Gender differences in diurnal triglyceridemia in lean and overweight subjects.

AIMS: Increased fasting and postprandial triglyceridemia is one of the cardiovascular risk factors for patients with insulin resistance. Since triglyceride (TG) metabolism largely depends on gender, we have investigated diurnal TG changes in patients with and without overweight, focusing on gender differences. METHODS: Twenty-two males and 22 females with overweight (mean body mass index (BMI) 28.0+/-2.3 kg/m2) measured capillary TG concentrations at six fixed time points on three different days. Diurnal TG profiles were calculated as area under the capillary TG curves (TGc-AUCs). The control group consisted of 24 males and 21 females who were not overweight (mean BMI 22.4+/-1.5 kg/m2). Biochemical and anthropometric parameters associated with insulin resistance were measured. RESULTS: Lean males and lean females had comparable fasting insulin levels (6.9+/-2.6 and 8.1+/-4.7 mU/l, respectively), but females had a more favorable fasting lipoprotein profile when compared to males. Diurnal TG profiles were lower in lean females than in lean males (16.9+/-4.3 vs 20.3+/-5.7 mMh, respectively, P<0.05). Overweight males and females had comparable fasting insulin levels (10.3+/-3.4 and 12.1+/-4.9 mU/l, respectively), which were higher than in lean subjects. Overweight females also had a more favorable fasting lipoprotein profile compared to overweight males. Diurnal TG profiles were similar in overweight females and overweight males (31.1+/-15.6 and 32.9+/-13.2 mMh, respectively). Stepwise multiple regression analysis showed that in both males and females, waist circumference was the strongest determinant of diurnal TG profiles when fasting TG concentrations were excluded from the model (R2=0.49 for males and R2=0.33 for females). These results suggest that overweight resulted in a 'male diurnal TG profile' in females due to abdominal fat accumulation. CONCLUSION: Insulin resistance in overweight subjects partly mitigates the gender differences of fasting and postprandial TG metabolism. The significant positive association between diurnal triglyceridemia and waist circumference supports the view that especially abdominal fat associated with insulin resistance enhances postprandial lipemia.