Abstract 5527: Validation of a Novel Combined Oral Triglyceride Tolerance Test/Glucose Tolerance Test
Background: The importance of postprandial triglyceride (TG) metabolism on cardiovascular risk has not been studied prospectively. Large epidemiologic studies suggest a close association of postprandial TG levels with the risk of cardiovascular events, whereas fasting TG levels were not predictive after multivariate analysis. The aim of our study was to develop a combined oral triglyceride and glucose tolerance test (OTTT/OGTT) in order to investigate postprandial triglyceride and glucose tolerance at the same time in prospective studies.
Methods and Results: 23 healthy volunteers (age 25 ± 1y) were given 75g fat (whipping cream) alone or in combination with 75g dextrose (simultaneously or with dextrose given 3 hours after the cream). The metabolic provocation tests were well tolerated by all subjects. Following the OTTT, TG levels increased from 90 ± 14 to maximally 171 ± 28mg/dl (p<0.05) 3 hours after the ingestion. Cholesterol (total, LDL, HDL), glucose and insulin levels remained unchanged. Simultaneous application of OTTT and OGTT led to a marked loss of the TG peak in hours 3–5 (max. 149 ± 14mg/dl at 2 hours, p<0.05). Blunting of the maximal TG increase was attributed to an insulin-mediated activation of lipoprotein lipase (basal insulin level: 5.8 ± 0.6μIU/ml; maximum insulin level 34 ± 5.6μIU/ml, p<0.01). However, changing the protocol to a sequential application of the glucose 3 hours after the oral fat load test, the original triglyceride curve was restored (basal: 100 ± 13.7mg/dl; 163 ± 22.5mg/dl, peak at 3h after ingestion, p<0.01). This sequential protocol was prospectively compared with the OTTT alone in 120 patients with stable coronary artery disease (n=60 per group). The TG levels did not differ between groups (Seq. test: 137 ± 6.9mg/dl at baseline, max. 245 ± 13.6mg/dl; OTTT: 137 ± 8.7mg/dl at baseline, max. 250 ± 14.7mg/dl) showing that combination with the OGTT does not alter TG kinetics in this sequential protocol.
Conclusions: The results of this pilot study confirm that TG tolerance and glucose tolerance can be measured within 5 hours by utilizing a novel, simple and cost-effective sequential test which can be used to asses the importance of TG tolerance for cardiovascular events in a prospective study.