Triglyceride Excursions Research Articles

Double-Blind Randomized Clinical Trial of the Effects of Ezetimibe on Postprandial Hyperlipidaemia and Hyperglycaemia

Ezetimibe selectively blocks intestinal cholesterol absorption by inhibiting Niemann-Pick C1-like 1 (NPC1L1) and reducing LDL cholesterol (LDL-C). In animals, ezetimibe reversed diet-induced obesity, liver steatosis, and insulin resistance. In humans, its potential effects on liver steatosis and insulin resistance have been suggested. We investigated the effects of ezetimibe on postprandial hyperlipidaemia and hyperglycaemia in obese subjects with dyslipidaemia in a double-blind randomized crossover trial. Twenty obese men with hypertriglyceridaemia were assigned randomly to an ezetimibe- or a placebo-precedence-treated group. Subjects in the ezetimibe group were treated with ezetimibe (10 mg/day) for the first 4 weeks, followed by a 4-week interval and then treated with placebo for another 4 weeks. The placebo group received these treatments in reverse order. Subjects were requested to fast for at least 12 hours and then received a standard meal. Blood samples were collected at 0, 30, 60, 120, 240, 360 and 480 minutes after the meal on Days 0, 28, 56 and 84 and were used to measure the lipid and glucose metabolism markers. Ezetimibe significantly decreased the postprandial serum triglyceride excursion (p=0.01) and fasting serum LDL-C, remnant-like particles(RLP) and ApoB48 levels (p<0.05). Postprandial glucose excursion, serum insulin levels, serum glucose-dependent insulinotropic polypeptide (GIP) and active glucagon-like peptide-1 (GLP-1) were not significantly affected by ezetimibe treatment. Ezetimibe restored the postprandial dysregulation of lipid but did not affect glucose metabolism in a double-blind randomized crossover trial.

Angptl4 deficiency decreases serum triglyceride levels in low-density lipoprotein receptor knockout mice and streptozotocin-induced diabetic mice

Angiopoietin-like protein family 4 (Angptl4) has been shown to regulate lipoprotein metabolism through the inhibition of lipoprotein lipase (LPL). In familial hypercholesterolemia (FH), individuals lacking low-density lipoprotein receptor (LDLR) present not only hypercholesterolemia, but also increased plasma triglyceride (TG)-rich lipoprotein remnants, and develop atherosclerosis. In addition, the most common type of dyslipidemia in individuals with diabetes is increased TG levels. We first generated LDLR −/−Angptl4 −/− mice to study the effect of Angptl4 deficiency on the lipid metabolism. Fasting total cholesterol, VLDL-C, LDL-C, HDL-C and TG levels were decreased in LDLR −/−Angptl4 −/− mice compared with LDLR −/−Angptl4 +/+ mice. In particular, post olive oil-loaded TG excursion were largely attenuated in LDLR −/−Angptl4 −/− mice compared with LDLR −/−Angptl4 +/+ mice. We next introduced diabetes by streptozotocin (STZ) treatment in Angptl4 −/− mice and examined the impacts of Angptl4 deficiency. Compared with diabetic Angptl4 +/+ mice, diabetic Angptl4 −/− mice showed the improvement of fasting and postprandial hypertriglyceridemia as well. Thus, targeted silencing of Angptl4 offers a potential therapeutic strategy for the treatment of dyslipidemia in individuals with FH and insulin deficient diabetes.

Leptin increases skeletal muscle lipoprotein lipase and postprandial lipid metabolism in mice

The ability of leptin to preserve lean tissue during weight loss may be in part due to differences in nutrient partitioning. Because lipoprotein lipase (LPL) plays a key role in partitioning lipid nutrients, this study was conducted to test the hypothesis that leptin would modify the tissue-specific regulation of LPL and result in increased lipid oxidation and decreased storage. The effects of daily intraperitoneal leptin injections (2 mg/kg body weight) over 2 weeks on LPL activity and postprandial lipid metabolism were tested in both wild-type (WT), leptin-deficient ob/ob obese mice and mice pair fed to the leptin-treated mice. On the experimental day, mice were given food by gavage, blood was drawn periodically, and adipose tissue and skeletal muscle were harvested for measurements of LPL activity at 240 minutes. After 2 weeks of leptin administration, skeletal muscle LPL (SMLPL) activity was increased in leptin-treated compared with pair-fed ( P = .012) and WT ( P = .002) mice. There was no effect of leptin or pair feeding on postprandial adipose tissue LPL activity. In ob/ob mice, leptin treatment normalized the decrease in postprandial free fatty acid concentration ( P = .066). Leptin had no effect on either the area under the triglyceride (TG) excursion or the integrated area under the TG excursion in WT mice. In ob/ob mice, however, the TG excursion was lower in the leptin-treated than the pair-fed mice by area under the TG excursion ( P = .012) and was lower than in the WT mice by integrated area under the TG excursion ( P = .027). As expected, 2 weeks of leptin treatment decreased body weight in both the WT and ob/ob mice (−2.6% and −10.4%, respectively). Leptin treatment increased SMLPL, an effect that may have contributed to the leptin-induced weight loss. The leptin-induced decreased postprandial TG excursion in ob/ob mice suggests that leptin acts to augment clearance of postprandial TG-rich lipoprotein lipid and that this increase may in part be secondary to the increased activity of SMLPL. The trend for decreased postprandial free fatty acid may indicate that leptin decreases adipose tissue lipid stores without increasing lipolysis.

One-year treatment with exenatide vs. Insulin Glargine: Effects on postprandial glycemia, lipid profiles, and oxidative stress

ObjectiveThe objective of the present study was to investigate the effects of one-year treatment with exenatide or Insulin Glargine, followed by a 5-week off-drug period, on postprandial lipidaemia, glycaemia and measures of oxidative stress. MethodsSixty-nine metformin-treated patients with type 2 diabetes were randomised (using apermuted block randomisation scheme stratified by site and baseline HbA1c stratum (≤8.5% or >8.5%) of which 60 completed (exenatide n=30; Insulin Glargine n=30) the pre-treatment and on-drug meal test. Postprandial glucose, lipids and lipoproteins, and oxidative stress markers were studied at week −1, 51, and after a 5-week off-drug period following a breakfast and lunch mixed-meal containing 50g fat, 75g carbohydrates, and 35g protein. Results51-Week exenatide treatment resulted in a significant reduction of prandial glucose, triglycerides, apo-B48, calculated VLDL-C, FFA and MDA excursions whereas Insulin Glargine predominantly reduced fasting glucose, FFA and MDA. Changes in markers of oxidative stress were related to changes in postprandial glucose and triglyceride excursions, independent of treatment arm. All postprandial measures returned to pre-treatment values in both groups after 5-week cessation of study treatment. ConclusionExenatide showed beneficial effects on postprandial glycaemia and lipidaemia, and these effects were related to changes in the oxidative stress markers MDA and oxLDL during one year of treatment as compared to Insulin Glargine. Following cessation of both exenatide and Insulin Glargine measures returned to pre-treatment values, suggesting that ongoing treatment is necessary to maintain the beneficial effects of either therapy.

In vivo efficacy of acyl CoA: Diacylglycerol acyltransferase (DGAT) 1 inhibition in rodent models of postprandial hyperlipidemia

Postprandial serum triglyceride concentrations have recently been identified as a major, independent risk factor for future cardiovascular events. As a result, postprandial hyperlipidemia has emerged as a potential therapeutic target. The purpose of this study was two-fold. Firstly, to describe and characterize a standardized model of postprandial hyperlipidemia in multiple rodent species; and secondly, apply these rodent models to the evaluation of a novel class of pharmacologic agent; acyl CoA:diacylglycerol acyltransferase (DGAT) 1 inhibitors. Serum triglycerides were measured before and for 4h after oral administration of a standardized volume of corn oil, to fasted C57BL/6, ob/ob, apoE(-/-) and CD-1 mice; Sprague-Dawley and JCR/LA-cp rats; and normolipidemic and hyperlipidemic hamsters. Intragastric administration of corn oil increased serum triglycerides in all animals evaluated, however the magnitude and time-course of the postprandial triglyceride excursion varied. The potent and selective DGAT-1 inhibitor A-922500 (0.03, 0.3 and 3 mg/kg, p.o.), dose-dependently attenuated the maximal postprandial rise in serum triglyceride concentrations in all species tested. At the highest dose of DGAT-1 inhibitor, the postprandial triglyceride response was abolished. This study provides a comprehensive characterization of the time-course of postprandial hyperlipidemia in rodents. In addition, the ability of DGAT-1 inhibitors to attenuate postprandial hyperlipidemia in multiple rodent models, including those that feature insulin resistance, is documented. Exaggerated postprandial hyperlipidemia is inherent to insulin-resistant states in humans and contributes to the substantially elevated cardiovascular risk observed in these patients. Therefore, by attenuating postprandial hyperlipidemia, DGAT-1 inhibition may represent a novel therapeutic approach to reduce cardiovascular risk.

Comparison of Postprandial Responses to a High-Fat Meal in Hypertriglyceridemic Men and Women before and after Treatment with Fenofibrate in the Genetics and Lipid Lowering Drugs and Diet Network (GOLDN) Study.

The fenofibrate effect on the subclass size distribution of lipoproteins before and after a high-fat challenge is not well studied. To characterize the baseline and post-prandial response (PPL) to a high-fat challenge following fenofibrate therapy, on changes in LDL, HDL, and VLDL particle subclasses, number, and size in 271 hypertriglyceridemic participants. Participants from the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study who conducted PPL studies both before and after three weeks of fenofibrate (160 mg/d) treatment were analyzed. Particle size distributions were determined using nuclear magnetic resonance imaging, and lipid determinations were measured at fasting (0 hr), 3.5 hours, and 6 hours after ingestion of a standardized high-fat meal. Analyses were stratified by gender. Changes in particle subclass distributions were assessed using repeated measures analysis of variance adjusted for pedigree. Before PPL, fenofibrate in men (adjusted for age, field center, smoking status, diabetes, and weight circumference) lowered fasting and postprandial VLDL primarily due to reductions in postprandial levels of large and medium VLDL particles (9 SE +/-0.7 to 4 +/-0.4 and 78 / -4 to 36 / -3 nmol/L both P < .0001, resp.). Fenofibrate also reduced fasting and postprandial total LDL particles, primarily a result of reduced small LDL particles (1497 = / - 37 to 1088 = / - 36 nmol/L, P < .0001). Directional changes were similar in men and women but the magnitude of change was different for some parameters. Fenofibrate treatment resulted in a lower triglyceride excursion following a high-fat meal. This investigation provides new knowledge of the magnitude and time course of fenofibrate induced attenuation of Lipoprotein subclass size distribution following a postprandial lipid challenge.

Determinants of postprandial triglyceride and glucose responses after two consecutive fat-rich or carbohydrate-rich meals in normoglycemic women and in women with type 2 diabetes mellitus: the Hoorn Prandial Study

Both postprandial hyperglycemia and hypertriglyceridemia have been identified as risk markers for cardiovascular disease, but parameters associated with these postprandial responses are largely unknown. The objective was to assess whether usually measured clinical and biochemical parameters can predict postprandial glucose and triglyceride responses and whether these responses are associated with each other. Postmenopausal women, 76 with normal glucose metabolism (NGM) and 41 with type 2 diabetes mellitus (T2DM), received 2 consecutive fat-rich meals and carbohydrate-rich meals on separate occasions. Blood samples were taken before and at t = 1, 2, 4, 6, and 8 hours after breakfast; lunch was given at t = 4 hours. Regression analysis was performed with incremental area under the postprandial triglyceride curve (triglyceride-iAUC) and glucose curve (glucose-iAUC) after fat-rich and carbohydrate-rich meals, respectively. In women with NGM, fasting triglycerides, hemoglobin A 1c, total cholesterol, and, inversely, high-density lipoprotein cholesterol were independently associated with triglyceride-iAUC; and age and fasting triglycerides were independently associated with glucose-iAUC. In women with T2DM, fasting triglycerides were independently associated with triglyceride-iAUC, whereas hemoglobin A 1c and fasting glucose were stronger than fasting triglycerides associated with glucose-iAUC. Glucose-iAUC and triglyceride-iAUC were associated with each other in women with T2DM, but not in those with NGM. The association between glucose-iAUC and triglyceride-iAUC in women with T2DM and the association of fasting triglycerides with both glucose-iAUC and triglyceride-iAUC in NGM and T2DM suggest a common underlying mechanism for postprandial increments in glucose and triglycerides, especially in T2DM. Commonly measured clinical and biochemical parameters can only partly explain postprandial glucose and triglyceride excursions.

P.7.a.003 Biogenetic temperament and character and attention deficit hyperactivity symptoms in Korean preschool children

The objective of the present study was to investigate the effects of one-year treatment with exenatide or Insulin Glargine, followed by a 5-week off-drug period, on postprandial lipidaemia, glycaemia and measures of oxidative stress.Sixty-nine metformin-treated patients with type 2 diabetes were randomised (using apermuted block randomisation scheme stratified by site and baseline HbA1c stratum (≤8.5% or >8.5%) of which 60 completed (exenatide n = 30; Insulin Glargine n = 30) the pre-treatment and on-drug meal test. Postprandial glucose, lipids and lipoproteins, and oxidative stress markers were studied at week −1, 51, and after a 5-week off-drug period following a breakfast and lunch mixed-meal containing 50 g fat, 75 g carbohydrates, and 35 g protein.51-Week exenatide treatment resulted in a significant reduction of prandial glucose, triglycerides, apo-B48, calculated VLDL-C, FFA and MDA excursions whereas Insulin Glargine predominantly reduced fasting glucose, FFA and MDA. Changes in markers of oxidative stress were related to changes in postprandial glucose and triglyceride excursions, independent of treatment arm. All postprandial measures returned to pre-treatment values in both groups after 5-week cessation of study treatment.Exenatide showed beneficial effects on postprandial glycaemia and lipidaemia, and these effects were related to changes in the oxidative stress markers MDA and oxLDL during one year of treatment as compared to Insulin Glargine. Following cessation of both exenatide and Insulin Glargine measures returned to pre-treatment values, suggesting that ongoing treatment is necessary to maintain the beneficial effects of either therapy.

Effect of exenatide on 24-hour blood glucose profile compared with placebo in patients with type 2 diabetes: A randomized, double-blind, two-arm, parallel-group, placebo-controlled, 2-week study

Objective: The aim of this study was to examine the glucose-lowering effect of exenatide over 24 hours in patients with type 2 diabetes with inadequate glycemic control using metformin, with or without a thiazolidinedione (TZD). Methods: This randomized, double-blind, 2-arm, parallel-group, placebo-controlled, 2-week study was conducted in patients with type 2 diabetes with inadequate glycemic control, despite metformin with or without a TZD. Patients underwent a baseline and a week-2 (study end) 24-hour admission during which serial serum glucose measurements were taken. Preprandial and postprandial concentrations of triglycerides and free fatty acids were also measured. Meals provided for each patient were identical at the baseline and week-2 assessments. Following the baseline admission, patients were randomized to receive SC injections of either exenatide (5 μg BID for 1 week, then 10 μg BID for the next week) or placebo (volume equivalent) for 14 days. Results: A total of 30 patients (19 women [63%], 11 men [37%]; mean [SD] age, 52.6 [11.2] years; weight, 94.3 [23.0] kg; body mass index, 34.2 [6.1] kg/m 2; glycosylated hemoglobin value, 8.0% [0.9%]; diabetes duration, 8.7 [5.6] years; race, Hispanic 18 [60%], white 10 [33%], black 2 [7%]) were eligible. Seventeen patients (57%) were randomized to treatment with exenatide and 13 patients (43%) received placebo. Concurrent antidiabetic medications were metformin only (n = 19 [63%]) and metformin plus a TZD (n = 11 [37%]). All postbaseline values were least squares mean (SE). After 2 weeks (study end), the 24-hour time-average glucose values were 7.0 (0.2) and 8.8 (0.3) mmol/L for exenatide-treated and placeboadministered patients, respectively ( P < 0.001). The glucose values for patients treated with exenatide were lower compared with those in patients who received placebo 2 hours after the morning meal (6.6 [0.4] vs 12.0 [0.5] mmol/L; P < 0.001), the midday meal (8.8 [0.5] vs 11.8 [0.6] mmol/L; P = 0.001), and the evening meal (6.8 [0.4] vs 11.3 [0.4] mmol/L; P < 0.001). The mean durations of patient exposure to glucose concentrations >7.8 and >11.1 mmol/L were significantly shorter for the exenatide group compared with the placebo group (>7.8 mmol/L: 6.8 [0.9] vs 14.1 [1.1] hours; >11.1 mmol/L: 1.0 [0.7] vs 4.7 [0.8] hours; both, P < 0.001). After 2 weeks, the postprandial triglyceride excursions after the morning and evening meals for patients treated with exenatide were significantly lower compared with those treated with placebo. There was no apparent effect on free fatty acid concentrations. Conclusions: In these patients with type 2 diabetes, exenatide was associated with significantly reduced glucose concentrations at multiple time points during 24 hours, with the greatest effect seen on postprandial glucose concentrations. In addition, exenatide was associated with decreased overall hyperglycemic exposure and significantly decreased postprandial triglyceride excursions. These results are consistent with those seen in other studies that reported the effectiveness of exenatide in controlling hyperglycemia in patients with type 2 diabetes.

The genetic response to short-term interventions affecting cardiovascular function: Rationale and design of the Heredity and Phenotype Intervention (HAPI) Heart Study

The etiology of cardiovascular disease (CVD) is multifactorial. Efforts to identify genes influencing CVD risk have met with limited success to date, likely because of the small effect sizes of common CVD risk alleles and the presence of gene by gene and gene by environment interactions. The HAPI Heart Study was initiated in 2002 to measure the cardiovascular response to 4 short-term interventions affecting cardiovascular risk factors and to identify the genetic and environmental determinants of these responses. The measurements included blood pressure responses to the cold pressor stress test and to a high salt diet, triglyceride excursion in response to a high-fat challenge, and response in platelet aggregation to aspirin therapy. The interventions were carried out in 868 relatively healthy Amish adults from large families. The heritabilities of selected response traits for each intervention ranged from 8% to 38%, suggesting that some of the variation associated with response to each intervention can be attributed to the additive effects of genes. Identifying these response genes may identify new mechanisms influencing CVD and may lead to individualized preventive strategies and improved early detection of high-risk individuals.

Effect of Morning Exercise on Daily Post-prandial Triglcerides

PURPOSE: An increased post-prandial triglyceride (PPTG) excursion is an independent risk factor for coronary heart disease, therefore, evaluating factors that increase or decrease this parameter is important. Women reportedly have a lower PPTG after a single meal compared to men whereas moderate exercise decreases PPTG after consumption of a single, very high fat meal. The aims of this study, therfore, were to a) determine if a single bout of morning exercise can significantly decrease PPTGs over an entire day, when consuming meals of a more typical macronutrient composition and b) to determine if there is a sex difference in the daily PPTG excursion with and/or without exercise. METHODS: Non-obese (BMI 20-27 kg/m2), untrained, healthy, women (n = 11) and men (n = 12) were recruited and matched for fasting TG levels (101 ± 27 and 100 ± 14 mg/dl, respectively). Subjects completed an exercise and a rest study day (randomized order) separated by 3-4 weeks. Prior to each study day, subjects consumed a controlled diet (5 days) and abstained from planned exercise (60 hrs). After an overnight stay on the clinical research unit, subjects commenced testing at 7:15 am after an overnight fast. On the exercise day, subjects walked on a treadmill for 60 mins at 60% VO2 peak and on the rest day, subjects rested for the same time period. Breakfast was consumed at 8:30 am, with lunch and dinner at 12:30 pm and 5:30 pm, respectively. Macronutrient composition of each meal was 34% fat, 15% protein and 51% carbohydrate. Subjects remained resting from 8:30 am onwards and energy intake was calculated to meet energy requirements of the corresponding day. Blood samples were drawn before exercise (or rest) and continued throughout the remainder of the day (total of 26 time points). RESULTS: The integrated area under the curve (IAUC) for total TGs over the entire day was significantly lower on the exercise vs rest day in both women (7766 ± 2977 vs 22947 ± 2979 mg/dl/840 mins, respectively P < 0.0001) and men (20196 ± 5660 vs 29721 ± 5252 mg/dl/840 mins). There was an overall significant sex difference in the daily PPTG excursion (IAUC, P = 0.05), mainly due to the lower response in women vs men on the exercise day (P = 0.07). In both sexes, the difference in the PPTG excursion on the exercise vs rest day was greatest after lunch (P = 0.0003 women, P = 0.03 men) and dinner (P < 0.0001 and P = 0.05, respectively). There were no sex or day differences in the daily insulin and glucose excursions. CONCLUSIONS: In conclusion, a single bout of moderate exercise can reduce the daily PPTG response when consuming meals of a typical macronutrient composition, and this response tends to be more pronounced in women vs men.

Insulin resistance affects the regulation of lipoprotein lipase in the postprandial period and in an adipose tissue-specific manner.

Insulin is a potent stimulator of adipose tissue lipoprotein lipase (LPL). Logically, the postprandial period is therefore a privileged time of the day for the regulation of LPL by insulin in this tissue. It is not clear to what extent a defect such as insulin resistance could affect this regulation and contribute to postprandial, as well as fasting, hypertriglyceridaemia. The aim of the present protocol was to study the relationship between insulin resistance and LPL in adipose tissue and in plasma, in the particular context of the postprandial period. For this study, 26 adult nondiabetic individuals (12 women and 14 men) with a wide range of whole-body insulin-mediated glucose uptake (as assessed with an insulin suppression test) were studied. An abdominal subcutaneous fat biopsy on one occasion, and post-heparin plasma on another occasion, were obtained 4 h into a standardized meal profile administered in the fasting state. Postprandial triglyceride excursions (evaluated by the incremental area under the curve during the metabolic meal profile) were inversely correlated to adipose tissue LPL mRNA levels (rho = -0.43, P < 0.03) as well as to adipose tissue LPL heparin-releasable activity (rho = -0.58, P < 0.01). Steady-state plasma glucose (SSPG) concentrations during the insulin suppression test, a reflection of the degree of insulin resistance, were also negatively correlated to adipose tissue LPL mRNA (rho = -0.50, P < 0.02) and activity (rho = -0.56, P < 0.01). There was no correlation between plasma post-heparin LPL activity/mass and postprandial triglycerides nor with insulin resistance. Regulation of adipose tissue LPL is significantly affected in insulin-resistant individuals in the postprandial period. This presumed impaired effect of insulin on LPL postprandially could be an important contributor to the atherogenic dyslipidaemia described in insulin resistance syndrome.