syndrome X (obesity/insulin resistance/hypertension/lipids)
Last reviewed 10/2022
The National Cholesterol Education Program (NCEP) Adult Treatment Panel (ATP) III guidelines suggested that a diagnosis of metabolic syndrome (previously known as syndrome X) where three or more of the following risk factors are present:
- central obesity
- elevated triglyceride
- low HDL
- raised blood pressure
- raised fasting plasma glucose
More recently the International Diabetes Federation (IDF) (3) have defined criteria for metabolic syndrome where metabolic syndrome is diagnosed if the patient has a 'large waist' plus any other two risk factors.
| Risk Factor | Defining Level NCEP ATP III Any three of these: | Defining criteria IDF Large waist plus any two: |
|
Central (abdominal) obesity* waist circumference |
men > 102 cm (>40 in) women > 88 cm (>35 in) |
men > 94 cm (> 37 inches) women > 80 cm (> 32 inches) |
| high-density lipoprotein cholesterol |
men <1.0 mmol/L (<40mg/dL) women <1.3 mmol/L (<50mg/dL) | men < 1.0 mmol/L (40 mg/dL) women <1.3 mmol/L (50 mg/dL) |
| triglycerides | >= 1.7 mmol/L (>= 150mg/dL) | >= 1.7 mmol/L (>=150 mg/dL) |
| blood pressure | >= 130/85 mmHg | >= 130/85 mmHg |
| fasting plasma glucose | >= 6.6 mmol/L (>=110mg/dL) | >= 5.6 mmol/l (>=100 mg/dL) |
Interestingly the IDF criteria suggests a smaller waist circumference (for men and women) and also a lower fasting glucose level.
* central obesity is more highly correlated with the metabolic risk factors than body mass index (BMI) and therefore measurement of waist circumference (around the navel) is recommended to identify the bodyweight component of metabolic syndrome
The metabolic syndrome:
- is a collection of both non-lipid and lipid risk factors of metabolic origin
- insulin resistance is the basic underlying
mechanism
- obesity probably leads to insulin resistance by the associated increased rate of non-esterified fatty acids causing post-receptor defects in insulin's action. Other mechanisms include mutation of gene encoding insulin receptor; circulating autoantibodies to the extracellular domain of the insulin receptor
- insulin
resistance is associated with:
- obesity
- being of Asian origin
- pregnancy
- acromegaly
- polycystic ovaries
- cystic fibrosis
- ataxia telangiectasia
- acute and chronic renal failure
- Prader-Willi syndrome
- Werner's syndrome
- drugs including rifampicin, isoniazid
- increases CHD risk at any given LDL level
- first-line therapies (1) are:
- weight reduction
- increased physical activity - regular physical activity reduces very low-density lipoprotein (VLDL) levels, blood pressure and insulin resistance and can have beneficial effects on cardiovascular function
- LDL reduction
- also treatments for hypertension, plus aspirin and treatments to reduce triglycerides and elevate HDL, have also been shown to reduce coronary heart disease risk (1)
- other lifestyle factors (in addition to physical activity) must be addressed e.g. moderation in alcohol intake, and cessation of smoking and monosaturated fat in the diet
Notes:
- the
IDF define waist circumference based on different population groups (3)
- increased
waist circumference for South Asians
- Male >= 90 cm
- Female >= 80 cm
- increased waist circumference for Chinese
- Male >= 90 cm
- Female >= 80 cm
- increased
waist circumference for South Asians
Reference:
- Executive Summary of the third report of the National Cholesterol Education Program (NCEP) expert panel on detection, evaluation and treatment of high blood cholesterol in adults (Adult Treatment Panel III) JAMA 2001; 285:2486-97.
- Reaven GM. Role of insulin resistance in human disease. Diabetes 1983; 37:1595-1607.
- www.idf.org