The reliability of an abbreviated fat tolerance test: A comparison to the oral glucose tolerance test

Background & aims: Postprandial lipemia (PPL) is predictive of cardiovascular disease risk, but the current method for assessing PPL is a burdensome process. Recently, the validity of an abbreviated fat tolerance test (AFTT) has been demonstrated. As a continuation of this research, the purpose of this study was to determine the reliability of the AFTT and compare it to the reliability of the oral glucose tolerance test (OGTT).

Methods: In this randomized crossover trial, 20 healthy adults (10 male and 10 female) completed 2 AFTTs and 2 OGTTs, each separated by a 1-week washout. For the AFTT, triglycerides (TG) were measured at baseline and 4 h post-consumption of a high-fat meal, during which time participants were able to leave the lab. For the OGTT, we measured blood glucose at baseline and 2 h post-consumption of a 75-g pure glucose solution, and participants remained in the lab. To determine reliability, we calculated within-subject coefficient of variation (WCV) and intraclass correlation coefficient (ICC).

Results: The mean 4-h TG WCV for the AFTT was 12.6%, while the mean 2-h glucose WCV for the OGTT was 10.5%. ICC values for 4-h TG and TG change were 0.79 and 0.71, respectively, while ICC values for 2-h glucose and glucose change were 0.66 and 0.56, respectively.

Conclusions: Based on WCV and ICC, the TG response to an AFTT was similarly reliable to the glucose response to an OGTT in our sample of healthy adults, supporting the AFTT's potential as a standard clinical test for determining PPL. However, reliability of the AFTT needs to be further tested in individuals at greater risk for cardiometabolic disease.