Metabolic syndrome (MetS), also referred to as syndrome X or insulin resistance syndrome, affects one in three adults over the age of 20 and approximately 44 percent of individuals ages 60-69.
MetS consists of a cluster of metabolic abnormalities that place individuals at risk for type 2 diabetes mellitus and shares many of the same risk factors of cardiovascular disease (CVD). Clinical abnormalities include dyslipidemia (elevated triglycerides and low high-density lipoprotein cholesterol), elevated fasting glucose, abdominal adiposity and hypertension.
MetS is reaching epidemic rates in the U.S. Therefore, it is vital to develop and implement preventive health programs that positively impact patient outcomes. Therapeutic lifestyle interventions are the first-line therapy for this syndrome and consist of weight loss and physical activity.
Patient self-management is essential to treatment success of MetS. There is evidence self-management skills can be learned and sustained by increasing knowledge, role modeling, and enhancing self-efficacy in individual and group educational settings.
To assist the nurse with patient counseling, this article will describe MetS signs and symptoms, prevalence, evidence-based lifestyle therapies and components of successful self-management counseling.
Prevalent And Increasing Problem
MetS is a constellation of symptoms that include insulin resistance, abdominal obesity, elevated blood pressure and lipid abnormalities, such as elevated levels of triglycerides and low levels of high-density lipoprotein cholesterol (HDL-C).1 It has a designated ICD9 code (277.7), yet lacks a consistent definition by the various organizations.
The National Cholesterol Education Program-Adult Treatment Panel's (NCEP-ATP III) diagnostic criteria for metabolic syndrome are any three co-occurrences of abnormal findings of the following: waist circumference, triglycerides, HDL-C, blood pressure and fasting glucose (see Figure).2,3
NCEP guidelines do not require a measure of insulin sensitivity to diagnose MetS. The American Association of Clinical Endocrinologists includes hyperinsulinemia associated with obesity, as well as acanthosis nigricans (hyperpigmentation of the skin), overweight/obesity with a body mass index 25 and hyperuricemia as major criteria of MetS (see Figure).4
The prevalence of MetS varies by age, sex, race and ethnicity, with rates ranging from 16-37 percent in the U.S. Researchers report that, of the 8,814 persons in the Third National Health and Nutrition Examination Survey, age-adjusted prevalence of MetS was 23.7 percent.
Of those participants ages 60-69, 43.5 percent met diagnostic criteria. Extrapolating from the 2000 census data, the expected prevalence reaches nearly 47 million U.S. residents with a triad of insulin-resistant syndromes.5
In this same survey, white individuals and Mexican-Americans had the highest prevalence of abdominal obesity, hypertriglyceridemia and low high-density lipoproteins; African-American men were more likely to present with hypertension. These findings demonstrate MetS is a highly prevalent and increasing condition in the U.S.
The condition's cluster of risk factors may be responsible for much of the excess CVD morbidity among overweight and obese patients. Twenty million U.S. adults between the ages of 40 and 74 years have impaired glucose tolerance and are at risk for diabetes, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
Additionally, MetS is a strong independent predictor of type 2 diabetes mellitus.6 The prevalence of MetS increases with age and adult weight gain. In a study of 1,209 Finnish men with MetS who were not originally diagnosed with diabetes, cancer or CVD, CVD mortality risk was increased 2.9 fold and all-cause mortality was increased 4.9 fold.7
Mortality also was evaluated in the Veterans Affairs High-Density Lipoprotein Intervention Trial (VA-HIT) in men with known coronary disease.8 Patients without diabetes but with insulin resistance had higher relative risk of CVD events than individuals without insulin resistance. These findings related to increased morbidity and mortality associated with MetS emphasize the advantages of early identification and treatment of this disease.
Therapeutic lifestyle changes are the primary therapy for MetS and its component features. The initial treatment for each of the syndrome's components includes the following:
- obesity is lifestyle modification;
- dyslipidemia is weight loss, exercise and low-fat diet;
- hypertension is sodium restriction, weight reduction and exercise; and
- glucose intolerance is weight loss and increased exercise levels.2,9
Aggressive management of MetS components should decrease the morbidity of progressive CVD, hypertension and diabetes mellitus. Modest weight loss and increased levels of physical activity have been shown to be effective in preventing or delaying the onset of diabetes in individuals with impaired glucose tolerance.7
Meta-analysis of nonrandomized trial data and data from randomized trials have validated the health benefits of low-carbohydrate diets and reduced-fat diets among people with diabetes and MetS patients. Patients randomized to either low-carbohydrate or low-fat diets had similar weight loss (P < 0.001) by the end of the studies, but the low-carbohydrate diet groups were independent predictors of improvement in elevated triglycerides and insulin sensitivity (P=0.01).10
Similar findings were observed in a 1-year multicenter controlled trial of 63 obese men and women who were randomly assigned to various diets. Dieters lost similar amounts of weight, improved HDL-C and triglycerides, and significantly decreased diastolic blood pressure and insulin sensitivity.11
Two trials have compared a low-fat diet program that included lifestyle management strategies of smoking cessation, stress management training and moderate exercise with the American Heart Association Step 1 diet.12,13 The final results showed improved risk factor profiles, weight loss and improvements in coronary angiographic appearance at 1 year.
In the Diabetes Prevention Program, it was reported that higher levels of moderate and vigorous physical activity were inversely related to MetS among ethnically diverse women.14 A 7 percent reduction in body weight and 150 minutes of physical activity per week over 3 years reduced the incidence of type 2 diabetes mellitus by 58 percent compared with the outcomes seen in control group subjects receiving usual care.
The Insulin Resistance Atherosclerosis Study compared different levels of physical activity and their effects on insulin sensitivity in 1,467 men and women. Findings supported both nonvigorous and vigorous levels of activity to increase insulin sensitivity and led to their recommendations of moderate physical activity for 30 minutes per day on most days of the week.15
Researchers studied the outcomes of a medically supervised rapid weight loss program and correlations of weight change with the components of MetS. The authors found a loss of 6.5 percent in weight resulted in significant reductions of systolic (11.1 mm Hg) and diastolic (5.8 mm Hg) blood pressure, glucose (17 mg/dL), triglycerides (94 mg/dL) and total cholesterol (37 mg/dL) at 4 weeks postintervention (P=<.001).16 At the end of the study, due to their weight loss, most participants no longer met MetS diagnosing criteria.
It is important to note MetS patients who improve health outcomes through lifestyle change are dependent on their sustained self-management skills to maintain these health improvements.