Metabolic syndrome

Also called Insulin resistance syndrome, Syndrome X

A cluster of risks that travel together and multiply each other. Not a disease so much as a warning with a decade of notice.

What it is

A cluster of findings that commonly occur together and, in combination, substantially raise the risk of type 2 diabetes, coronary heart disease and stroke.

The usual definition requires three or more of: a large waist; raised triglycerides; low HDL cholesterol; raised blood pressure; and raised fasting glucose.

Its value is as a way of seeing the whole picture. Each component on its own might be treated as borderline and watched; together they are not borderline at all, and the risk multiplies rather than adds. Somebody with three mildly abnormal numbers is in a different position from somebody with one.

The underlying mechanism is insulin resistance, and the driver is usually excess weight around the middle, physical inactivity and, importantly, genetics and social circumstance. It is substantially more common in people of South Asian heritage at lower body weights, which is why waist thresholds differ by ethnicity and why standard BMI cut-offs under-detect it.

It is also common in polycystic ovary syndrome, in severe mental illness and on antipsychotic medication, and in sleep apnoea and non-alcoholic fatty liver disease.

The point is that it is a warning with years of notice, and modest changes shift it.

Signs you might notice

Usually nothing that can be felt. It is defined by measurements.

A waist measurement above the threshold for the person's sex and ethnicity, which is the easiest single measure and is rarely taken.

Raised blood pressure.

Raised fasting glucose or HbA1c.

Raised triglycerides and low HDL cholesterol on a blood test.

Associated clues: skin tags and dark velvety patches in the neck folds and armpits, called acanthosis nigricans, which indicate insulin resistance; daytime sleepiness and snoring suggesting sleep apnoea; and fatty liver found incidentally on a scan.

Anybody with any one component should have the others measured. That is the whole practical point.

How it can affect day-to-day life

Being told about risk rather than illness is a hard message to act on, and lecturing reliably fails. What works is a specific, achievable change rather than an instruction to lose weight.

The social gradient is steep. Access to affordable food, safe places to be active, working hours and stress all shape this, and treating it as purely personal choice is both unfair and ineffective.

For people on antipsychotics, weight gain and metabolic change are drug effects that need monitoring and active management, not attributed to lifestyle. The annual physical health check exists for this. See annual health check.

Modest weight loss, around 5 to 10 per cent, produces disproportionate improvement in blood pressure, glucose and lipids.

The NHS Diabetes Prevention Programme is free, effective and available by referral or self-referral in England, and most eligible people have never heard of it.

Supporting someone well

Measure the waist. It is more informative than weight and almost never done.

Ask for the full set: blood pressure, HbA1c, and a lipid profile. One abnormal result should trigger the others.

Ask about the NHS Diabetes Prevention Programme; it works and it is free.

Aim for 5 to 10 per cent weight loss rather than an ideal weight; the benefit arrives early.

Build activity into what already happens rather than adding a gym; 150 minutes a week of anything that raises the heart rate.

Treat sleep apnoea if present; it worsens every component.

For anyone on antipsychotics, insist on the annual physical health check and act on the results.

Ask about statin treatment based on overall cardiovascular risk rather than cholesterol alone.

Stop smoking, which multiplies the same risks.

Where to get help

A GP practice or practice nurse for the measurements and for referral.

The NHS Diabetes Prevention Programme in England, which takes self-referral in many areas.

Diabetes UK helpline: 0345 123 2399.

British Heart Foundation on 0808 802 1234.