Evidence is mounting that elevated non-fasting triglyceride (TG) levels predict heart disease events, especially in women. According to two studies published July 18 in the Journal of American Medical Association, non-fasting TG levels are much better predictors of heart disease in both men and women than the more commonly used fasting TG test levels.
Triglycerides (TGs)—a type of fat in the blood—have historically played a controversial role in determining heart disease risk. They are routinely measured, along with cholesterol, when obtaining a lipid panel profile which is usually performed after a period of fasting. However, these two studies suggest that testing TG levels while being in the non-fasting state may be the key to better predicting future CV events.
The Women's Health Study followed 26,509 initially healthy American women for over 11 years. Of these, 20,118 had their TGs tested while in the fasting state and 6,391 women were tested without fasting. At the time of enrollment, TG levels correlated with traditional cardiac risk factors for both groups.
After an average of 11 years follow up, the women were tested again. After adjusting for age, blood pressure, smoking, and hormone-therapy use, both groups' TG levels were strongly associated with CV events. However, after making further adjustments for high cholesterol and diabetes markers in the fasting women, the association between TGs and CV events was substantially reduced.
This was not so in the non-fasting womens' group. When the same adjustments were made for high cholesterol and diabetes markers, the association between elevated TG levels and CV events was maintained and independent of the other markers. Researchers found that the elevated TG levels were most noticeable 2 to 4 hours after the participant's last meal, but that the levels gradually lessened with time. This is because TG fats are absorbed quickly into the bloodstream after eating, peak at around 4 hours, and then decline afterwards as they become more absorbed into the bloodstream.
Another study published in the same journal issue also confirmed that non-fasting elevated TG levels were associated with an increased risk of CV events. The researchers followed 7587 women and 6394 men from Denmark for an average of 26 years and found that CV events increased with non-fasting elevated TG levels.
Interestingly, in this study the association between elevated TG levels and CV events was more prevalent in women than in men. The researchers theorized that this was due to higher alcohol consumption in men, which has different effects on TG levels.
The results of these two studies emphasize that triglyceride levels are an important predictor of heart disease events, especially in women. While it is unclear if triglycerides will be used more often to measure heart disease risk or if the non-fasting test will become more common in light of these results, for now the recommendation that women should aim for a fasting triglyceride level at or below 150 mg/dL remains unchanged.
Sandeep B, et al. Fasting compared with nonfasting triglycerides and risk of cardiovascular events in women. JAMA. 2007;298:309-316.
McBride P. Trigylcerides and risk for coronary heart disease. JAMA. 2007;298:336-338.