餐后高甘油三酯血症与冠心病的关系

为探讨餐后高甘油三酯血症与冠心病的关系 ,6 1例研究对象被分为冠心病组 (n =30 )和对照组 (n =31)两组 ,均口服标准脂肪餐 (含脂肪 5 3.4g/m2 体表面积 ) ,分别测定其空腹及餐后 2、4、6、8及 10h的甘油三酯浓度及高密度脂蛋白胆固醇浓度。发现两组病人餐后甘油三酯浓度达高峰时间均为 6h ,冠心病组的高峰浓度 (6 .15±3.0 0mmol/L)及餐后甘油三酯代谢的曲线下面积 [2 5 .96± 14.33mmol/ (h·L) ]明显高于对照组 [4 .5 9± 2 .0 9mmol/L及 14.6 9± 6 .5 8mmol/ (h·L) ,P <0 .0 0 5 ]。Logistic多元回归分析提示 ,餐后甘油三酯代谢的曲线下面积是冠心病的独立危险因素。相关分析表明餐后甘油三酯代谢的曲线下面积与两组餐后 6h及 8h甘油三酯浓度存在明显的正相关关系。以上提示冠心病病人存在异常的餐后高甘油三酯血症 ,该异常是冠心病的独立危险因素。测定餐后 6h及 8h甘油三酯浓度可以代替餐后甘油三酯代谢的曲线下面积 ,从而简化脂肪餐负荷试验。     

原发性高血压患者脂餐后甘油三酯代谢异常与颈动脉内中膜复合体厚度的关系

为探讨原发性高血压患者是否存在脂肪负荷后血清富含甘油三酯脂蛋白代谢异常及其与颈动脉内中膜复合体厚度之间的关系 ,选择 38例原发性高血压患者和 30例健康人 (对照组 ) ,禁食 10～ 12h后 ,采用二维血管超声测定双侧颈动脉内中膜复合体厚度。随后进行标准脂肪负荷试验 ,分别以甘油三酯 8h曲线下面积和甘油三酯峰反应作为脂肪负荷后甘油三酯反应水平的指标。发现 :①原发性高血压组甘油三酯峰反应 (4.6 8± 1.74mmol L比 1.76± 0 .6 4mmol L)及甘油三酯曲线下面积 (2 3.5 9± 6 .4 8mmol L比 9.5 6± 3.38mmol L ,8h)显著大于对照组 (P<0 .0 5 ) ;②原发性高血压组颈动脉内中膜复合体厚度显著大于对照组 (0 .76 7± 0 .15mm比 0 .6 0 3± 0 .0 5mm ,P <0 .0 1) ;③原发性高血压患者的颈动脉内中膜复合体厚度与甘油三酯曲线下面积、年龄、甘油三酯峰反应、肥胖指数呈正相关 (r=0 .4 97、0 .4 4 8、0 .382、0 .35 2 ,P <0 .0 5 ) ,同空腹高密度脂蛋白水平呈负相关 (r =- 0 .2 87,P =0 .0 0 2 )。提示原发性高血压患者存在脂餐后甘油三酯代谢异常 ,高血压和餐后甘油三酯代谢异常均与颈动脉内中膜复合体厚度的增加有关。     

Vildagliptin therapy reduces postprandial intestinal triglyceride-rich lipoprotein particles in patients with type 2 diabetes

Aims/hypothesis We assessed the effects of vildagliptin, a novel dipeptidyl peptidase IV inhibitor, on postprandial lipid and lipoprotein metabolism in patients with type 2 diabetes.Subjects, materials and methods This was a single-centre, randomised, double-blind study in drug-naive patients with type 2 diabetes. Patients received vildagliptin (50 mg twice daily, n=15) or placebo (n=16) for 4 weeks. Triglyceride, cholesterol, lipoprotein, glucose, insulin, glucagon and glucagon-like peptide-1 (GLP-1) responses to a fat-rich mixed meal were determined for 8 h postprandially before and after 4 weeks of treatment.Results Relative to placebo, 4 weeks of treatment with vildagliptin decreased the AUC_0–8h for total trigyceride by 22±11% (p=0.037), the incremental AUC_0–8h (IAUC_0–8h) for total triglyceride by 85±47% (p=0.065), the AUC_0–8h for chylomicron triglyceride by 65±19% (p=0.001) and the IAUC_0–8h for chylomicron triglyceride by 91±28% (p=0.002). This was associated with a decrease in chylomicron apolipoprotein B-48 (AUC_0–8h, −1.0±0.5 mg l⁻¹ h, p=0.037) and chylomicron cholesterol (AUC_0–8h, −0.14±0.07 mmol l⁻¹ h, p=0.046). Consistent with previous studies, 4 weeks of treatment with vildagliptin also increased intact GLP-1, suppressed inappropriate glucagon secretion, decreased fasting and postprandial glucose, and decreased HbA_1c from a baseline of 6.7% (change, −0.4±0.1%, p<0.001), all relative to placebo.Conclusions/interpretation Treatment with vildagliptin for 4 weeks improves postprandial plasma triglyceride and apolipoprotein B-48-containing triglyceride-rich lipoprotein particle metabolism after a fat-rich meal. The mechanisms underlying the effects of this dipeptidyl peptidase IV inhibitor on postprandial lipid metabolism remain to be explored.     

Effects of 12 weeks’ treatment with a proton pump inhibitor on insulin secretion, glucose metabolism and markers of cardiovascular risk in patients with type 2 diabetes: a randomised double-blind prospective placebo-controlled study

Aims/hypothesis

Recent studies suggest that proton pump inhibitor treatment may increase insulin secretion and improve glucose metabolism in type 2 diabetes. In a randomised double-blind prospective placebo-controlled 2 × 2 factorial study, we examined the effect of esomeprazole on insulin secretion, HbA_1c and cardiovascular risk factors in type 2 diabetes.

Methods

Forty-one patients with type 2 diabetes using dietary control or oral glucose-lowering treatment were randomised to receive add-on esomeprazole 40 mg (n?=?20) or placebo (n?=?21) for 12 weeks. Randomisation was carried out prior to inclusion on the basis of a computer-generated random-number list. The allocation sequence was concealed in sealed envelopes from the researcher enrolling and assessing participants. The study was undertaken at Steno Diabetes Center, Gentofte, Denmark. The primary outcome was change in AUC for insulin levels during a meal test. Secondary outcomes were the levels of HbA_1c and biochemical markers of cardiovascular risk, including lipids, coagulation factors, inflammation markers, markers of endothelial function and 24 h ambulatory BP measurements.

Results

Forty-one participants were analysed. In the esomeprazole-treated group the AUC for insulin did not change (before vs after treatment: 28,049?±?17,659 vs 27,270?±?32,004 pmol/l × min (p?=?0.838). In the placebo group AUC for insulin decreased from 27,392?±?14,348 pmol/l × min to 22,938?±?11,936 pmol/l × min (p?=?0.002). Esomeprazole treatment (n?=?20) caused a ninefold increase in the AUC for gastrin. HbA_1c increased from 7.0?±?0.6% (53?±?5 mmol/mol) to 7.3?±?0.8% (56?±?6 mmol/mol) in the esomeprazole-treated group and from 7.0?±?0.6% (53?±?5 mmol/mol) to 7.4?±?0.8% (57?±?6 mmol/mol) in the placebo group (n?=?21) (p for difference in change >0.05). Except for BP, there were no differences between the groups in the markers of cardiovascular risk (p?>?0.05). Monitoring of 24 h ambulatory BP showed a significant decrease in daytime systolic BP, daytime diastolic BP and 24 h diastolic BP in the placebo group (p?<?0.05). No change in BP was seen in the patients treated with esomeprazole.

Conclusions/interpretation

Treatment with esomeprazole over 12 weeks did not improve insulin secretion, glycaemic control or cardiovascular disease biomarkers in patients with type 2 diabetes.

Trial registration

ClinicalTrials.gov NCT00699426

Funding

The study was funded by Novo Nordisk A/S and Christian Hansen A/S.     

Extended-release Niacin Acutely Suppresses Postprandial Triglyceridemia

ObjectivePostprandial triglyceridemia predicts cardiovascular events. Niacin might lower postprandial triglycerides by restricting free fatty acids. Immediate-release niacin reduced postprandial triglycerides, but extended-release niacin failed to do so when dosed the night before a fat challenge. The study aims were to determine whether extended-release niacin dosed before a fat challenge suppresses postprandial triglycerides and whether postprandial triglycerides are related to free fatty acid restriction.MethodsA double-blinded, placebo-controlled, random-order crossover experiment was performed, in which healthy volunteers took 2 g extended-release niacin or placebo 1 hour before heavy cream. We sampled blood over 12 hours and report triglycerides and free fatty acid as means ± standard deviation for incremental area under the curve (AUC) and nadir.ResultsBy combining 43 fat challenges from 22 subjects, postprandial triglycerides incremental AUC was +312 ± 200 mg/dL*h on placebo versus +199 ± 200 mg/dL*h on extended-release niacin (33% decrease, P = .02). The incremental nadir for free fatty acid was ?0.07 ± 0.15 mmol/L on placebo versus ?0.27 ± 0.13 mmol/L on extended-release niacin (P < .0001), and free fatty acid incremental AUC decreased from +2.9 ± 1.5 mmol/L*h to +1.5 ± 1.5 mmol/L*h on extended-release niacin (20% decrease, P = .0015). The incremental AUC for triglycerides was strongly related to the post-dose decrease in free fatty acid (r = +0.58, P = .0007).ConclusionsGiven right before a fat meal, even a single dose of extended-release niacin suppresses postprandial triglyceridemia. This establishes that postprandial triglycerides suppression is an acute pharmacodynamic effect of extended-release niacin, probably the result of marked free fatty acid restriction. Further study is warranted to determine whether mealtime dosing would augment the clinical efficacy of extended-release niacin therapy.     

Relationship between altered postprandial lipemia and insulin resistance in normolipidemic and normoglucose tolerant obese patients

OBJECTIVE: Although there are changes in the postprandial lipid responses of obese patients, these are closely associated with high fasting triglycerides (TG). This study of 17 normotriglyceridemic, normoglucose-tolerant android obese subjects (body mass index, BMI = 34.3 +/- 3.1 kg/m2) and 33 normal-weight controls (BMI = 21.8 +/- 1.6 kg/m2) was done to examine their postprandial responses to an oral fat loading test containing retinol (890 calories, 85% fat) and to evaluate the possible association between clinical and biological features of obesity and/or insulin resistance and postprandial lipemia. SUBJECTS AND MEASUREMENTS: Blood samples were taken before giving the fat load and at 2,3,4,5,6 and 8 h after it. Insulin sensitivity was assessed using HOMA, and TG and retinyl palmitate (RP) in the plasma, chylomicrons and non-chylomicron fractions were measured each time. RESULTS: The areas under the curves (AUC) of chylomicron TG for the obese and controls were not different, indicating adequate lipolytic activity. By contrast, the AUC for non-chylomicron TG was significantly greater in the obese than in the controls (512 +/- 135 vs 429 +/- 141 mmol/lmin, P < 0.01). In addition, the AUC for RP in this same fraction was significantly lower in the obese than in the controls (103 +/- 55 vs 157 +/- 88 mg/l min, P < 0.05), suggesting that the TG from endogenous lipoproteins accounted for most of the increase in TG in the non chylomicron fraction. Parameters related to obesity showed no relationship with these postprandial abnormalities, whereas HOMA, which discriminated between the groups, partly explained (r2= 23%, P < 0.01) the significant increase in non-chylomicron TG. CONCLUSIONS: Android obese patients with a fasting TG in the normal range and not different from the fasting TG of lean controls had an abnormal postprandial lipemia response, indicated by a significantly greater TG in the non-chylomicron subfraction than in controls. These alterations may be partly due to postprandial changes in endogenous lipoproteins as a consequence of insulin resistance.     

A randomised trial of enteric-coated nutrient pellets to stimulate gastrointestinal peptide release and lower glycaemia in type 2 diabetes

Aims/hypotheses

Glucagon-like peptide-1 (GLP-1), an important mediator of postprandial glycaemia, could potentially be stimulated by delivering small quantities of nutrient to a long length of distal gut. We aimed to determine whether enteric-coated pellets, releasing small amounts of lauric acid throughout the ileum and colon, could reduce glycaemic responses to meals in type 2 diabetes, associated with stimulation of GLP-1.

Methods

Eligible patients, who had type 2 diabetes controlled by diet or metformin, were each studied on two occasions in a hospital setting. After an overnight fast, patients consumed 5 g active pellets (47% lauric acid by weight) or placebo with breakfast (T?=?0 min) and lunch (T?=?240 min), in a crossover design with order randomised by the hospital pharmacy and allocation concealed by numbered containers. Patients and investigators making measurements were blinded to the intervention. Blood was sampled frequently for blood glucose (the primary outcome) and hormone assays.

Results

Eight patients were randomised (four to receive either intervention first), and all completed the study without adverse effects. Blood glucose was lower after breakfast (T?=?0–240 min, area under the curve (AUC) 2,075?±?368 vs 2,216?±?163 mmol/l?×?min) and lunch (T?=?240–480 min, AUC 1,916?±?115 vs 2,088?±?151 mmol/l?×?min) (p?=?0.02 for each) after active pellets than after placebo. Plasma GLP-1 concentrations were higher after breakfast (p?=?0.08) and lunch (p?=?0.04) for active pellets. While there were no differences in insulin or glucose-dependent insulinotropic polypeptide concentrations, glucagon concentrations were higher after breakfast and lunch (p?=?0.002 for each) for active pellets.

Conclusions/interpretation

Delivering small amounts of nutrient to the ileum and colon can stimulate substantial endogenous GLP-1 release and attenuate postprandial glycaemia. This novel approach has therapeutic potential in type 2 diabetes.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12612000600842.

Funding

The study was funded by Meyer Nutriceuticals.     

Postprandial chylomicrons and adipose tissue lipoprotein lipase are altered in type 2 diabetes independently of obesity and whole-body insulin resistance

Background and aimsPostprandial lipoprotein abnormalities in type 2 diabetes are associated with insulin resistance. The role of other diabetes-related factors is still not clear. The aim of this study is to differentiate the effects of whole-body insulin resistance, obesity, and type 2 diabetes on postprandial dyslipidaemia and lipoprotein lipase (LPL) in adipose tissue.Methods and resultsTen subjects with obesity and diabetes (OD), 11 with obesity alone (O), and 11 normal-weight controls (C) – males, aged 26–59 years, with fasting normo-triglyceridaemia underwent measurements of cholesterol, triglycerides, apo B-48 and apo B-100 concentrations in plasma lipoproteins separated by density gradient ultracentrifugation before and after a fat-rich meal. Fasting and postprandial (6 h) LPL activity was determined in abdominal subcutaneous adipose tissue biopsy samples. Insulin sensitivity was measured by hyperinsulinaemic euglycaemic clamp. OD and O subjects had similar degrees of adiposity (BMI, waist circumference, fat mass) and insulin resistance (insulin stimulated glucose disposal and M/I). They also showed a similarly higher postprandial increase in large VLDL lipids (triglyceride incremental AUC 188 ± 28 and 135 ± 22 mg/dl·6 h) than C (87 ± 13 mg/dl·6 h, M ± SEM, p < 0.05). OD had an increased chylomicron response compared to O (triglyceride incremental AUC 132 ± 23 vs. 75 ± 14 mg/dl·6 h, p < 0.05). OD had significantly lower fasting and postprandial adipose tissue heparin-releasable LPL activity than O and C.ConclusionsIn insulin-resistant conditions of obesity, with and without diabetes, large VLDL are increased after a fat-rich meal. In addition, diabetic patients compared to obese subjects have an increased postprandial chylomicron response and a reduced adipose tissue LPL activity.     

Delayed chylomicron remnant clearance in subjects with heterozygous familial hypercholesterolaemia

Castro Cabezas M, De Bruin TWA, Westerveld HE, Meijer E, Erkelens DW (Departments of Internal Medicine and Endocrinology, University Hospital Utrecht and University Hospital Maastricht, The Netherlands). Delayed chylomicron remnant clearance in subjects with heterozygous familial hypercholesterolaemia. J Intern Med 1998; 244 : 299–307.

Objectives

To study the role of the LDL receptor in the clearance of chylomicron remnants in humans.

Design

Chylomicron remnant clearance was studied in five untreated subjects with heterozygous familial hypercholesterolaemia (FH) and nine normolipidaemic controls, by oral retinyl palmitate-fat loading tests. Fasting plasma triglycerides (TG), which are important determinators of chylomicron and remnant clearance, were not significantly different between FH (1.76 ± 0.32 mmol L^?1, mean ± SEM) and controls (1.26 ± 0.18 mmol L^?1). Chylomicrons (Sf > 1000) and their remnants (Sf < 1000) were separated by flotation and their clearance was estimated by calculating the area under the 24 h-retinyl palmitate curve (AUC-RP). The factors determining chylomicron and remnant clearance were studied by univariate and multiple regression analysis.

Results

Triglyceride clearance in plasma, Sf > 1000 fractions and Sf < 1000 fractions was not significantly different between FH subjects and controls. In subjects with heterozygous FH, chylomicron remnant clearance was two-fold delayed (AUC-RP, 49.39 ± 11.61 h.mg L^?1) compared to controls (27.45 ± 3.95 h.mg L^?1; P= 0.048). Moreover, 28.4% higher fasting plasma TG in FH resulted in 44.4% higher areas under the remnant-curves compared to controls. The clearance of chylomicron RP was associated to plasma apo E (β= 0.73, P= 0.011), plasma LDL cholesterol (β= 0.62, P= 0.018) and plasma TG (β= 0.58, P= 0.029). The clearance of remnant RP was associated to the diagnosis (FH vs. non-FH), but not to the well-known determinants of remnant clearance like plasma TG.

Conclusions

The clearance of chylomicrons and large remnants isolated in the Sf > fraction depends primarily on the apo B, E (LDL) receptor and to a lesser extent on plasma triglycerides. The clearance of smaller chylomicron remnants isolated in the Sf < 1000 depends to a large extent on the apo B, E (LDL) receptor.

     

Liraglutide changes postprandial responses of gut hormones involved in the regulation of gallbladder motility

Aim

Liraglutide treatment is associated with gallbladder-related disorders and has been shown to delay postprandial gallbladder refilling. The gut hormones cholecystokinin (CCK), fibroblast growth factor 19 (FGF19) and glucagon-like peptide 2 (GLP-2), are known to regulate gallbladder motility and may be implicated in gallbladder-related disorders associated with liraglutide treatment.

Materials and Methods

In a double-blind, 12-week trial, 52 participants [50% male, age 47.6 ± 10.0 years, body mass index 32.6 ± 3.4 kg/m² (mean ± standard deviation)] with obesity were randomized 1:1 to once-daily subcutaneous liraglutide (escalated from 0.6 mg to 3.0 mg once-daily) or placebo. During liquid meal tests performed at baseline, after the first dose and following 12 weeks of treatment, we evaluated postprandial gallbladder dynamics and plasma responses of CCK, FGF19 and GLP-2.

Results

Liraglutide reduced postprandial FGF19 after the first dose [area under the curve (AUC)_{0-240 min} 24.8 vs. 48.0 min × ng/ml, treatment ratio (TR) (95% confidence interval) 0.52 (0.39; 0.69)] and following 12 weeks of treatment [AUC_{0-240 min} 33.7 vs. 48.5 ng/ml × min, TR 0.69 (0.52; 0.93)]. Liraglutide also reduced postprandial GLP-2 responses (AUC_{0-240 min} 3650 vs. 4894 min × pmol/L, TR 0.75 (0.62; 0.90)] following the first dose as well as after 12 weeks [AUC_{0-240 min} 3760 vs. 4882 min × pmol/L, TR 0.77 (0.60; 0.99)]. Liraglutide increased postprandial responses of CCK after the first dose [AUC_{0-240 min} 762 vs. 670 min × pmol/L; TR 1.14 (0.97; 1.33)] and following 12 weeks of treatment [AUC_{0-240 min} 873 vs. 628 min × pmol/L; TR 1.39 (1.12; 1.73)].

Conclusion

Compared with placebo, treatment with liraglutide decreased postprandial FGF19 and GLP-2 concentrations and increased postprandial CCK concentrations, which may explain the delayed postprandial gallbladder refilling observed in individuals with obesity treated with liraglutide.     

Postprandial apolipoprotein B48-and B100-containing lipoproteins in type 2 diabetes: do statins have a specific effect on triglyceride metabolism?

There is little information about the effect of an alteration of low-density lipoprotein (LDL) turnover on chylomicron and very-low-density lipoprotein (VLDL) metabolism, yet chylomicron remnant particles are thought to be particularly atherogenic. This study examined the effect of inhibition of cholesterol synthesis on postprandial lipoproteins. Eight type 2 diabetic patients were examined before treatment with the 3-hydroxy-3-methyl glutaryl coenzyme A (HMGCoA) reductase inhibitor cerivastatin, after 4 weeks on active treatment, and 4 weeks after stopping treatment. On each occasion, blood was collected fasting and at 2-hour intervals for up to 8 hours after a high-fat meal. Chylomicrons and VLDLs were isolated by sequential ultracentrifugation. Compositional analysis was performed including the measurement of apolipoprotein B48 (apo B48) and apo B100 using polyacrylamide gradient gel electrophoresis. During statin treatment, there was a significant reduction in the postprandial chylomicron apo B48 area under the curve (AUC) from 23 +/- 16 to 17 +/- 10 (P < .01) and apo B100 in the chylomicron fraction from 166 +/- 148 to 70 +/- 70 (P < .05). Postprandial cholesterol (362 +/- 193 to 74 +/- 39, P < .005), triglyceride (2,222 +/- 1,440 to 746 +/- 329), and phospholipid (518 +/- 267 to 205 +/- 94) also decreased (P < .005). In the VLDL fraction, the postprandial cholesterol and triglyceride AUC were significantly reduced by statin (316 +/- 228 to 171 +/- 78, P < .05, and 1,733 +/- 833 to 857 +/- 468, P < .02, respectively). Four weeks after cessation of treatment, the chylomicron fraction triglyceride AUC had returned to the pretreatment level, but postprandial chylomicron cholesterol and VLDL cholesterol, triglyceride, and phospholipid were significantly lower than baseline (P < .05). Plasma total cholesterol and LDL cholesterol were significantly reduced with treatment (6.2 +/- 0.5 to 4.3 +/- 1.0 mmol/L, P < .001, and 4.5 +/- 0.4 to 2.8 +/- 1.0 mmol/L, P < .01, respectively) and returned to baseline following cessation of treatment. Fasting plasma triglycerides decreased significantly on treatment (2.4 +/- 1.0 to 1.7 +/- 0.2 mmol/L, P < .05) but remained significantly lower than baseline 4 weeks later (1.8 +/- 0.3 mmol/L, P < .05). This study suggests major postprandial lipoprotein changes on statin therapy which may account, in part, for the beneficial effects of statins in the prevention of myocardial infarction.     

Menopause is associated with reduced protection from postprandial lipemia

Deficiency of endogenous estrogens has been associated with a higher incidence of coronary heart disease (CHD) in women. We investigated whether natural menopause is associated with reduced protection from postprandial lipemia, which represents a risk indicator of CHD. Twenty-three postmenopausal women (mean age, 50+/-1 [SD] years; body mass index, 24.6+/-2.8 kg/m(2)) and 21 premenopausal women matched for age and body mass index (age, 49+/-1 years; body mass index, 24. 1+/-2.6 kg/m(2)) underwent an oral vitamin A fat-loading test. Vitamin A is a marker of the metabolism of chylomicrons and chylomicron remnants. All women were normolipidemic, were in good health, were nonsmokers, and used no medication. Postprandial lipids and vitamin A were measured at hourly intervals up to 12 hours. In postmenopausal women, plasma total cholesterol and LDL cholesterol concentrations were significantly higher. Fasting plasma triglyceride (TG) concentrations were 1.14+/-0.57 mmol/L in postmenopausal women and 0.88+/-0.33 mmol/L in premenopausal women (P=NS). In the postprandial phase, postmenopausal women had higher plasma TG (13.0+/-6.1 versus 9.5+/-3.3 mmol x L(-1) x h(-1); P=0.024) and vitamin A (54.1+/-22.9 versus 35.9+/-9.6 mg x L(-1) x h(-1); P=0. 001) responses. To correct for the possible confounding effect of fasting TG, 13 postmenopausal women were carefully matched with 19 premenopausal women. Although fasting TG levels were identical (0. 72+/-0.20 versus 0.73+/-0.21 mmol/L), differences in postprandial vitamin A (45.3+/-14.5 versus 33.0+/-7.7 mg x L(-1) x h(-1); P=0.006) and incremental TG (ie, after subtraction of baseline TG) (3.2+/-1.8 versus 2.3+/-1.0 mmol x L(-1) x h(-1); P=0.023) persisted between postmenopausal and premenopausal women. Natural menopause is associated with aggravated postprandial lipemia in women matched for age and body mass index. Higher postprandial lipemia potentially explains the relation of TGs and CHD mortality risk in postmenopausal women.     

Very low density lipoprotein subfractions in Type II diabetes mellitus: alterations in composition and susceptibility to oxidation

Aims/hypothesis. Type II (non-insulin-dependent) diabetes mellitus is associated with raised triglycerides and increased very low density lipoprotein cholesterol. The aim of this study was to assess if very low density lipoprotein subfraction composition and potential to oxidise were altered in this condition.¶Methods. Very low density lipoprotein was separated into four subfractions (A→D) by a novel, rapid ultracentrifugation procedure. Analysis of each subfraction included lipid and fatty acid composition. Preformed peroxides were measured spectrophotometrically and conjugated dienes were used as an indicator of in vitro lipid oxidation.¶Results. In all results we compared patient and control subfractions. Mean fasting plasma glucose was 8.9 ± 2.0 mmol/l in patients vs 5.1 ± 0.4 mmol/l in control subjects (p < 0.001); patient HbA_{1 c} was 7.6 ± 1.4 %. Patient total lipid standardised for apo B was higher than controls in subfractions A, B and C; A, 201 vs 60; B, 191 vs 40; C, 63 vs 21; D, 29 vs 34 μmol lipid per mg apo B (p < 0.05). Preformed peroxides were higher in all patient subfractions compared with controls: A, 340 vs 48; B, 346 vs 42; C, 262 vs 28; D, 54 vs 16 nmol per mg apo B (p < 0.001). Patient subfractions A and D were more susceptible to in vitro oxidation. Monounsaturated fatty acids were lower in patients subfractions, 35.2 vs 36.7; B, 35.1 vs 38.7; C, 34.4 vs 36.5; D, 33.0 vs 35.5 as per cent total (p < 0.05).¶Conclusions/interpretation. These results indicate abnormalities in very low density lipoprotein subfraction composition and oxidation profile in Type II diabetic subjects, which are characteristic of more atherogenic particles and that may contribute to the development of cardiovascular disease in these patients. [Diabetologia (2000) 43: 485–493]     

Metabolic heterogeneity underlying postprandial lipemia among men with low fasting high density lipoprotein cholesterol concentrations

The high triglyceride (TG) and low high density lipoprotein (HDL) cholesterol dyslipidemia has been associated with increased postprandial lipemia. Although fasting TG is a powerful predictor of postprandial hyperlipidemia, the role of hypoalphalipoproteinemia in postprandial TG metabolism is uncertain. We have studied postprandial lipemia among 63 men with low fasting plasma HDL cholesterol concentrations (<0.9 mmol/L), but with either low (<2.0 mmol/L) or high (>2.0 mmol/L) fasting plasma TG levels. A significant relationship was noted between postprandial TG response and fasting HDL cholesterol concentration (r = -0.43; P: < 0.0005). We also found that men with high TG/low HDL dyslipidemia (high TG and low HDL cholesterol; n = 16) were characterized by abdominal obesity as well as increased visceral adipose tissue accumulation, whereas normolipidemic controls (low TG and high HDL cholesterol; n = 26) and men with isolated low HDL cholesterol concentrations (low TG and low HDL cholesterol; n = 17) were not characterized by features of the insulin resistance syndrome (visceral obesity, hyperinsulinemia, and hypertriglyceridemia). Although controls and men with isolated low HDL cholesterol levels had similar postprandial lipemic responses, men with the high TG/low HDL dyslipidemia had a marked increase in their postprandial TG responses to the fat load compared with the other subgroups (P: < 0. 001). Men with the high TG/low HDL dyslipidemia were also characterized by higher concentrations of apolipoprotein (apo) B-48 and B-100 particles (chylomicron remnants and very low density lipoproteins, respectively) before and during the postprandial period compared with the other subjects. These results suggest that low HDL cholesterol concentration is a heterogeneous metabolic phenotype that it is not associated with postprandial hyperlipidemia unless accompanied by other features of the insulin resistance syndrome.     

Heterogeneous Postprandial Lipoprotein Responses in the Metabolic Syndrome, and Response to Fenofibrate Therapy

Background

Hypertriglyceridemia subjects with metabolic syndrome exhibit variable postprandial triglyceride responses. We investigate the effects of fenofibrate therapy on postprandial triglyceride-containing lipoproteins in subjects with early (3.5 h) versus late (8 h) postprandial triglyceride responses.

Methods

Fifty-five subjects with fasting hypertriglyceridemia (≥1.7 mmol/L (150 mg/ dL) and <5.8 mmol/L (500 mg/dL)) and ≥2 Adult Treatment Panel III criteria of the metabolic syndrome were randomized to daily fenofibrate (160 mg/d) or placebo for 12 weeks in a double-blind controlled clinical trial. A standardized fat load (50 g/m²) was given orally after a 12 h fast. Blood specimens were obtained at 0 h (fasting), 3.5 h, and 8 h after the test meal. Analysis is confined to the 53 subjects with clearly identifiable early or late triglyceride peaks prior to therapy.

Results

Fenofibrate was more effective in late peakers (n?=?8) when compared to early peakers (n?=?15) with respect to reducing postprandial triglyceride concentrations (?67% vs. ?34%, p?=?0.0024) and large VLDL (?76% vs. ?31%, p?=?0.0016), and increasing total HDL particles (20% vs. 11%, p?=?0.008) and large HDL particles (185% vs. 88%, p?=?0.003). On fenofibrate therapy, 100% of those initially designated as late peakers were reclassified as early peakers; 47% of late peakers assigned to placebo were reclassified as early peakers.

Conclusions

Late postprandial triglyceride responders have attenuated clearance of large VLDL particles, but they were more responsive to fenofibrate.     

Efficacy and tolerability of vildagliptin in drug-naïve patients with type 2 diabetes and mild hyperglycaemia*

Aim: This study was conducted to assess efficacy and tolerability of vildagliptin in drug‐naïve patients with type 2 diabetes and mild hyperglycaemia. Methods: Multicentre, double‐blind, randomized, placebo‐controlled, parallel‐group study of 52‐week treatment with vildagliptin (50 mg q.d.) in 306 drug‐naïve patients with type 2 diabetes (A1C = 6.2–7.5%). A1C, fasting plasma glucose (FPG) and measures of prandial glucose control and beta‐cell function determined during standard meal tests were assessed. Results: Baseline A1C and FPG averaged 6.7% and 7.1 mmol/l, respectively, in patients randomized to vildagliptin (n = 156) and 6.8% and 7.2 mmol/l in those randomized to placebo (n = 150). A1C decreased modestly in vildagliptin‐treated patients (Δ = ?0.2 ± 0.1%) and increased in patients receiving placebo (Δ = 0.1 ± 0.1%). The between‐group difference (vildagliptin ? placebo) in adjusted mean change (AMΔ) in A1C was ?0.3 ± 0.1% (p < 0.001). FPG increased in patients receiving placebo (Δ = 0.5 ± 0.1 mmol/l) and to a significantly lesser extent in vildagliptin‐treated patients (between‐group difference in AMΔ FPG = ?0.4 ± 0.2 mmol/l, p = 0.032). Relative to placebo, 2‐h postprandial glucose (PPG) decreased (?0.9 ± 0.4 mmol/l, p = 0.012), and insulin secretory rate (ISR) relative to glucose [ISR area under the curve (AUC)_{0–2 h}/glucose AUC_{0–2 h}] increased (+5.0 ± 1.2 pmol/min/m²/mM, p < 0.001). Mean body weight decreased by 0.5 ± 0.3 kg in vildagliptin‐treated patients and by 0.2 ± 0.3 kg in patients receiving placebo. The side‐effect profile of vildagliptin was similar to that of placebo, and one hypoglycaemic episode occurred in one patient receiving placebo. Conclusions: In drug‐naïve patients with mild hyperglycaemia, relative to placebo, 52‐week treatment with vildagliptin 50 mg q.d. significantly decreases A1C, FPG and PPG and improves beta‐cell function without weight gain or hypoglycaemia.     

Apolipoprotein E enrichment of immuno-separated chylomicron and chylomicron remnants following saturated fatty acids

AimWe examined the effect of meal fatty acids on lipid and apolipoprotein concentrations of very low density lipoprotein (VLDL) and chylomicron/chylomicron remnants in lipid fractions with a Svedberg flotation rate (S_f) 60–400 and S_f 20–60.Methods and resultsSix healthy middle-aged men received in random order mixed meals enriched with saturated (SFA), polyunsaturated (PUFA) or monounsaturated (MUFA) fatty acids on 3 occasions. VLDL and chylomicron/chylomicron remnants in the lipid fractions were separated by immunoaffinity chromatography against apo B-100. In the S_f 60–400 chylomicron/chylomicron remnants, triacylglycerol and cholesterol concentrations were significantly lower following PUFA compared with SFA and MUFA (P ≤ 0.05). Apolipoprotein (apo) E responses were significantly higher after SFA in chylomicron/chylomicron remnants and VLDL compared with PUFA and MUFA (P < 0.007). However, apo B responses (particle number) were higher following MUFA than SFA (P = 0.039 for chylomicron/chylomicron remnants). Composition of the chylomicron/chylomicron remnants (expressed per particle) revealed differences in their triacylglycerol and apo E contents; in the S_f 60–400 fraction, SFA-rich chylomicron/chylomicron remnants contained significantly more triacylglycerol than MUFA (P = 0.028), more apo E than PUFA- and MUFA-rich particles (P < 0.05) and in the S_f 20–60 fraction, more apo E than MUFA (P = 0.009).ConclusionThere are specific differences in the composition of chylomicron/chylomicron remnants formed after saturated compared with unsaturated fatty acid-rich meals which could determine their metabolic fate in the circulation and subsequent atherogenicity.     

‘Exercise snacks’ before meals: a novel strategy to improve glycaemic control in individuals with insulin resistance

Aims/hypothesis

The aim of this study was to investigate whether small doses of intense exercise before each main meal (‘exercise snacks’) would result in better blood glucose control than a single bout of prolonged, continuous, moderate-intensity exercise in individuals with insulin resistance.

Methods

Nine individuals completed three exercise interventions in randomised order. Measures were recorded across 3 days with exercise performed on the middle day, as either: (1) traditional continuous exercise (CONT), comprising 30 min moderate-intensity (60% of maximal heart rate [HR_max]) incline walking before dinner; (2) exercise snacking (ES), consisting of 6?×?1 min intense (90% HR_max) incline walking intervals 30 min before each meal; or (3) composite exercise snacking (CES), encompassing 6?×?1 min intervals alternating between walking and resistance-based exercise, 30 min before meals. Meal timing and composition were controlled within participants for exercise interventions.

Results

ES attenuated mean 3 h postprandial glucose concentration following breakfast (by 1.4?±?1.5 mmol/l, p?=?0.02) but not lunch (0.4?±?1.0 mmol/l, p?=?0.22), and was more effective than CONT following dinner (0.7?±?1.5 mmol/l below CONT; p?=?0.04). ES also reduced 24 h mean glucose concentration by 0.7?±?0.6 mmol/l (p?=?0.01) and this reduction persisted for the subsequent 24 h (lower by 0.6?±?0.4 mmol/l vs CONT, relative to their baselines; p?=?0.01). CES was just as effective as ES (p?>?0.05 for all glycaemic variables) at improving glycaemic control.

Conclusions/interpretation

Dosing exercise as brief, intense ‘exercise snacks’ before main meals is a time-efficient and effective approach to improve glycaemic control in individuals with insulin resistance.     

Postprandial hyperlipidemia: another correlate of the "hypertriglyceridemic waist" phenotype in men

Fasting hypertriglyceridemia has been reported to be predictive of an exaggerated triglyceride (TG) response to an oral fat load. Abdominal obesity has also been associated with postprandial hyperlipidemia. The objective of the present study was to quantify the contribution of abdominal obesity and fasting hypertriglyceridemia to the magnitude of postprandial lipemia. For that purpose, potential differences in postprandial TG-rich lipoprotein (TRL) levels were examined among men characterized by the absence/presence of the "hypertriglyceridemic waist" phenotype following a standardized breakfast with a high fat content (64% calories as fat). Sixty-nine men (mean age +/- S.D.: 45.1 +/- 10.5 years) were classified according to waist girth (< 90 or >/ or = 90 cm) and fasting TG concentrations (< 2.0 or > or = 2.0 mmol/l). Subjects characterized by "hypertriglyceridemic waist" (waist > or = 90 cm and fasting TG > or = 2.0 mmol/l) showed the highest TRL-TG concentrations (P < 0.0001) throughout the entire postprandial period (8 h) as well as elevated concentrations of apolipoprotein (apo) B-48 and apo B-100 in all TRL fractions (large, medium and small) compared to subjects with low fasting TG levels who had waist girth values either above or below 90 cm. These higher postprandial TRL-TG levels among carriers of the "hypertriglyceridemic waist" phenotype also led to significantly greater postprandial TG-total area under the curve (AUC) in total TRLs resulting mainly from the increased concentrations of large- and medium-sized TRLs. Furthermore, subjects characterized by the "hypertriglyceridemic waist" phenotype displayed higher fasting insulin concentrations and postprandial insulin AUC compared to men with low fasting plasma TG levels and low waist girth values. In conclusion, results of the present study indicate that postprandial hyperlipidemia is associated with the simultaneous presence of abdominal obesity and elevated fasting TG concentrations: a condition that we have described as the "hypertriglyceridemic waist" phenotype.     

Determinants of glucose tolerance in impaired glucose tolerance at baseline in the Actos Now for Prevention of Diabetes (ACT NOW) study

Aims/hypothesis

The aim of the study was to examine the determinants of oral glucose tolerance in 602 persons with impaired glucose tolerance (IGT) who participated in the Actos Now for Prevention of Diabetes (ACT NOW) study.

Methods

In addition to the 602 IGT participants, 115 persons with normal glucose tolerance (NGT) and 50 with impaired fasting glucose (IFG) were identified during screening and included in this analysis. Insulin secretion and insulin sensitivity indices were derived from plasma glucose and insulin during an OGTT. The acute insulin response (AIR) (0–10 min) and insulin sensitivity (S_I) were measured with the frequently sampled intravenous glucose tolerance test (FSIVGTT) in a subset of participants.

Results

At baseline, fasting plasma glucose, 2 h postprandial glucose (OGTT) and HbA_1c were 5.8?±?0.02 mmol/l, 10.5?±?0.05 mmol/l and 5.5?±?0.04%, respectively, in participants with IGT. Participants with IGT were characterised by defects in early (?I _0–30/?G _0–30?×?Matsuda index, where ?I is change in insulin in the first 30 min and ?G is change in glucose in the first 30 min) and total (?I_0–120/?G_0–120?×?Matsuda index) insulin secretion and in insulin sensitivity (Matsuda index and S_I). Participants with IGT in whom 2 h plasma glucose was 7.8–8.3 mmol/l had a 63% decrease in the insulin secretion/insulin resistance (disposition) index vs participants with NGT and this defect worsened progressively as 2 h plasma glucose rose to 8.9–9.94 mmol/l (by 73%) and 10.0–11.05 mmol/l (by 80%). The Matsuda insulin sensitivity index was reduced by 40% in IGT compared with NGT (p?<?0.005). In multivariate analysis, beta cell function was the primary determinant of glucose AUC during OGTT, explaining 62% of the variance.

Conclusion

Our results strongly suggest that progressive beta cell failure is the main determinant of progression of NGT to IGT.