06/25/2024

Ann Dunaway

The metabolic syndrome - also known as syndrome X, insulin resistance syndrome and the deadly quartet - can no longer be considered as an issue affecting only adults, as it is rapidly spreading among the children’s population. Because there are several definitions of the metabolic syndrome it is difficult to calculate its  exact extension. Recently, the American Heart Association (AHA) and the National Heart, Lung, and Blood Institute(NHLBI) reached a mutual agreement that closely resembles the definition given by the National Institute of Diabetes, paving the way for a better understanding and identification of the metabolic syndrome in clinical and research areas.

According to the definition presented in the scientific announcement in 2005 of the AHA / NHLBI, the metabolic syndrome is a group of various related factors that encourage atherosclerotic cardiovascular disease (CVD). It is closely associated with increased risk insulin-dependent diabetes (diabetes mellitus) type 2.

Risk Factors and Diagnostic Criteria

Obesity and insulin resistance are the two most significant risk factors that support the development of the metabolic syndrome. In the context of the metabolic syndrome, obesity is determined in relation to general type obesity and increased waist perimeter >102 cm for men and >89 cm for women. For Asian Americans, the limit is reduced to > 89 cm for men and >78cm for women. Insulin resistance is clinically difficult to measure but is closely related to abdominal obesity.

In 2001, the National Cholesterol Education Program (NCEP) Adult Education Phase III, has developed a set of criteria for clinical diagnosis of the metabolic syndrome in adults. In the announcement of the AHA / NHLBI it was supported that these criteria are sufficient to identify the metabolic syndrome, with some minor adjustments. A person is considered to be suffering from metabolic syndrome when three of the five criteria exist. The five criteria (see table) include:

• Increased waist circumference
• Increased level of triglycerides
• Reduced levels of "good" cholesterol and lipoproteins
• Increased blood pressure
• Increased level of fasting blood glucose

The main changes made by the AHA / NHLBI was to include in the criteria the people receiving medication for any of the five conditions listed in the criteria, and the assumption that these people have an indicator based on the concentration of fasting blood insulin and glucose levels which approaches a sensitivity to insulin. The HOMA-IR (Homeostatic indexes of insulin resistance) ie homeostatic indices of insulin resistance are directly related to studies for euglycemic and hyperinsulinemic blockade which is not suitable for clinical application. Exclusion studies are the golden rules for determining insulin resistance in vivo. Insulin is injected in the bloodstream to suppress hepatic glucose production and to determine the response of the body at higher levels of circulating glucose. Although more research is needed, the value of HOMA-IR at or near 3 has been shown that almost reaches the insulin resistance and the increased risk for metabolic syndrome in children and adults.

Hirschler et al found that insulin resistance at a young age was closely associated with waist perimeter and systolic blood pressure. In this study both the HOMA-IR and proinsulin levels were used to assess insulin resistance. The proinsulin is the substance from which the pancreas produces insulin. Elevated levels of fasting intact proinsulin is indicative of insulin resistance. Low aspiration of blood glucose by the cells resulted in higher concentrations associated with increased insulin secretion from the cells and demonstrated that this increased insulin resistance was the major cause of increased levels of proinsulin.

Hypertension, dyslipidemia, high blood sugar

Other three diagnostic criteria for the metabolic syndrome in adults - hypertension, dyslipidemia and high fasting blood glucose level - are indicative of insensitivity to insulin and possibly metabolic syndrome in the pediatric population as well. Researchers have taken the criteria of the National Cholesterol Education Programme (NCEP) Adult Education Phase III for adults and proposed critical points for children and adults. While certain values ​​are proposed for hypertension, dyslipidemia and high fasting glucose, waist circumference and blood pressure are dependant on age and gender. So the values ​​for these two measures depend on the percentile for gender and age. For the state of the proposed criteria for children and adults see the table below.

Conclusion

The metabolic syndrome is a complex grouping of conditions that increase the risk for cardiovascular disease and type 2 diabetes. The metabolic syndrome is closely associated with obesity and insulin resistance. Obesity is associated with multiple health risks, many of which are only now being clarified. As levels of obesity are rising, the problems that accompany them are also increasing. Unfortunately, obesity and related health problems such as cardiovascular disease (CVD) and diabetes type 2 are not confined within the affected population. All ages and nationalities "battle against obesity" and the criteria used for one group may not be suitable for a different group.

For this reason, there must be a continuous research and consensus of the subject of metabolic syndrome, especially for children and adults. The model presented by the National Cholesterol Education Program (NCEP) Adult Education Phase III and modified by the AHA / NHLBI is a good starting point.

The better we identify young people with or who have a risk for developing the metabolic syndrome, the more competent and effective we can be in order to offer the appropriate treatment.

By Ann Dunaway, BA, BS and Barbara L. Hopkins, MMSc, RD
Cardiovascular Nutritionist Spring 2006.