Friday, June 2, 2023
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What is the significance of postprandial triglyceride levels compared with fasting triglyceride levels?
Response from Vera Bittner, MD, MSPH
Professor of Medicine, Section Head, Preventive Cardiology, University of Alabama at Birmingham, Birmingham, Alabama
In 1979, Zilversmit[1] proposed that atherogenesis was a postprandial phenomenon. Ingestion of a fatty meal results in the production of triglyceride-rich lipoproteins (chylomicrons and, secondarily, very-low-density lipoproteins), particles which are then metabolized to atherogenic remnants. Humans spend most of their time in a postprandial state, not in a fasting state, and their arteries are thus exposed to postprandial plasma most of the time. One would thus surmise that postprandial lipid values would correlate better with prognosis than fasting values.
This has indeed been shown in recent epidemiologic studies. Bansal and colleagues[2] analyzed the prognostic value of fasting and nonfasting triglyceride levels in a cohort of 26,509 healthy women enrolled in the Women's Health Study. After 11.4 years of follow-up, nonfasting, but not fasting, triglycerides in the upper tertile of the distribution were associated with an almost 2-fold increase in cardiovascular disease even after adjustment for age, blood pressure, smoking, use of hormone therapy, total and high-density lipoprotein cholesterol, diabetes mellitus, body mass index, and high-sensitivity C-reactive protein.[2] In another study published in the same issue of the Journal of the American Medical Association, authors from Denmark similarly concluded that nonfasting triglyceride levels were predictive of myocardial infarction, ischemic heart disease, and death in men and women.[3]
What are the practical implications of this observation? "Lipid tolerance testing" (analogous to glucose tolerance testing) has been suggested by some, but this is not practical for most practitioners and to date we have no data to suggest that treatment strategies should be altered based on such testing. It is important, however, not to dismiss triglyceride elevations in individuals who forget to fast for their regular blood draw. Such an elevation should prompt discussion with the patient about the link between such triglyceride elevations and insulin resistance, future cardiovascular disease, and the importance of lifestyle modifications (quality and quantity of food, weight management, physical activity).[4-9]
Current treatment guideline recommendations are based on fasting lipoprotein measurements.[4] Low-density lipoprotein cholesterol remains the primary target of therapy for patients with borderline fasting hypertriglyceridemia (150-199 mg/dL). For fasting triglyceride levels between 200 and 499 mg/dL, non-high-density lipoprotein cholesterol becomes a secondary target of therapy. If fasting triglyceride levels are very high (≥ 500 mg/dL), prevention of acute pancreatitis is the primary goal, and triglyceride-lowering drugs (fibrates, nicotinic acid, fish oil) become first-line therapy in these patients.
This activity is supported by an independent educational grant from GlaxoSmithKline.
