Diurnal triglyceridaemia and insulin resistance in mildly obese subjects with normal fasting plasma lipids

. Objective.  A novel method has been developed to study diurnal triglyceride (TG) profiles using repeated capillary self-measurements in an ‘out-of-hospital’ situation. We assessed the diurnal capillary TG (TGc) profile in males with mild obesity and evaluated the use of plasma and capillary TG as markers of insulin resistance. Design.  Cross-sectional study. Setting and Subjects.  Fifty-four lean (body mass index, BMI < 25 kg m−2) and 27 mildly obese (25 < BMI < 30 kg m−2), normolipidaemic males measured capillary TG concentrations on six fixed time-points over a 3-day period in an ‘out-of-hospital’ situation. Main outcome measures.  The total area under the TGc curve (TGc-AUC) and incremental area under the TGc curve (TGc-IAUC) were used as estimation of diurnal triglyceridaemia. Fasting blood samples were obtained once. Food intake was recorded by all participants. Results.  Obese and lean subjects had comparable fasting capillary TG concentrations (1.37 ± 0.40 mmol L−1 and 1.32 ± 0.53 mmol L−1, respectively). However, during the day, obese subjects showed a greater TG increase, resulting in significantly higher TGc-AUC (27.1 ± 8.4 and 23.0 ± 6.3 mmol h−1 l−1, respectively; P < 0.05) and TGc-IAUC (7.9 ± 5.8 and 4.6 ± 6.6 mmolh−1 L−1, respectively; P < 0.05). The total group of 81 males was divided into quartiles based on fasting plasma TG, fasting capillary TG, TGc-AUC and TGc-IAUC. Amongst these variables, TGc-AUC was the only significant discriminator of subjects with high homeostasis model assessment (HOMA) (insulin resistance) compared with low HOMA (insulin sensitive). Overall, BMI was the strongest determinant of HOMA. Conclusions.  Diurnal TG profiles can be used to investigate postprandial lipaemia in both lean and mildly obese subjects and may help to detect subjects with an underlying disposition for hypertriglyceridaemia related to insulin resistance, i.e. the metabolic syndrome.