Diurnal triglyceride profiles in healthy normolipidemic male subjects are associated to insulin sensitivity, body composition and diet

BACKGROUND: Elevated fasting and postprandial triglycerides (TG) are established risk factors for Coronary Heart Disease (CHD). Usually, fasting plasma TG are measured, although TG are mainly produced in a postprandial state. Our objective was to investigate diurnal TG profiles using serial capillary TG measurements, in normolipidemic healthy males. MATERIALS AND METHODS: Forty-eight, non-obese, non-smoking males (range: 20-55 years, mean age: 32 +/- 12 years), measured diurnal capillary TG, at six fixed timepoints during the day on three different days and recorded their food intake. Insulin sensitivity was estimated by HOMA. Diurnal capillary TG profiles were calculated as integrated area under the mean capillary TG curve (TGc-AUC). RESULTS: All subjects had normal fasting plasma TG and cholesterol. The average TGc-AUC was 23.6 +/- 6.7 mmol h L-1. Significant correlations with TGc-AUC were: fasting insulin (r = 0. 40, P < 0.005), HOMA (r = 0.32, P < 0.05), relative fat mass (r = 0. 31, P < 0.05), dietary protein-(r = 0.31, P < 0.05) and saturated fat intake (r = 0.30, P < 0.05). Age was not associated to diurnal triglyceridemia. After subdividing the group into quartiles on the base of TGc-AUC, differences were found between the highest (n = 12) and lowest quartile (n = 12) for: fasting capillary TG, fasting insulin, HOMA and systolic blood pressure. Fasting plasma TG and dietary intake were not different. CONCLUSION: Diurnal TG profiles in healthy normolipidemic males are not age-dependent, but are associated to insulin sensitivity, fat mass and diet. Diurnal capillary TG profiles may be a valuable additional tool in estimating a risk profile for CHD since significant differences in diurnal TG are not always reflected by elevated fasting plasma TG.