM), impaired fasting glucose, impaired glucose tolerance, or insulin resistance (assessed by the euglycemic insulin clamp technique) plus 2 additional factors. In 1999, the European Group for the Study of Insulin

CLINICAL IMPORTANCE

The pandemic of obesity, metabolic syndrome, and diabetes has sparked a tremendous interest in the medical literature. A MEDLINE search limited to English-language articles with the terms metabolic syndrome, insulin resistance syndrome, or syndrome X in the title returned 4024 articles published during the past 5 years, 1408 of which were published in the 12 months ending in March 2006.

Using measured heights and weights, results from the National Health and Nutrition Examination Survey indicate

PATHOGENESIS

The prevailing theory is that in most people with the metabolic syndrome, the development of obesity and physical inactivity leads to insulin resistance and compensatory hyperinsulinemia. Most insulin-resistant individuals are able to maintain the degree of hyperinsulinemia required to prevent decompensation of glucose homeostasis. If pancreatic insulin secretion fails to increase adequately, impaired glucose tolerance or DM develops. Genetic factors probably play a role in the varied clinical

RECENT CONTROVERSY

The ADA and the European Association for the Study of Diabetes (EASD) recently published a joint statement questioning the clinical value of the metabolic syndrome.20 Their concerns were as follows: (1) the criteria for the diagnosis of metabolic syndrome are ambiguous, and the rationale for thresholds is ill defined; (2) the value of including DM in the definition of metabolic syndrome is questionable; (3) the validity of using insulin resistance as the unifying etiology is uncertain; (4)

DISCUSSION

The NCEP ATP III criteria have definite flaws. First, the 5 criteria and the cutoffs appear to be arbitrary and not evidence based. Second, the risk factor values are continuous and must be considered as such, not just as present or absent. The fact that CVD risk increases with increasing blood glucose levels, systolic blood pressure, and LDL cholesterol values has been well documented. Third, important risk factors such as LDL cholesterol, cigarette smoking, family history, and age are not

CONCLUSION

Whether the constellation of vascular risk factors is called metabolic syndrome, insulin resistance syndrome, syndrome X, increased cardiometabolic risk, or another name is of limited clinical importance. The fact is that physicians are seeing increasing numbers of persons, including children, with obesity and varying combinations of glucose intolerance or DM, hypertension, and dyslipidemia. Simple solutions for the public health issue of obesity and lack of exercise are not available and will

Questions About Metabolic Syndrome

  • 1.

    Which one of the following is the correct current estimated prevalence of obesity (BMI, ≥30 kg/m2) in US adults aged 20 to 74 years?

    • a.

      10%

    • b.

      20%

    • c.

      31%

    • d.

      65%

    • e.

      90%

  • 2.

    Which one of the following is not a NCEP ATP III criterion for diagnosis of the metabolic syndrome?

    • a.

      Increased WC

    • b.

      Blood pressure ≥130/85 mm Hg

    • c.

      Elevated uric acid

    • d.

      Triglycerides ≥150 mg/dL

    • e.

      Fasting plasma glucose ≥100 mg/dL

  • 3.

    The lipid pattern observed in individuals with the metabolic syndrome is characterized by which one of the

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