Introduction

We make no apology for raising the issue of syndrome X again - for the third time in 18 months! Syndrome X is also known as the metabolic syndrome and the insulin resistance syndrome. It was described to help explain the fact that some men with high blood pressure, although being treated with appropriate drugs (antihypertensives), were still having heart attacks at an unexpectedly high rate. They were usually moderately fat around the middle, had raised blood sugar levels, and showed resistance to the normal effects of insulin (i.e. insulin didn't lower the blood sugar as readily as in normal persons). Their blood lipid levels showed that the "good" cholesterol -- the high-density lipoprotein cholesterol (HDL-C) - was low, while their triglyceride level was increased. (All this was discussed in a previous article "Syndrome X - Complicated, But Important" -- see link below).

A recent report of a survey made in the USA in 1988 - 1994¹ has shown that the metabolic syndrome (this is now becoming the more common name) is much more widespread than we thought. This report, recently published in the Journal of the American Medical Association, is summarized here.

Method

For the purpose of this survey, the new definition for the metabolic syndrome (syndrome X) was used.² The subject has to have three or more of the following:

• Waist circumference greater than 40 inches (102 cm) in men, greater than 35 inches (88 cm) in women
• A serum triglyceride level above 150 mg/dL (1.7 mmol/L)
• 'Good' cholesterol (HDL) below 40 mg/dL (1.04 mmol/L) in men, below 50 mg/dL (1.29 mmol/L) in women
• Blood pressure raised; above 135/85 mm Hg
• Fasting blood glucose above 110 mg/dL (6.1 mmol/L)

If people were currently taking antihypertensives or antidiabetic drugs, they were counted as if they had a high blood pressure or a raised fasting blood glucose.

The percentage of people with the metabolic syndrome was calculated for this USA population sample according to their age, gender, and race or ethnicity. The results were adjusted to make them representative for the whole USA population, by using the age composition of the survey sample and that of the country's population.

Results

There were over 8,800 people in the survey, about equally men and women. There were about 3,600 white people, 2,400 African-Americans, and 2,450 Mexican-Americans.³

Overall, 22% of the sample had the metabolic syndrome, which would represent 24% of the US population after the age-adjustment. The syndrome increased quite dramatically with age, from 6.7% in 20 to 29 year-olds, with about 20% in 30 to 39 year-olds, to 43% in 60 to 69 year-olds. In remained at about 40% in the over-70s. There was hardly any difference between men and women in the overall numbers.

Mexican-Americans had the greatest percentage of people with the metabolic syndrome -- 36% in men and 28% in women, overall. African-American women were more likely to have the syndrome than men -- 26% over 16%. White men and women both had about 23% of people with the syndrome, when the age groups were combined.

Conclusions

The data used for this survey were collected almost 10 years ago. That isn't any reason for optimism, though, as the obesity and diabetes problem in the USA has increased in the last ten years, so it's likely that the metabolic syndrome is more common, too.

Some people may say that the syndrome is not a description of a single thing or entity, but rather a convenient grouping of people with three or more cardiovascular risk factors. The question is academic -- there is no doubt that people with syndrome X are at increased risk of illness (chiefly diabetes and cardiovascular disease) and death.

The authors of the present study are rather gloomy about the chances of tackling the problem. Growing numbers of US-style fast-food restaurants in many other countries in the world means that the metabolic syndrome will probably emerge everywhere that actual food shortages don't exist. Let us hope that the US experience serves as a warning to others. Too much of the wrong sort of food, coupled with a lack of physical activity, can certainly produce the typical signs of the metabolic syndrome.

If you are a regular reader of these pages, I am 'preaching to the converted'. You certainly know by now all about the needs for a healthy lifestyle. But the alarmingly high percentage of young people with syndrome X makes it important that all of us urge our children, and their children, to adapt a healthier lifestyle early enough, before it becomes too hard to make the necessary changes.