About This Page
This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- IDF criteria: central obesity (waist ≥94 cm men, ≥80 cm women — ethnic-specific) PLUS ≥2 of: raised TG ≥1.7, low HDL <1.03 (M)/<1.29 (F), raised BP ≥130/85, raised fasting glucose ≥5.6
- Insulin resistance is the central pathophysiological driver
- Doubles cardiovascular disease risk and increases T2DM risk 5-fold
- Management is aggressive lifestyle modification + treat each component individually
- Not a separate "disease" to treat per se — it is a risk assessment framework that identifies clustering of metabolic risk factors
- Strongly associated with NAFLD, PCOS, obstructive sleep apnoea, and hyperuricaemia/gout
Overview
Metabolic syndrome is a constellation of interrelated metabolic abnormalities that cluster together more often than expected by chance. The unifying pathophysiology is insulin resistance, driven primarily by excess visceral adiposity. The individual components — central obesity, dyslipidaemia (raised triglycerides, low HDL), hypertension, and impaired glucose homeostasis — each increase cardiovascular risk, but their combination confers risk greater than the sum of individual parts. Several diagnostic criteria exist (IDF 2005, ATP III, WHO); the IDF definition requires central obesity as an obligatory component. Metabolic syndrome is not a separate disease entity but a useful clinical framework for identifying patients at particularly high cardiovascular and diabetes risk who warrant aggressive intervention.
Epidemiology
Metabolic syndrome affects approximately 20–25% of UK adults, with prevalence increasing with age, obesity, and socioeconomic deprivation. It is more common in South Asian, Black, and Hispanic populations (at lower BMI thresholds). Prevalence has risen dramatically in parallel with the obesity epidemic. Approximately 80% of patients with T2DM have metabolic syndrome. It is strongly associated with PCOS (present in up to 40% of women with PCOS), NAFLD (present in ~90%), and obstructive sleep apnoea.
Clinical Features
Symptoms
Often asymptomatic — detected on routine screening
Symptoms of individual components: fatigue, polyuria/polydipsia (hyperglycaemia), headache (hypertension)
Symptoms of associated conditions: snoring (OSA), joint pain (gout), RUQ discomfort (NAFLD)
Signs
Central/abdominal obesity (increased waist circumference)
Hypertension (≥130/85 mmHg)
Acanthosis nigricans (marker of insulin resistance)
Skin tags (associated with insulin resistance)
Hepatomegaly (NAFLD)
Investigations
First-line
Waist circumferenceCentral to diagnosis. ≥94 cm (men) / ≥80 cm (women) for European populations. Ethnic-specific cut-offs: South Asian ≥90 cm (men) / ≥80 cm (women)
Fasting glucose or HbA1cFasting glucose ≥5.6 mmol/L or HbA1c ≥42 mmol/mol (or known T2DM)
Fasting lipid profileTriglycerides ≥1.7 mmol/L and/or HDL <1.03 (men) / <1.29 (women)
Blood pressure≥130/85 mmHg (or on treatment for hypertension)
Second-line
LFTsScreen for NAFLD (raised ALT)
UrateHyperuricaemia common (gout association)
QRISK3Cardiovascular risk assessment — metabolic syndrome components cluster to increase 10-year CVD risk
Specialist
Liver USS / FibroScanIf raised ALT — assess for NAFLD/NASH and fibrosis staging
1
Lifestyle modification (cornerstone)
- Weight loss: 5–10% reduces all metabolic parameters. Central target — reduce waist circumference
- Diet: Mediterranean-style, reduce refined carbohydrates and saturated fat, increase fibre
- Physical activity: ≥150 min/week moderate intensity — improves insulin sensitivity independently of weight loss
- Smoking cessation: amplifies cardiovascular risk in metabolic syndrome
- Alcohol moderation
2
Treat individual components to target
- Hypertension: ACEi/ARB first-line if T2DM or renal disease. Target <140/90 (or <130/80 if high-risk)
- Dyslipidaemia: atorvastatin if QRISK3 ≥10%. Fibrates for severe hypertriglyceridaemia (>10 mmol/L — pancreatitis risk)
- Hyperglycaemia: lifestyle first. Metformin + SGLT2i if T2DM (cardiorenal benefit)
- Assess overall cardiovascular risk (QRISK3) and manage holistically
Complications
- Cardiovascular disease: 2× increased risk of CVD events (MI, stroke) — the most important consequence
- Type 2 diabetes: 5× increased risk of developing T2DM
- NAFLD/NASH: Hepatic manifestation of insulin resistance — may progress to cirrhosis
- Chronic kidney disease: From hypertension + diabetes
- Gout: Hyperuricaemia from insulin resistance (reduced renal urate excretion)
UKMLA Exam Tips
- 1IDF criteria: central obesity (mandatory) + ≥2 of: raised TG, low HDL, raised BP, raised fasting glucose. Know the numbers
- 2Insulin resistance is the central driver — links all the components together
- 3Metabolic syndrome is not a separate diagnosis to "treat" — it is a clustering of risk factors that each require individual management
- 4Central obesity > BMI for metabolic risk. A patient with BMI 28 and waist 105 cm may have higher metabolic risk than BMI 32 with waist 90 cm
- 5Acanthosis nigricans = clinical marker of insulin resistance — look for it in exam photos
- 6South Asian populations: lower BMI and waist circumference thresholds for equivalent risk
practicetest your knowledge on metabolic syndromeApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — endocrine and beyond.
open q-bank