Summary
Triglycerides are the main form of fat stored in adipose tissue and the predominant component of VLDL particles circulating in the blood. Elevated fasting triglycerides are a hallmark of metabolic syndrome, insulin resistance, and poor diet — and are an independent risk factor for cardiovascular disease and pancreatitis. A fasting sample is essential for accurate measurement.
Triglycerides consist of a glycerol backbone with three fatty acid chains. They provide the body’s primary energy storage — adipose tissue is almost entirely composed of stored triglycerides. In the bloodstream, triglycerides are carried in VLDL (produced by the liver) and chylomicrons (produced in the gut after a meal).
Elevated fasting triglycerides reflect either excess VLDL production (driven by insulin resistance, excess alcohol, high carbohydrate intake, or obesity) or impaired clearance. Very high triglycerides (> 10 mmol/L) carry a significant risk of acute pancreatitis — a potentially life-threatening complication.
Triglycerides and HDL are inversely related: as triglycerides rise, HDL typically falls. The combination of high triglycerides and low HDL (the ‘atherogenic dyslipidaemia’ of metabolic syndrome) is associated with particularly high cardiovascular risk, especially in type 2 diabetes.
What It Is
Triglycerides (triacylglycerols) are ester compounds formed from glycerol and three fatty acids. Dietary triglycerides are absorbed by the gut, packaged into chylomicrons, and transported to adipose tissue and muscle for storage or oxidation. The liver synthesises additional VLDL triglycerides — particularly when insulin is elevated, causing increased de novo lipogenesis.
After a meal, triglycerides rise transiently for 4–8 hours as chylomicrons clear (postprandial lipaemia). This is why fasting (10–12 hours) is essential for a valid measurement — eating even small amounts of food can double triglyceride levels.
Reference ranges in UK adults: optimal 5.6 mmol/L; extremely high (pancreatitis risk) > 10 mmol/L.
Functions
Energy storage
Triglycerides are the body's primary long-term energy store — adipose tissue releases fatty acids for fuel during fasting and exercise.
Metabolic syndrome indicator
Fasting triglycerides > 1.7 mmol/L are one of five criteria for metabolic syndrome and reflect underlying insulin resistance.
Cardiovascular risk factor
Elevated triglycerides independently increase cardiovascular risk — particularly in combination with low HDL and elevated LDL.
Pancreatitis risk marker
Very high triglycerides (> 10 mmol/L) carry a significant risk of acute pancreatitis — a medical emergency requiring urgent intervention.
Reference Ranges
Fasting Triglycerides
Measured in mmol/L| Status | Range (mmol/L) | Range (mg/dL) | What it means |
|---|---|---|---|
| Optimal | < 1.7 | < 150 | Normal fasting triglycerides — low metabolic risk. |
| Borderline | 1.7–2.2 | 150–199 | Borderline high — review diet, alcohol intake, and metabolic risk factors. |
| Elevated | 2.3–5.6 | 200–499 | Elevated — metabolic syndrome likely. Cardiovascular risk increased. Active management required. |
| Very high | > 5.6 | > 500 | Very high — pancreatitis risk significant. Specialist referral required. |
Valid only from a fasting (10–12 hour) sample. Non-fasting triglycerides > 2.0 mmol/L are also clinically significant for cardiovascular risk. Friedewald LDL equation is inaccurate when triglycerides > 4.5 mmol/L.
Symptoms of Imbalance
Mildly to moderately elevated triglycerides are usually asymptomatic. Very high levels may cause eruptive xanthomata and carry pancreatitis risk.
- Very low triglycerides are generally not clinically significant
- May be seen with very low fat diets or malabsorption
- Usually asymptomatic until very high levels
- Eruptive xanthomata (small yellow-white skin papules) in very high triglycerides
- Lipaemia retinalis (creamy blood vessels in retina) at extreme levels
- Acute pancreatitis: severe upper abdominal pain radiating to back, nausea, vomiting
Causes of Imbalance
- Very low fat diet
- Malabsorption
- Hyperthyroidism
- Metabolic syndrome and insulin resistance (most common)
- Type 2 diabetes
- High intake of refined carbohydrates, sugar, and fructose
- Excess alcohol consumption
- Obesity, particularly central adiposity
- Familial hypertriglyceridaemia (genetic)
- Medications: thiazides, beta-blockers, corticosteroids, oestrogens, retinoids
- Hypothyroidism, kidney disease
FAQs
Triglycerides rise dramatically after eating — even a light meal can double fasting levels as the gut absorbs dietary fat into chylomicrons. For an accurate fasting triglyceride level (which reflects hepatic VLDL production and basal metabolic status), a 10–12 hour fast is required. Water is fine. If you ate within 12 hours, the result will be uninterpretable.
The most impactful interventions are: (1) reduce refined carbohydrates and sugar — fructose particularly drives hepatic triglyceride synthesis; (2) reduce or eliminate alcohol — even moderate consumption significantly raises triglycerides; (3) lose excess weight — 5–10% weight loss can halve triglycerides in insulin-resistant individuals; (4) increase omega-3 fatty acids (oily fish 3×/week or concentrated EPA/DHA supplements). These changes can reduce triglycerides by 30–50%.
Yes — this is the most serious acute complication of very high triglycerides. The mechanism involves hydrolysis of VLDL by pancreatic lipase releasing large amounts of toxic free fatty acids, causing direct acinar cell injury. The threshold for pancreatitis risk is generally > 10 mmol/L (> 900 mg/dL), though some patients develop pancreatitis at lower levels. Triglyceride-induced pancreatitis is a medical emergency requiring hospitalisation and rapid triglyceride lowering.
Yes, significantly. Alcohol is metabolised to acetaldehyde and then acetate in the liver, which stimulates hepatic de novo lipogenesis (fat synthesis) and VLDL secretion. Even modest alcohol consumption (2–4 units/day) raises fasting triglycerides — heavy drinking can cause severe hypertriglyceridaemia, sometimes exceeding 10 mmol/L. Alcohol cessation normalises triglycerides within 2–4 weeks.
Atherogenic dyslipidaemia is the lipid pattern typical of metabolic syndrome and type 2 diabetes: elevated triglycerides (> 1.7 mmol/L) + low HDL (< 1.0 mmol/L in men, < 1.2 mmol/L in women) + elevated small dense LDL. This pattern carries higher cardiovascular risk than elevated LDL alone, but is often missed because total LDL-C may be within the reference range. Non-HDL cholesterol and ApoB better capture this risk.
References
- Hegele RA, et al. Polygenic dyslipidemias and cardiovascular risk. J Clin Lipidol. 2018;12(5):1059–1065. View source
- Nordestgaard BG, et al. Fasting is not routinely required for determination of a lipid profile. Eur Heart J. 2016;37(25):1944–1953. View source
- Miller M, et al. Triglycerides and cardiovascular disease: a scientific statement from the American Heart Association. Circulation. 2011;123(20):2292–2333. View source