Metabolic Syndrome and the Role of Insulin Resistance
By Axel F. Sigurdsson MD January 29, 2015
SOURCE:Doc's Opinion docsopinion.com/
(About Heart Disease, Nutrition, Healthy Lifestyle and Prevention of Disease)
The first description of metabolic syndrome can be traced to Eskil Kylin (1889-1975), a Swedish physician who described a cluster of conditions, including high blood sugar, high blood pressure, obesity, and high blood levels of uric acid which can lead to gout
The metabolic syndrome is a constellation of risk factors, most usually associated with increased body weight, fat accumulation around the abdominal organs often termed central, or visceral obesity, and increased resistance to the effects of insulin.Other names that have been used to describe the metabolic syndrome are syndrome X, the insulin resistance syndrome, the deadly quartet and obesity dyslipidemia syndrome. The prevalence of metabolic syndrome has grown rapidly..
Data from NHANES III have shown that factors associated with the risk of developing metabolic syndrome, apart from age, race and body weight, are postmenopausal status among women, smoking, low household income, no physical inactivity.
The fact that the metabolic syndrome is highly related to the risk of developing type 2 diabetes and cardiovascular disease underscores the importance of understanding, preventing and treating the disorder.It is debated whether the factors associated with the metabolic syndrome have enough in common to warrant classifying it as a true syndrome.
Although the metabolic syndrome is often referred to as a uniform entity, it is important to recognise that no single underlying mechanism has been defined, nor may one exist. Thus, the syndrome could range from a cluster of unrelated risk factors to a constellation of factors linked through a common underlying mechanism. For the individual, it may be more practical to look at the different components of the metabolic syndrome because the clinical picture varies between patients.
Gaining weight is a major risk factor for the metabolic syndrome. Data from NHANES III have shown that the metabolic syndrome was present in 5 percent of normal weight individuals, 22 percent of those who were overweight and 60 percent of those who were obese.
The five conditions described below are used to define the metabolic syndrome. Three of these must be present in order to be diagnosed with the condition.
•Abdominal obesity, defined as waist circumference > 40 inches (102 cm) in men and > 35 inches (88 cm) in women
•A high triglyceride level in blood, defined as > 150 mg/dL (1.7 mmol/L)
•A low HDL cholesterol level in blood, defined as < 40 mg/dL (1 mmol/L)
•High blood pressure, defined as > 130/85 mmHg or drug treatment for elevated blood pressure
•Elevated blood sugar, defined as fasting blood glucose >100 mg/dL (5.6 mol/L) or drug treatment for diabetes
Abdominal obesity appears to play a key role. A large waistline alone identifies up to 46 percent of individuals who will develop metabolic syndrome within five years.
The rapidly increasing prevalence of obesity in most countries around the world is likely to raise the prevalence of the metabolic syndrome further in the near future.
Insulin resistance plays a key role in the pathophysiology of the metabolic syndrome and the term “insulin resistance syndrome” has been used by some experts .
Individuals with insulin resistance are at greatly increased risk to develop heart disease, type 2 diabetes, high blood pressure, stroke, nonalcoholic fatty liver disease, polycystic ovary syndrome, and certain forms of cancer.. However, there is currently no validated test for measuring insulin resistance in a clinical setting
The most widely used test is the homeostasis model assessment of insulin resistance (HOMA-IR), which employs fasting glucose and insulin levels. Due to biological variability requiring repeat testing and lack of insulin assay standardisation, HOMA-IR continues to be used more for research than for clinical applications.
Recently, a so-called Lipoprotein Insulin Resistance Index (LP-IR), based on blood measurements of lipoprotein subclasses and particle concentration, has been used to measure insulin resistance . This test is being performed in some laboratories in the US.
There are two major treatment targets in patients with the metabolic syndrome. The first aims at treating underlying causes such as obesity and physical inactivity. The second aims at treating cardiovascular risk factors if they persist despite lifestyle modification.
Lifestyle modification should focus primarily on weight reduction and increased physical activity.