International criteria for a person having metabolic syndrome includes having three or more of the following measurements:

• Abdominal obesity. Waist circumference of greater than 100cm (40 inches) in men, and greater than 90cm (35 inches) in women

• Blood triglyceride level of 1,7mmol/l (150 mg/dL) or greater

• HDL cholesterol of less than 1,0mmol/ (l40 mg/dL) in men or less than 1,3mmol/l (50 mg/dL) in women

• Blood pressure of 130/85 mmHg or greater

• Fasting plasma glucose of 5,7 mmol/l (100 mg/dL) or greater

The criteria might slightly differ from this depending on the country. According to this criteria metabolic syndrome affects about one third of the people in western countries.

Having just one of these conditions doesn't mean one has metabolic syndrome. But it does mean having a greater risk of serious disease. And if one develops more of these conditions, your risk of complications, such as type 2 diabetes and heart disease rises even higher.

Sometimes metabolic syndrome is referred to as insulin resistance syndrome. Almost without exception insulin resistance is one of the underlying metabolic disturbances of metabolic syndrome. 

One might suffer from insulin resistance without showing any other signs of metabolic syndrome, but in many cases insulin resistance is manifesting itself as a systemic metabolic disturbance that is much more than only being resistant to insulin. Especially if one is being overweight it might be hard to make a difference between metabolic syndrome and insulin resistance. 

Very often a person with insulin resistance also suffers from increased blood pressure, abnormal cholesterol or triglyceride levels. In these cases, insulin resistance itself may actually be the one issue that has not been diagnosed yet. Therefore if one is suffering from other signs of metabolic syndrome there is a very high chance that they are insulin resistant as well, but not enough for the blood sugar levels to rise above normal. 

Causes and treatment of metabolic syndrome are very much in line with treatment and prevention of type 2 diabetes and insulin resistance. Lifestyle plays a big role in all of these metabolic conditions.