Insulin Resistance Is Independently Associated With Postprandial Alterations of Triglyceride-Rich Lipoproteins in Type 2 Diabetes Mellitus

Postprandial Triglyceride, Glucose and Insulin Levels 10 Years After Bariatric Surgery in Women With Severe Obesity - A Pilot Study: Part 2 - Biliopancreatic Diversion

Obesity significantly increases the risk of developing metabolic and cardiovascular diseases. The most effective management tool for both obesity and type 2 diabetes (T2D) is bariatric/metabolic surgery. Delayed postprandial plasma triglyceride clearance contributes to the development of atherosclerosis in patients with T2D. Biliopancreatic diversion (BPD) was shown to be the most effective procedure in long-term T2D remission. However, the effect of BPD on postprandial metabolic profile has not been studied so far. In this pilot study, we therefore examined the changes in postprandial glucose, insulin, and triglyceride in women with severe obesity and T2D before surgery and then two and ten years after BPD. The studied cohort included 7 women (mean age at baseline=49.3±8.2 years) with severe obesity (mean BMI= 45.7±2.9 kg/m?) and T2D. A standardized liquid mixed-meal test was carried out in all subjects and the mean postprandial levels of plasma glucose, insulin, and triglyceride were analyzed by standard laboratory procedures. For statistical evaluation, ANOVA with Bonferroni multiple comparisons was used. Ten years after BPD not only a significant reduction of an average BMI (F=32.9, p<0.001) but also significant declines in mean postprandial plasma levels of glucose (F=155.3, p<0.001), insulin (F=69.8, p<0.001), and triglyceride (F=139.9, p<0.001) were demonstrated. The observed changes in postprandial metabolic profile may contribute to improved cardiometabolic health after bariatric surgery.

Metabolic fingerprinting on retinal pigment epithelium thickness for individualized risk stratification of type 2 diabetes mellitus

The retina is an important target organ of diabetes mellitus, with increasing evidence from patients and animal models suggesting that retinal pigment epithelium (RPE) may serve as an early marker for diabetes-related damages. However, their longitudinal relationship and the biological underpinnings remain less well understood. Here, we demonstrate that reduced in vivo measurements of RPE thickness (RPET) represents a significant risk factor for future type 2 diabetes mellitus (T2DM) and its microvascular phenotypes. After performing systematic analyses of circulating plasma metabolites using two complementary approaches, we identify a wide range of RPET metabolic fingerprints that are independently associated with reduced RPET. These fingerprints hold their potential to improve predictability and clinical utility for stratifying future T2DM and related microvascular phenotypes beyond traditional clinical indicators, providing insights into the promising role of retinas as a window to systemic health.

Correlation of Triglyceride-Rich Lipoprotein Cholesterol and Diabetes Mellitus in Stroke Patients

BACKGROUND

Previous studies have revealed that triglyceride-rich lipoprotein cholesterol (TRL-c) is closely related to diabetes mellitus (DM) in hypertensive patients. However, this relationship in stroke patients has not been reported. The aims of this study are to investigate the relationship between TRL-c and diabetes in adult Chinese stroke.

METHODS

Patients with stroke treated in the Department of Neurology of the Second Affiliated Hospital of Nanchang University from January 2019 to January 2021 were selected. TRL-c was calculated from total cholesterol minus (high-density and low-density lipoprotein). DM was diagnosed based on previous medical history (diagnosed by secondary hospitals or above) and/or current use of hypoglycemic drugs and/or intravenous blood glucose measurement (fasting blood glucose ≥7.0 mmol/L or nonfasting blood glucose > 11.1 mmol/L). The relationship between the TRL-c and DM was determined using multivariate logistic regression, smoothing curve fitting (penalized spline method), and subgroup analysis.

RESULTS

A total of 890 patients with stroke (age, 66.1 ± 11.8 years) were enrolled, including 329 females. Multivariate logistic regression analysis demonstrated that TRL-c had a positive association with DM (OR 1.88; 95% CI: 1.22 to 2.89). Strong linear associations of TRL-c with DM were confirmed by restricted cubic spline analysis. And the association between TRL-c and DM was consistent in the different subgroups.

CONCLUSION

Positive associations were found between TRL-c and DM in patients with stroke.

Apolipoprotein E content of VLDL limits LPL-mediated triglyceride hydrolysis

High levels of circulating triglycerides (TGs), or hypertriglyceridemia, are key components of metabolic diseases, such as type 2 diabetes, metabolic syndrome, and CVD. As TGs are carried by lipoproteins in plasma, hypertriglyceridemia can result from overproduction or lack of clearance of TG-rich lipoproteins (TRLs) such as VLDLs. The primary driver of TRL clearance is TG hydrolysis mediated by LPL. LPL is regulated by numerous TRL protein components, including the cofactor apolipoprotein C-II, but it is not clear how their effects combine to impact TRL hydrolysis across individuals. Using a novel assay designed to mimic human plasma conditions in vitro, we tested the ability of VLDL from 15 normolipidemic donors to act as substrates for human LPL. We found a striking 10-fold difference in hydrolysis rates across individuals when the particles were compared on a protein or a TG basis. While VLDL TG contents moderately correlated with hydrolysis rate, we noticed substantial variations in non-apoB proteins within these particles by MS. The ability of LPL to hydrolyze VLDL TGs did not correlate with apolipoprotein C-II content, but it was strongly inversely correlated with apolipoprotein E (APOE) and, to a lesser extent, apolipoprotein A-II. Addition of exogenous APOE inhibited LPL lipolysis in a dose-dependent manner. The APOE3 and (particularly) APOE4 isoforms were effective at limiting LPL hydrolysis, whereas APOE2 was not. We conclude that APOE on VLDL modulates LPL activity and could be a relevant factor in the pathogenesis of metabolic disease.

Fasting, non-fasting and postprandial triglycerides for screening cardiometabolic risk

Fasting triacylglycerols have long been associated with cardiovascular disease (CVD) and other cardiometabolic conditions. Evidence suggests that non-fasting triglycerides (i.e. measured within 8 h of eating) better predict CVD than fasting triglycerides, which has led several organisations to recommend non-fasting lipid panels as the new clinical standard. However, unstandardised assessment protocols associated with non-fasting triglyceride measurement may lead to misclassification, with at-risk individuals being overlooked. A third type of triglyceride assessment, postprandial testing, is more controlled, yet historically has been difficult to implement due to the time and effort required to execute it. Here, we review differences in assessment, the underlying physiology and the pathophysiological relevance of elevated fasting, non-fasting and postprandial triglycerides. We also present data suggesting that there may be a distinct advantage of postprandial triglycerides, even over non-fasting triglycerides, for early detection of CVD risk and offer suggestions to make postprandial protocols more clinically feasible.

iNOS as a metabolic enzyme under stress conditions

Nitric oxide (NO) is a free radical acting as a cellular signaling molecule in many different biochemical processes. NO is synthesized from l-arginine through the action of the nitric oxide synthase (NOS) family of enzymes, which includes three isoforms: endothelial NOS (eNOS), neuronal NOS (nNOS) and inducible NOS (iNOS). iNOS-derived NO has been associated with the pathogenesis and progression of several diseases, including liver diseases, insulin resistance, obesity and diseases of the cardiovascular system. However, transient NO production can modulate metabolism to survive and cope with stress conditions. Accumulating evidence strongly imply that iNOS-derived NO plays a central role in the regulation of several biochemical pathways and energy metabolism including glucose and lipid metabolism during inflammatory conditions. This review summarizes current evidence for the regulation of glucose and lipid metabolism by iNOS during inflammation, and argues for the role of iNOS as a metabolic enzyme in immune and non-immune cells.

Effect of lipoprotein-associated phospholipase A2 inhibitor on insulin resistance in streptozotocin-induced diabetic pregnant rats

This paper aims to investigate the influence of lipoprotein-associated phospholipase A2 (Lp-PLA2) inhibitor, darapladib, on insulin resistance (IR) in streptozotocin (STZ)-induced diabetic pregnant rats. The rat models were divided into Control (normal pregnancy), STZ + saline (STZ-induced diabetic pregnant rats), STZ + Low-dose and STZ + High-dose darapladib (STZ-induced diabetic pregnant rats treated with low-/high-dose darapladib) groups. Pathological changes were observed by Hematoxylin-eosin (HE) and Immunohistochemistry staining. Lp-PLA2 levels were determined by enzyme-linked immunosorbent assay (ELISA). An automatic biochemical analyzer was used to measure the serum levels of biochemical indicators, and homeostatic model assessment for insulin resistance (HOMA-IR) and insulin sensitivity index (ISI) were calculated. Western blot was applied to determine levels of inflammatory cytokines. Compared with Control group, rats in the STZ + saline group were significantly decreased in body weight, the number of embryo implantation, the number of insulin positive cells and pancreatic islet size as well as the islet endocrine cells, and high-density lipoprotein (HDL-C) level, but substantially increased in Lp-PLA2, low-density lipoprotein (LDL-C), fatty acids (FFA), serum total cholesterol (TC), triglyceride (TG) levels. Moreover, the increased fasting plasma glucose (FPG) and HOMA-IR and inflammatory cytokines but decreased fasting insulin (FINS) and ISI were also found in diabetic pregnant rats. On the contrary, rats in the darapladib-treated groups were just opposite to the STZ + saline group, and STZ + High-dose group improved better than STZ + Low-dose group. Thus, darapladib can improve lipid metabolism, and enhance insulin sensitivity of diabetic pregnant rats by regulating inflammatory cytokines.

Effects of a liquid high-fat meal on postprandial lipid metabolism in type 2 diabetic patients with abdominal obesity

Background

Postprandial lipemia and lipoprotein lipase (LPL) activity play crucial roles in the pathogenesis of accelerated atherosclerosis. This study aimed to evaluate the postprandial lipid metabolism after the ingestion of a liquid high-fat meal in type 2 diabetic patients with abdominal obesity, and determine if the PvuII polymorphisms of LPL influence their postprandial lipid responses.

Methods

Serum glucose, insulin, triglycerides (TG), total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C) were measured in fasting and postprandial state at 0.5, 1, 2, 4, 6 and 8 h after a liquid high-fat meal in 51 type 2 diabetic patients with abdominal obesity, 31 type 2 diabetic patients without abdominal obesity and 39 controls. Their PvuII polymorphisms of LPL were tested in fasting.

Results

Type 2 diabetic patients with abdominal obesity had significantly higher postprandial areas under the curve (AUC) of glucose [least square mean difference (LSMD) = 30.763, 95% confidence interval (CI) = 23.071–38.455, F = 37.346, P < 0.05] and TC (LSMD = 3.995, 95% CI = 1.043–6.947, F = 3.681, P < 0.05) than controls. Postprandial AUCs for insulin, homeostasis model assessment-insulin resistance (HOMA-IR) and TG were higher (LSMD = 86.987, 95% CI = 37.421–136.553, F = 16.739, P < 0.05; LSMD = 37.456, 95% CI = 16.312–58.600, F = 27.012, P < 0.05; LSMD = 4.684, 95% CI = 2.662–6.705, F = 26.158, P < 0.05), whereas HDL-C AUC was lower (LSMD = −1.652, 95% CI = −2.685 – -0.620, F = 8.190, P < 0.05) in type 2 diabetic subjects with abdominal obesity than those without abdominal obesity. In type 2 diabetic patients with abdominal obesity, postprandial TG AUC was lower in P−/− than in P+/− (LSMD = −4.393, 95% CI = −9.278 – -0.491, F = 4.476, P < 0.05) and P+/+ (LSMD = −7.180, 95% CI = −12.319 – -2.014, F = 4.476, P < 0.05) phenotypes. Postprandial AUCs for glucose, insulin, HOMA-IR, TC and HDL-C were not different according to PvuII phenotypes.

Conclusions

Abdominal obesity exacerbates the postprandial lipid responses in type 2 diabetic patients, which partly explains the excess atherogenic risk in these patients. In addition, the presence of P+ allele could contribute to a greater postprandial TG increase in type 2 diabetic patients with abdominal obesity.

Trial registration

ChiCTR-IOR-16008435. Registered 8 May 2016.

The impact of triglycerides on glucose tolerance: Lipotoxicity revisited

Elevated plasma triglycerides (TGs) are early key features of conditions associated with a dysregulation in glucose metabolism and may predict the development of type 2 diabetes (T2D) over time. Although the acute ingestion of lipid, either mixed with or shortly before the meal, is neutral or slightly beneficial on glucose tolerance, a short-term increase in plasma TGs induced by either an i.v. lipid infusion or a high-fat diet produces a deterioration of glucose control. Accordingly, chronic lowering of plasma TGs by fibrates improves glucose homeostasis and may also prevent T2D. The chronic effects of the elevation of dietary lipid intake are less clear, particularly in humans, being the quality of fat probably more important than total fat intake. Although on the bases of the available experimental and clinical evidence it cannot be easily disentangled, with respect to elevated non-esterified fatty acids (NEFA) the relative contribution of elevated TGs to glucose homeostasis disregulation seems to be greater and also more plausible. In conclusion, although the association between elevated plasma TGs and impaired glucose tolerance is commonly considered not causative or merely a consequence of NEFA-mediated lipotoxicity, the available data suggest that TGs per se may directly contribute to disorders of glucose metabolism.

Association of Plasma Ghrelin Levels with Insulin Resistance in Type 2 Diabetes Mellitus among Saudi Subjects

BACKGROUND

Although the exact mechanism of insulin resistance (IR) has not yet been established, IR is the hallmark characteristic of type 2 diabetes mellitus (T2DM). The aim of this study was to examine the relationship between plasma ghrelin levels and IR in Saudi subjects with T2DM.

METHODS

Patients with T2DM (n=107, cases) and non-diabetic apparently healthy subjects (n=101, controls) from Saudi Arabia were included in this study. The biochemical profiles and plasma insulin levels of all subjects were analyzed, and IR was estimated using the homeostatic model assessment of insulin resistance (HOMA-IR) index. Active ghrelin levels in plasma were measured using the radioimmunoassay technique.

RESULTS

Only 46.7% (50 of 107) of the T2DM subjects had IR, including 26% (28 of 107) with severe IR (HOMA-IR ≥5), while 5.9% (six of 101) of the controls had moderate IR (3 ≤HOMA-IR <5). HOMA-IR values were not associated with age, disease duration, or gender. Importantly, T2DM itself and the co-occurrence of IR with T2DM were significantly associated with low plasma ghrelin levels. However, ghrelin levels were inversely correlated with the HOMA-IR index, body weight, and fasting plasma insulin levels, mainly in the control subjects, which was indicative of the breakdown of metabolic homeostasis in T2DM.

CONCLUSION

The prevalence of IR was relatively low, and IR may be inversely associated with plasma ghrelin levels among Saudi patients with T2DM.

Association of Whole Blood Viscosity With Metabolic Syndrome in Type 2 Diabetic Patients: Independent Association With Post-Breakfast Triglyceridemia

Background

Associations of whole blood viscosity (WBV) with metabolic syndrome (MS) have not been extensively studied in patients with type 2 diabetes.

Methods

Intrapersonal means of 12 measurements of waist circumference, blood pressure (BP) and high-density lipoprotein cholesterol and those of six measurements of fasting and post-breakfast triglycerides (TG) during 12 months were calculated in a cohort of 168 patients with type 2 diabetes. Based on these means, MS was diagnosed according to the modified National Cholesterol Education Program Adult Treatment Panel III criteria with the Asian definition of abdominal obesity. WBV was calculated from hematocrit and total serum protein concentrations by a validated formula.

Results

Diabetes patients with MS (n = 77) had higher WBV as compared to those without MS (6.38 ± 0.06 vs. 6.10 ± 0.07 cP, P = 0.004). As the number of MS components increased, WBV increased (component number 1: 6.12 ± 0.10, 2: 6.09 ± 0.10, 3: 6.37 ± 0.08, 4: 6.42 ± 0.10, 5: 6.30 ± 0.15 cP, P for trends = 0.001). Multiple regression analysis revealed that male gender, diastolic BP and post-breakfast TG were determinants of WBV independent of fasting TG, body mass index (BMI) and waist circumference (R² = 0.258).

Conclusions

Both the presence of MS and the number of MS components were associated with higher WBV in patients with type 2 diabetes. Physicians need to perform a close follow-up of type 2 diabetes patients with MS on inhibitors of sodium-glucose co-transporters 2, which may increase stroke risk associated with an increase in hematocrit and therefore blood viscosity. Post-breakfast TG was an independent determinant of WBV. Elevated WBV may represent an important confounder of the relationship between MS, postprandial hyperlipidemia and elevated cardiovascular risk in this population.

Dapagliflozin decreases small dense low-density lipoprotein-cholesterol and increases high-density lipoprotein 2-cholesterol in patients with type 2 diabetes: comparison with sitagliptin

Background

The sodium-glucose co-transporter-2 (SGLT-2) inhibitors have been reported to increase both low-density lipoprotein (LDL) and high-density lipoprotein (HDL)-cholesterol (C). This study aimed to determine how SGLT-2 inhibitors affect LDL and HDL-C subspecies.

Methods

This single center, open-label, randomized, prospective study included 80 patients with type 2 diabetes taking prescribed oral hypoglycemic agents. Patients were allocated to receive dapagliflozin (n = 40) or sitagliptin (n = 40) as add-on treatment. Fasting blood samples were collected before and 12 weeks after this intervention. Small dense (sd) LDL-C, large buoyant (lb) LDL-C, HDL2-C, and HDL3-C levels were determined using our established homogeneous assays. Statistical comparison of blood parameters before and after treatment was performed using the paired t test.

Results

Dapagliflozin and sitagliptin comparably decreased HbA1c (0.75 and 0.63%, respectively). Dapagliflozin significantly decreased body weight, systolic blood pressure, plasma triglycerides and liver transaminases, and increased adiponectin; sitagliptin did not alter these measurements. LDL-C and apolipoprotein (apo) B were not significantly changed by dapagliflozin, whereas HDL-C and apo AI were increased. Dapagliflozin did not alter concentrations of LDL-C, but sd LDL-C decreased by 20% and lb LDL-C increased by 18%. Marked elevation in lb LDL-C (53%) was observed in individuals (n = 20) whose LDL-C was elevated by dapagliflozin. However, sd LDL-C remained suppressed (20%). Dapagliflozin increased HDL2-C by 18% without affecting HDL3-C. Sitagliptin did not alter plasma lipids or lipoprotein subspecies.

Conclusions

A SGLT-2 inhibitor, dapagliflozin suppresses potent atherogenic sd LDL-C and increased HDL2-C, a favorable cardiometabolic marker. Although LDL-C levels are elevated by treatment with dapagliflozin, this was due to increased concentrations of the less atherogenic lb LDL-C. However, these findings were not observed after treatment with dipeptidyl peptidase-4 inhibitor, sitagliptin.

Trial registration UMIN Clinical Trials Registry (UMIN000020984)

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-016-0491-5) contains supplementary material, which is available to authorized users.

Effects of Multiple Sedentary Days on Metabolic Risk Factors in Free-Living Conditions: Lessons Learned and Future Recommendations

Background: Recent experimental studies in adults have demonstrated that interruptions to prolonged sitting have beneficial effects on metabolic risk factors in adults, compared to prolonged sitting. We explored the hypothesis that multiple consecutive days of predominantly prolonged sedentary time may have an unfavorable effect on the postprandial response of C-peptide, glucose, and triglycerides in free-living healthy young men.

Methods: In this explorative pilot study, healthy young men (n = 7; 18–23 years) consumed standardized mixed meals at 1 and 5 h during two experimental laboratory-sitting days, with 6 days of predominantly prolonged sedentary time in between. Serum and plasma samples were obtained hourly from 0 to 8 h for measurement of glucose, C-peptide, and triglycerides. Participant's sedentary time was monitored using an accelerometer during the prolonged sedentary days as well as during 6 normal days prior to the first laboratory day. Differences in postprandial levels were assessed using generalized estimating equations analysis. Due to the explorative nature of this study and the small sample size, p-value was set at <0.10.

Results: Overall, when expressed as % of wear time, sedentary time was 5% higher during the 6 prolonged sedentary days, which was not significantly different compared to the 6 normal days (n = 4). Following 6 prolonged sedentary days, postprandial levels of C-peptide were significantly higher than at baseline (B = 0.11; 90%CI = [0.002; 0.22]; n = 7). Postprandial levels of glucose and triglycerides were not significantly different between the 2 laboratory days.

Conclusions: Due to the relatively high sedentary time at baseline, participants were unable to increase their sedentary time substantially. Nevertheless, postprandial C-peptide levels were slightly higher after 6 prolonged sedentary days than after 6 normal days.

Postprandial Monocyte Activation in Individuals With Metabolic Syndrome

CONTEXT

Postprandial hyperlipidemia has been suggested to contribute to atherogenesis by inducing proinflammatory changes in monocytes. Individuals with metabolic syndrome (MS), shown to have higher blood triglyceride concentration and delayed triglyceride clearance, may thus have increased risk for development of atherosclerosis.

OBJECTIVE

Our objective was to examine fasting levels and effects of a high-fat meal on phenotypes of monocyte subsets in individuals with obesity and MS and in healthy controls. Design, Setting, Participants, Intervention: Individuals with obesity and MS and gender- and age-matched healthy controls were recruited. Blood was collected from participants after an overnight fast (baseline) and at 3 and 5 hours after ingestion of a high-fat meal. At each time point, monocyte phenotypes were examined by multiparameter flow cytometry.

MAIN OUTCOME MEASURES

Baseline levels of activation markers and postprandial inflammatory response in each of the three monocyte subsets were measured.

RESULTS

At baseline, individuals with obesity and MS had higher proportions of circulating lipid-laden foamy monocytes than controls, which were positively correlated with fasting triglyceride levels. Additionally, the MS group had increased counts of nonclassical monocytes, higher CD11c, CX3CR1, and human leukocyte antigen-DR levels on intermediate monocytes, and higher CCR5 and tumor necrosis factor-α levels on classical monocytes in the circulation. Postprandial triglyceride increases in both groups were paralleled by upregulation of lipid-laden foamy monocytes. MS, but not control, subjects had significant postprandial increases of CD11c and percentages of IL-1β+ and tumor necrosis factor-α+ cells in nonclassical monocytes.

CONCLUSIONS

Compared to controls, individuals with obesity and MS had increased fasting and postprandial monocyte lipid accumulation and activation.

Effects of exercise training on intrahepatic lipid content in humans

Non-alcoholic fatty liver (NAFL) is the most common liver disorder in western society. Various factors may play a role in determining hepatic fat content, such as delivery of lipids to the liver, de novo lipogenesis, hepatic lipid oxidation, secretion of intrahepatic lipids to the circulation or a combination of these. If delivery of lipids to the liver outweighs the sum of hepatic lipid oxidation and secretion, the intrahepatic lipid (IHL) content starts to increase and NAFL may develop. NAFL is closely related to obesity and insulin resistance and a fatty liver increases the vulnerability to type 2 diabetes development. Exercise training is a cornerstone in the treatment and prevention of type 2 diabetes. There is a large body of literature describing the beneficial metabolic consequences of exercise training on skeletal muscle metabolism. Recent studies have started to investigate the effects of exercise training on liver metabolism but data is still limited. Here, first, we briefly discuss the routes by which IHL content is modulated. Second, we review whether and how these contributing routes might be modulated by long-term exercise training. Third, we focus on the effects of acute exercise on IHL metabolism, since exercise also might affect hepatic metabolism in the physically active state. This will give insight into whether the effect of exercise training on IHL could be explained by the accumulated effect of acute bouts of exercise, or whether adaptations might occur only after long-term exercise training. The primary focus of this review will be on observations made in humans. Where human data is missing, data obtained from well-accepted animal models will be used.

Increased postprandial apolipoprotein B-48 level after a test meal in diabetic patients: A multicenter, cross-sectional study

OBJECTIVE

To evaluate plasma apolipoprotein B (ApoB)-48 concentrations among Korean diabetic subjects with normal to moderately high levels of low-density-lipoprotein cholesterol (LDL-C).

METHODS

This multicenter, cross-sectional study included subjects with LDL-C levels between 100 and 160mg/dL who had not been treated with a lipid-lowering agent for over 6weeks prior to baseline. Blood tests to assess lipid-profile parameters were conducted in both fasting and postprandial states. This study compared ApoB-48 and other lipid-profile parameters in diabetic and nondiabetic subjects.

RESULTS

Of the 93 subjects enrolled, 88 (42 diabetic; 46 nondiabetic) completed the study. Significantly higher mean incremental area under curve (0-6h; iAUC0-6h) of postprandial ApoB-48 levels was noted among diabetic subjects than nondiabetic subjects (p=0.0078). The mean postprandial ApoB-48 peak level was higher in diabetic subjects; however, the difference was not statistically significant. The fasting ApoB-48 level was similar in both groups: 5.9 (3.5) in diabetics and 7.3 (5.8) in nondiabetics (p=0.18). The iAUC0-6h of postprandial total cholesterol (TC), triglyceride (TG), LDL-C, non-high-density-lipoprotein cholesterol (non-HDL-C), ApoB-100, and remnant cholesterol was similar in both groups. The ApoB-48 level was moderately correlated with TG and non-HDL-C for both groups (p<0.05).

CONCLUSION

Without lipid-lowering treatment, the postprandial increment in ApoB-48 level was significantly higher in Korean diabetic subjects compared with nondiabetic subjects, irrespective of similar LDL-C levels.

Effect of niacin on triglyceride-rich lipoprotein apolipoprotein B-48 kinetics in statin-treated patients with type 2 diabetes

AIM

To investigate the effects of extended-release (ER) niacin on apolipoprotein B-48 (apoB-48) kinetics in statin-treated patients with type 2 diabetes (T2DM).

METHODS

A total of 12 men with T2DM were randomized to rosuvastatin or rosuvastatin plus ER niacin for 12 weeks and then crossed to the alternate therapy. Postprandial metabolic studies were performed at the end of each treatment period. D3-leucine tracer was administered as subjects consumed a high-fat liquid meal. ApoB-48 kinetics were determined using stable isotope tracer kinetics with fractional catabolic rates (FCRs) and secretion rates derived using a non-steady-state compartmental model. Area-under-the-curve (AUC) and incremental AUC (iAUC) for plasma triglyceride and apoB-48 were also calculated over the 10-h period after ingestion of the fat meal.

RESULTS

In statin-treated patients with T2DM, apoB-48 concentration was lower with ER niacin (8.24 ± 1.98 vs 5.48 ± 1.14 mg/l, p = 0.03) compared with statin alone. Postprandial triglyceride and apoB-48 AUC were also significantly lower on ER niacin treatment (-15 and -26%, respectively; p < 0.05), without any change to triglyceride and apoB-48 iAUC. ApoB-48 secretion rate in the basal state (3.21 ± 0.34 vs 2.50 ± 0.31 mg/kg/day; p = 0.04) and number of apoB-48-containing particles secreted in response to the fat load (1.35 ± 0.19 vs 0.84 ± 0.12 mg/kg; p = 0.02) were lower on ER niacin. ApoB-48 FCR was not altered with ER niacin (8.78 ± 1.04 vs 9.17 ± 1.26 pools/day; p = 0.79).

CONCLUSIONS

ER niacin reduces apoB-48 concentration by lowering fasting and postprandial apoB-48 secretion rate. This effect may be beneficial for lowering atherogenic postprandial lipoproteins and may provide cardiovascular disease risk benefit in patients with T2DM.

Pathophysiology of diabetic dyslipidaemia: where are we?

Cardiovascular disease is a major cause of morbidity and mortality in patients with type 2 diabetes mellitus, with a two- to fourfold increase in cardiovascular disease risk compared with non-diabetic individuals. Abnormalities in lipid metabolism that are observed in the context of type 2 diabetes are among the major factors contributing to an increased cardiovascular risk. Diabetic dyslipidaemia includes not only quantitative lipoprotein abnormalities, but also qualitative and kinetic abnormalities that, together, result in a shift towards a more atherogenic lipid profile. The primary quantitative lipoprotein abnormalities are increased triacylglycerol (triglyceride) levels and decreased HDL-cholesterol levels. Qualitative lipoprotein abnormalities include an increase in large, very low-density lipoprotein subfraction 1 (VLDL1) and small, dense LDLs, as well as increased triacylglycerol content of LDL and HDL, glycation of apolipoproteins and increased susceptibility of LDL to oxidation. The main kinetic abnormalities are increased VLDL1 production, decreased VLDL catabolism and increased HDL catabolism. In addition, even though LDL-cholesterol levels are typically normal in patients with type 2 diabetes, LDL particles show reduced turnover, which is potentially atherogenic. Although the pathophysiology of diabetic dyslipidaemia is not fully understood, the insulin resistance and relative insulin deficiency observed in patients with type 2 diabetes are likely to contribute to these lipid changes, as insulin plays an important role in regulating lipid metabolism. In addition, some adipocytokines, such as adiponectin or retinol-binding protein 4, may also contribute to the development of dyslipidaemia in patients with type 2 diabetes.

Postprandial lipemia as a cardiometabolic risk factor

High levels of fasting circulating triglycerides (TG) represent an independent risk factor for cardiovascular disease. In western countries, however, people spend most time in postprandial conditions, with continuous fluctuation of lipemia due to increased levels of TG-rich lipoproteins (TRLs), including chylomicrons (CM), very low density lipoproteins (VLDL), and their remnants. Several factors contribute to postprandial lipid metabolism, including dietary, physiological, pathological and genetic factors. The presence of coronary heart disease, type 2 diabetes, insulin resistance and obesity is associated with higher postprandial TG levels compared with healthy conditions; this association is present also in subjects with normal fasting TG levels. Increasing evidence indicates that impaired metabolism of postprandial lipoproteins contributes to the pathogenesis of coronary artery disease, suggesting that lifestyle modifications as well as pharmacological approaches aimed at reducing postprandial TG levels might help to decrease the cardiovascular risk.

Postprandial changes of lipoprotein profile: effect of abdominal obesity

Background

Majority of studies that focused on the influence of abdominal obesity on lipoprotein profile, were conducted in the fasting conditions. The effects of visceral fat accumulation on postprandial lipoprotein concentrations have not yet been studied in details. We therefore focused on the postprandial lipoprotein profile in otherwise healthy men and women with abdominal obesity and their comparison with the control group of volunteers with normal waist circumference. The concentration of lipoprotein classes and subclasses was measured before and 4 hours after a standard meal by linear polyacrylamide gel electrophoresis.

Results

A statistically significant postprandial rise in triacylglycerol concentration occurred in all subjects. VLDL increased 4 hours after meal in all subjects except the women with normal waist circumference. The concentration of large IDL particles increased in both non-obese men and women. In women with abdominal obesity, however, it decreased, while in obese men there was no statistically significant change. The concentration of small and medium-sized IDL particles decreased in all volunteers. Analyzing subclasses changes of large, medium-sized and small LDL particles we saw no significant shift in their concentrations except the subclass of large LDL particles, which decreased in men. Concentrations of medium and small HDL particles decreased postprandially in all volunteers with normal waist circumference. However, they remained unchanged in subjects with abdominal obesity.

Conclusions

We observed significant postprandial changes of the lipoprotein profile, but the nature and extent of these changes depended on gender and presence of abdominal obesity.

Postprandial hypertriglyceridemia and cardiovascular disease: current and future therapies

Exaggerated postprandial hypertriglyceridemia is a risk factor for cardiovascular disease. This metabolic abnormality is principally due to overproduction and/or decreased catabolism of triglyceride-rich lipoproteins (TRLs) and is a consequence of pathogenic genetic variations and other coexistent medical conditions, particularly obesity and insulin resistance. Accumulation of TRL in the postprandial state promotes the formation of small, dense low-density lipoproteins, as well as oxidative stress, inflammation, and endothelial dysfunction, all of which compound the risk of cardiovascular disease. The cardiovascular benefits of lifestyle modification (weight loss and exercise) and conventional lipid-lowering therapies (statins, fibrates, niacin, ezetimibe, and n-3 fatty acid supplementation) could involve their favorable effects on TRL metabolism. New agents, such as dual peroxisome-proliferator-activated receptor α/δ agonists, diacylglycerol, inhibitors of diacylglycerol acyltransferase 1 and microsomal triglyceride transfer protein, antisense oligonucleotides for apolipoprotein B-100 and apolipoprotein C-III, and incretin-based therapies, may enhance the treatment of postprandial lipemia, but their efficacy needs to be tested in clinical end point trials. Further work is required to develop a simple clinical protocol for investigating postprandial lipemia, as well as internationally agreed management guidelines for this type of dyslipidemia.

An elevated gap between admission and A1C-derived average glucose levels is associated with adverse outcomes in diabetic patients with pyogenic liver abscess

OBJECTIVES

To assess whether chronic glycemic control and stress-induced hyperglycemia, determined by the gap between admission glucose levels and A1C-derived average glucose (ADAG) levels adversely affects outcomes in diabetic patients with pyogenic liver abscess (PLA).

METHODS

Clinical, laboratory, and multi-detector computed tomography (MDCT) findings of 329 PLA patients (2004-2010) were retrospectively reviewed. HbA1C levels were used to determine long-term glycemic control status, which were then converted to estimated average glucose values. For the gap between admission glucose levels and ADAG levels, we used receiver operating characteristic (ROC) curve to determine the optimal cut-off values predicting adverse outcomes. Univariate and multivariate logistic regressions were used to identify predictors of adverse outcomes.

RESULTS

Diabetic PLA patients with poorer glycemic control had significantly higher Klebsiella pneumoniae (KP) infection rates, lower albumin levels, and longer hospital stays than those with suboptimal and good glycemic control. The ROC curve showed that a glycemic gap of 72 mg/dL was the optimal cut-off value for predicting adverse outcomes and showed a 22.3% relative increase in adverse outcomes compared with a glycemic gap<72 mg/dL. Multivariate analysis revealed that an elevated glycemic gap≥72 mg/dL was important predictor of adverse outcomes.

CONCLUSIONS

A glycemic gap≥72 mg/dL, rather than admission hyperglycemia or chronic glycemic control, was significantly correlated with adverse outcomes in diabetic PLA patients. Poorer chronic glycemic control in diabetic PLA patients is associated with high incidence of KP infection, hypoalbuminemia and longer hospital stay.

A comparative study on the fasting and the postprandial dyslipidaemia in type 2 diabetes mellitus

BACKGROUND AND OBJECTIVES

Type 2 Diabetes Mellitus (Type 2 DM), which is characterized by a relative insulin deficiency or insulin resistance is associated with a cluster of metabolic abnormalities, which includes glucose intolerance, hypertension, a unique dyslipidaemia, a procoagulant state, and an increase in macrovascular diseases. The present study was conducted to assess the significance of postprandial dyslipidaemia with respect to fasting dyslipidaemia, in the pathogenesis of atherosclerotic changes and possible cardiovascular diseases (CVD) and complications. Methods and Statistical Analysis: Fifty diagnosed cases of type 2 DM which were in the age group of 35-65 years, which had a duration of diabetes of more than five years, were included in the study and 50 age and sex matched healthy subjects were taken as the controls. In both the study groups, we measured the serum levels of fasting as well as the postprandial lipid profile, which was comprised of the total Cholesterol (TC), triglycerides (TGs), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and the waist-hip ratio (WHI) as the cardiovascular risk factors. The statistical analysis was done by using the Students unpaired 't'-test.

RESULTS

The results of this study showed significantly increased levels of serum total cholesterol, TGs, LDL-C and VLDL-C in the postprandial state as compared to those in the fasting state (p<0.001) and as compared to those in the fasting and the postprandial states of the controls (p<0.001). The serum HDL-C level was significantly lower in the postprandial state as compared to that in the fasting state (p<0.001). Also, the postprandial and the fasting HDL-C levels were significantly lower as compared to the levels in their respective control groups (p<0.001).

CONCLUSION

The findings of the present study indicated that the lipid profile, as a cardiovascular risk factor, was significantly elevated in the postprandial state as compared to that in the fasting state and that it was significantly elevated in the postprandial and the fasting states in the Type 2 DM patients as compared to the levels in their respective control groups. This signified a routine estimation of the postprandial lipid profile, rather than the fasting lipid parameters, in the cardiovascular risk assessment in Type 2 DM.

Favorable impact of Nigella sativa seeds on lipid profile in type 2 diabetic patients

Background and Aim:

The atherogenic pattern of dyslipidemia associated with type 2 diabetes mellitus (DM) has been increasingly discussed. We have recently reported a hypoglycemic effect of Nigella sativa (NS) seeds in patients with type 2 DM. In this study we sought to assess the impact of NS seeds on lipid profile in type 2 diabetic patients.

Patients and Method:

A total of 94 patients with type 2 DM were recruited and divided into 3 dose groups. Capsules containing NS were administered orally in a dose of 1, 2, and 3 g/day for 12 weeks. All patients were subjected to measurement of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c) before treatment and 4, 8, and 12 weeks thereafter.

Results:

Patients receiving 1 g/day NS seeds for 12 weeks (group 1) showed nonsignificant changes in all the parameters except for a significant increase in HDL-c after 4 weeks of treatment. However, patients ingested 2 g/day NS displayed a significant decline in TC, TG, and LDL-c, and a significant elevation in HDL-c/LDL-c, compared with their baseline data and to group 1 patients. Increasing NS dose to 3 g/day failed to show any increase in the hypolipdemic effect produced by the 2 g/day dose.

Conclusion:

NS supplementation at a dose of 2 g/day for 12 weeks may improve the dyslipidemia associated with type 2 diabetic patients. Therefore, NS is a potential protective natural agent against atherosclerosis and cardiovascular complications in these patients.

Postprandial VLDL-triacylglycerol secretion is not suppressed in obese type 2 diabetic men

AIMS/HYPOTHESIS

Type 2 diabetes is characterised by insulin resistance and increased post-absorptive secretion of VLDL-triacylglycerol (VLDL-TAG). Whether postprandial suppression of endogenous VLDL-TAG secretion is abnormal--a finding that would link hyperlipidaemia and type 2 diabetes--remains unclear.

METHODS

Eight type 2 diabetic men and eight healthy men were studied before and after a fat-free test meal (40% of resting energy expenditure). VLDL-TAG kinetics were assessed using a primed-constant infusion of ex vivo labelled [1-(14)C]triolein VLDL-TAG using non-steady-state calculations.

RESULTS

Type 2 diabetic men had a higher basal VLDL-TAG secretion rate and concentration than healthy men (mean ± SD secretion rate 137 ± 61 vs 78 ± 30 μmol/min, respectively [p = 0.03]; median concentration 1.03 [range 0.58-1.75] vs 0.33 [0.13-1.14] mmol/l, respectively [p < 0.01]). Postprandially, the VLDL-TAG secretion rate decreased in healthy men (p < 0.01), but remained unchanged in diabetic men (p = 0.47). The VLDL-TAG concentration increased in diabetic men and decreased in healthy men postprandially (p < 0.05). The difference in VLDL-TAG secretion rate between the two groups approached significance (p = 0.06) and the relative change in VLDL-TAG secretion rate was significantly different (p = 0.01) between the two groups. Basal VLDL-TAG clearance was significantly lower in diabetic men (diabetic men 133 [49-390] ml/min; healthy controls 215 [137-933] ml/min [p < 0.05]). After meal ingestion, clearance decreased in healthy men (p = 0.03), but was unchanged in diabetic men (p = 0.58).

CONCLUSIONS/INTERPRETATION

Obese type 2 diabetic men have impaired postprandial suppression of VLDL-TAG secretion compared with lean healthy men, contributing to their postprandial lipaemia and hypertriacylglycerolaemia.

Postprandial dysmetabolism and the heart

Epidemiologic evidence indicates that abnormal elevations in glycemia and lipidemia after a meal, termed postprandial dysmetabolism, are linked with increased risk of morbidity and mortality due to cardiovascular disease in individuals with or without type 2 diabetes. Both postprandial hyperglycemia and postprandial hyperlipidemia are independently associated with deteriorating endothelial function and vascular damage, which are likely mediated by increased oxidative stress and are more pronounced when both derangements coexist. Pharmacotherapies that target postprandial hyperglycemia and/or postprandial dyslipidemia are likely to improve endothelial function, which may have positive implications for cardiovascular outcomes.

Apolipoprotein A-V modulates multiple atherogenic mechanisms in a mouse model of disturbed clearance of triglyceride-rich lipoproteins

OBJECTIVE

Apolipoprotein A-V plays an important role in reducing plasma triglyceride levels. We hypothesized that expression of apoA-V would inhibit atherogenesis in apoE(-/-) mice fed chow diet which is a known model of hypercholesterolemia. Our aim was to study this protective effect and to explore possible mechanisms.

METHODS AND RESULTS

ApoA-V(+/+)ApoE(-/-) mice expressing human apolipoprotein A-V (hapoA-V) were generated and compared to apoE(-/-) mice. Atherosclerotic aortic sinus lesion area was 70% smaller in hapoA-V(+/+)apoE(-/-). This was accompanied by a 58% reduction in lesion macrophage content. Furthermore, advanced atherosclerotic lesions in hapoA-V(+/+)apoE(-/-) mice showed features of a more stable plaque, manifested by 59% and 37% higher collagen and α-actin content, respectively. Plasma triglyceride and cholesterol levels in hapoA-V(+/+)apoE(-/-) mice were 47% and 33% lower, respectively. These were associated with a 33% reduction in very low density lipoprotein triglyceride production and 2-fold acceleration in triglyceride-rich lipoprotein clearance in hapoA-V(+/+)apoE(-/-) mice. In addition, hapoA-V(+/+)apoE(-/-) mice showed enhanced insulin sensitivity (25% and 15% improvement in glucose tolerance and insulin responsiveness, respectively). Finally, hapoA-V(+/+)apoE(-/-) displayed a milder systemic inflammatory response compared to apoE(-/-) mice, manifested by 22%, 65% and 15% lower plasma levels of TNFα, IL-1β and IL-6, respectively.

CONCLUSIONS

We showed that human apolipoprotein A-V is a potent modulator of atherosclerosis in mice through multiple modes of action. These findings may identify apoA-V as a potential therapeutic target for treatment of atherosclerosis.

Influence of chylomicron remnants on human monocyte activation in vitro

BACKGROUND AND AIMS

Atherosclerosis is known to be an inflammatory disease and there is increasing evidence that chylomicron remnants (CMR), the lipoproteins which carry dietary fats in the blood, cause macrophage foam cell formation and inflammation. In early atherosclerosis the frequency of activated monocytes in the peripheral circulation is increased, and clearance of CMR from blood may be delayed, however, whether CMR contribute directly to monocyte activation and subsequent egress into the arterial wall has not been established. Here, the contribution of CMR to activation of monocyte pro-inflammatory pathways was assessed using an in vitro model.

METHODS AND RESULTS

Primary human monocytes and CMR-like particles (CRLP) were used to measure several endpoints of monocyte activation. Treatment with CRLP caused rapid and prolonged generation of reactive oxygen species by monocytes. The pro-inflammatory chemokines MCP-1 and IL-8 were secreted in nanogram quantities by the cells in the absence of CRLP. IL-8 secretion was transiently increased after CRLP treatment, and CRLP maintained secretion in the presence of pharmacological inhibitors of IL-8 production. In contrast, exposure to CRLP significantly reduced MCP-1 secretion. Chemotaxis towards MCP-1 was increased in monocytes pre-exposed to CRLP and was reversed by addition of exogenous MCP-1.

CONCLUSION

Our findings indicate that CRLP activate human monocytes and augment their migration in vitro by reducing cellular MCP-1 expression. Our data support the current hypothesis that CMR contribute to the inflammatory milieu of the arterial wall in early atherosclerosis, and suggest that this may reflect direct interaction with circulating blood monocytes.

Effects of encapsulated propolis on blood glycemic control, lipid metabolism, and insulin resistance in type 2 diabetes mellitus rats

The present study investigates the encapsulated propolis on blood glycemic control, lipid metabolism, and insulin resistance in type 2 diabetes mellitus (T2DM) rats. The animal characteristics and biological assays of body weight, fasting blood glucose (FBG), fasting serum insulin (FINS), insulin act index (IAI), triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured and euglycemic hyperinsulinemic glucose clamp technique were used to determine these effects. Our findings show that oral administration of encapsulated propolis can significantly inhibit the increasing of FBG and TG in T2DM rats and can improve IAI and M value in euglycemic hyperinsulinemic clamp experiment. There was no significant effects on body weight, TC, HDL-C, and LDL-C in T2DM rats treated with encapsulated propolis. In conclusion, the results indicate that encapsulated propolis can control blood glucose, modulate lipid metabolism, and improve the insulin sensitivity in T2DM rats.

Ezetimibe beneficially influences fasting and postprandial triglyceride-rich lipoproteins in type 2 diabetes

INTRODUCTION

Type 2 diabetes is associated with atherogenic abnormalities of postprandial triglyceride-rich lipoproteins. This study evaluated whether ezetimibe, by inhibiting intestinal cholesterol absorption, influences chylomicrons and VLDL particles at fasting and after a standard meal.

METHODS

By a double blind cross-over design 15 subjects with type 2 diabetes and hypercholesterolaemia followed in random order a 6-week treatment with ezetimibe 10mg+simvastatin 20 mg (EZE+S) or placebo+simvastatin 20 mg (P+S) and, after a 6-week wash-out period, crossed over to the other treatment (NCT00699023). At the end of each period lipids, apoB-48, and apoB-100 concentrations in plasma and lipoprotein fractions (separated by discontinuous density gradient ultracentrifugation) were determined before and over 6h following a high-fat test meal.

RESULTS

Compared with P+S, EZE+S induced, (a) beside a greater decrease in LDL cholesterol, (b) a significant decrease in chylomicron lipid content both at fasting and postprandially (4.4 ± 2.7 vs. 8.3 ± 8.7 mg/dl × 6 h total AUC for cholesterol, p < 0.05; 18 ± 12 vs. 29 ± 24 mg/dl triglyceride concentrations at 6h, p < 0.05), (c) a significant decrease in chylomicron postprandial apoB-48 (0.03 ± 0.03 vs. 0.09 ± 0.08 mg/l at 4 h, p < 0.05), and (d) significant fasting and postprandial decreases in the cholesterol content of VLDL, IDL, and LDL, as shown by the significant reduction of the cholesterol/triglyceride ratio in these lipoproteins.

CONCLUSIONS

A 6-week treatment with ezetimibe and simvastatin, compared to simvastatin alone, positively influences lipoprotein profile both at fasting and postprandially in type 2 diabetic patients by favouring the production of cholesterol-poor chylomicrons and VLDL particles that have less atherogenic potential.

Fructose: a highly lipogenic nutrient implicated in insulin resistance, hepatic steatosis, and the metabolic syndrome

As dietary exposure to fructose has increased over the past 40 years, there is growing concern that high fructose consumption in humans may be in part responsible for the rising incidence of obesity worldwide. Obesity is associated with a host of metabolic challenges, collectively termed the metabolic syndrome. Fructose is a highly lipogenic sugar that has profound metabolic effects in the liver and has been associated with many of the components of the metabolic syndrome (insulin resistance, elevated waist circumference, dyslipidemia, and hypertension). Recent evidence has also uncovered effects of fructose in other tissues, including adipose tissue, the brain, and the gastrointestinal system, that may provide new insight into the metabolic consequences of high-fructose diets. Fructose feeding has now been shown to alter gene expression patterns (such as peroxisome proliferator-activated receptor-γ coactivator-1α/β in the liver), alter satiety factors in the brain, increase inflammation, reactive oxygen species, and portal endotoxin concentrations via Toll-like receptors, and induce leptin resistance. This review highlights recent findings in fructose feeding studies in both human and animal models with a focus on the molecular and biochemical mechanisms that underlie the development of insulin resistance, hepatic steatosis, and the metabolic syndrome.

Hepatic FoxO1 ablation exacerbates lipid abnormalities during hyperglycemia

Patients with diabetes suffer disproportionately from impaired lipid metabolism and cardiovascular disease, but the relevant roles of insulin resistance and hyperglycemia in these processes are unclear. Transcription factor FoxO1 is regulated dually by insulin and nutrients. In this study, we addressed the hypothesis that, in addition to its established role to regulate hepatic glucose production, FoxO1 controls aspects of lipid metabolism in the diabetic liver. Mice with a liver-specific deletion of FoxO1 (L-FoxO1) and their control littermates were rendered hyperglycemic by streptozotocin administration. Subsequently, we monitored serum lipids, liver VLDL secretion, and hepatic expression of genes related to lipid metabolism. Hepatic FoxO1 ablation resulted in increased VLDL secretion, increased cholesterol, and increased plasma free fatty acids, three hallmarks of the diabetic state. l-FoxO1 mice expressed increased levels of SREBP-2 and FGF21 without affecting lipogenic genes. We propose that FoxO1 fine tunes lipolysis through its actions on FGF21 and that hepatic FoxO1 ablation increases availability of substrates for hepatic triglyceride and cholesterol synthesis and VLDL secretion. The implications of these findings are that FoxO1 protects against excessive hepatic lipid production during hyperglycemia and that its inhibition by intensive insulin treatment may exacerbate paradoxically the lipid abnormalities of diabetes.

Type 2 diabetes mellitus is characterized by reduced postprandial adiponectin response: a possible link with diabetic postprandial dyslipidemia

We investigated postprandial plasma and adipose tissue (AT) adiponectin changes in relation to obesity and type 2 diabetes mellitus. Fasting and 6 hours after a standard fat-rich meal blood samples (adiponectin, glucose, insulin, lipids) and needle biopsies of abdominal subcutaneous AT (adiponectin messenger RNA, lipoprotein lipase activity) were taken in 10 obese diabetic (OD), 11 obese nondiabetic (OND), and 11 normal-weight control (C) men. The OD and OND subjects had similar adiposity (body mass index, waist circumference) and insulin resistance (hyperinsulinemic euglycemic clamp). Fasting plasma adiponectin and AT gene expression were not significantly different between groups. After meal, plasma adiponectin decreased in OD but significantly increased in OND and C, the changes being significantly different between groups (analysis of variance, P = .01); adiponectin messenger RNA decreased in OD (-0.27 +/- 0.25 AU, P = .01) but was unchanged in OND (P = .59) and C (P = .45). After meal, plasma adiponectin correlated inversely with triglyceride and cholesterol concentrations in chylomicrons and large very low-density lipoprotein, and directly with AT lipoprotein lipase activity (P < .05 for all). Type 2 diabetes mellitus is associated with lower postprandial plasma levels and AT gene expression of adiponectin independently of degree of adiposity and whole-body insulin sensitivity. In patients with diabetes, this may exacerbate postprandial abnormalities of lipoprotein metabolism.

Differential lipid profile and hormonal response in type 2 diabetes by exogenous insulin aspart versus the insulin secretagogue repaglinide, at the same glycemic control

Our aim was to study, at the same glycemic control, how treatment with either the insulin secretagogue repaglinide or exogenous insulin aspart affects endogenous insulin secretion, plasma insulin and IAPP (islet amyloid polypeptide) levels, GH-IGF (growth hormone-insulin-like growth factor) axis and plasma lipoprotein concentrations in patients with type 2 diabetes. Five patients, age 65.0+/-4.1 years (mean+/-SE), body weight 82.5+/-5.0 kg, BMI (body mass index) 27.7+/-1.5 kg/m(2) were treated for 10 weeks with repaglinide or insulin aspart in a randomized, cross-over study. At the end of each treatment a 24-h metabolic profile was performed. Blood glucose, C-peptide, free human insulin, free total (human and analogue) insulin, proinsulin, IAPP, IGF-I, IGFBP-1 (IGF binding protein-1), GHBP (growth hormone binding protein) and plasma lipoprotein concentrations were measured. Similar 24-h blood glucose profiles were obtained with repaglinide and insulin aspart treatment. During the repaglinide treatment, the meal related peaks of C-peptide and free human insulin were about twofold higher than during treatment with insulin aspart. Proinsulin, GHBP were higher and IAPP levels tended to be higher during repaglinide compared to insulin aspart. Postprandial plasma total cholesterol, triglycerides and apolipoprotein B concentrations were higher on repaglinide than on insulin aspart treatment. Our results show that, at the same glycemic control, treatment with exogenous insulin aspart in comparison with the insulin secretagogue repaglinide result in a lower endogenous insulin secretion, and a tendency towards a less atherogenic postprandial lipid profile.

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

BACKGROUND AND AIMS

Postprandial 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 RESULTS

Ten 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 (6h) 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.6h) than C (87+/-13 mg/dl.6h, M+/-SEM, p<0.05). OD had an increased chylomicron response compared to O (triglyceride incremental AUC 132+/-23 vs. 75+/-14 mg/dl.6h, p<0.05). OD had significantly lower fasting and postprandial adipose tissue heparin-releasable LPL activity than O and C.

CONCLUSIONS

In 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.

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.

Impaired endothelial function in adolescents with type 1 diabetes mellitus

OBJECTIVE

To evaluate the effect of a high-fat meal on endothelial function in adolescents with type 1 diabetes mellitus (T1D).

STUDY DESIGN

Twenty-three children with T1D, aged 12 to 18 years, and age- and sex-matched healthy control subjects were assessed for baseline macronutrient intake, and endothelial function was measured both fasting and after a standardized fast-food, high-fat breakfast.

RESULTS

Endothelial function, assessed noninvasively by peripheral arterial tonometry, was impaired in the T1D group in the fasting state as compared with control subjects (T1D 1.78 +/- 0.4, control subjects 2.06 +/- 0.4, P = .02), and worsened postprandially in both groups (T1D 1.45 +/- 0.3, control subjects 1.71 +/- 0.3, P = .01). Both groups demonstrated significantly elevated triglyceride levels 3.5 hours after ingestion of the high-fat meal (T1D 114.8 +/- 42.8 and control subjects 126.7 +/- 54.9 mg/dL). Nutrient intake in both groups showed higher than recommended intakes of total fat, saturated fat, and cholesterol.

CONCLUSIONS

Patients with T1D exhibited worse endothelial function both before and after a high-fat breakfast than their peers. This suggests that patients with T1D are at greater risk of vascular impairment after a high-fat meal, the cumulative effect of which may contribute to the higher atherosclerotic burden observed in T1D.

Effects of monounsaturated vs. saturated fat on postprandial lipemia and adipose tissue lipases in type 2 diabetes

BACKGROUND

The effects of different dietary fatty acids on postprandial lipid metabolism in type 2 diabetic patients are still debated.

AIM

To evaluate the effects of monounsaturated (MUFA) vs. saturated fat (SAFA)-rich diets on postprandial lipemia and adipose tissue lipoprotein lipase (LPL), and hormone-sensitive lipase (HSL) in type 2 diabetes.

MATERIALS AND METHODS

Eleven type 2 diabetic patients followed, in random order, a diet rich in MUFA (SAFA 8%, MUFA 23%) and another rich in SAFA (SAFA 17%, MUFA 15%) for a period of 3 weeks each. At the end of the two diets, a standard fat-rich meal was administered and subcutaneous fat biopsies were performed at fasting and 6h after the test meal.

RESULTS

Neither diet induced significant changes in meal lipid tolerance, except for a faster (at 2h) increase in chylomicron triglycerides and a significant decrease in small VLDL triglyceride incremental area after the MUFA diet (-13.6+/-4.7 mg/dl*6h vs. -2.2+/-3.7 mg/dl*6h, p<0.005) (M+/-SEM). LPL and HSL activities were significantly increased after the MUFA diet.

CONCLUSIONS

A MUFA-rich diet reduces postprandial small VLDL triglycerides in type 2 diabetic patients compared to a SAFA-rich diet, and modifies lipolytic enzymes in adipose tissue.

Improvement of postprandial lipid handling and glucose tolerance in a non-diabetic population by the dual PPARalpha/gamma agonist, tesaglitazar

This study examined the effect of tesaglitazar (GALIDA), a dual peroxisome proliferator-activated receptor (PPAR)alpha/gamma agonist, on postprandial metabolism. This investigation was part of the Study in Insulin Resistance (SIR) (SH-SBT-0001), a randomised, double-blind, placebo-controlled study that reported improvements in fasting lipid and glucose values with tesaglitazar (0.1, 0.25, 0.5 or 1 mg once daily for 12 weeks) in hypertriglyceridaemic, abdominally obese, non-diabetic patients. A subgroup of 222 patients underwent postprandial lipid and glucose testing at baseline and treatment end. Tesaglitazar 0.25, 0.5 and 1 mg reduced postprandial area under the curve (AUC) for triglycerides by 20% (p=0.003), 30% (p<0.0001) and 41% (p<0.0001), respectively. Free fatty acid (FFA) levels were reduced by 17% with tesaglitazar 0.5 mg (p=0.002) and by 29% with tesaglitazar 1 mg (p<0.0001). Tesaglitazar significantly improved glucose tolerance and increased the proportion of patients with normal glucose tolerance as measured by the oral glucose tolerance test (OGTT). To conclude, postprandial dyslipidaemia and hyperglycaemia, indicators of increased vascular risk, were significantly improved by tesaglitazar treatment in these non-diabetic, hypertriglyceridaemic, abdominally obese subjects.

Short-term administration of orlistat reduced daytime triglyceridemia in obese women with the metabolic syndrome

The objective of this prospective, controlled, randomized study was to evaluate the effect of orlistat administration for 10 days on daytime capillary triglyceridemia in obese women with metabolic syndrome (MetSyn). Thirty-two obese, nondiabetic women with MetSyn were evaluated. The presence of MetSyn was defined according to the National Cholesterol Education Program (NCEP)-Adult Treatment Panel III (ATP III) criteria. Patients were randomized into 2 similar groups: group A (orlistat), mean age 50.1 -/+ 8.2 years, received a low-calorie diet combined with orlistat 120 mg tid for 10 days and group B (control), mean age 51.2 -/+ 9.1 years, received only the low-calorie diet for the same period of time. Anthropometric, lipids, and parameters of insulin resistance were measured before and after 10 days of intervention. Capillary triglycerides (TGc) were measured at 6 different time points during the day and daytime triglyceridemia was expressed as area under the curve of TGc (AUC-TGc). Most anthropometric measurements (body weight, body mass index, waist circumference, and percentage of fat mass) and most metabolic parameters (total cholesterol [TC], fasting venous triglycerides [TGfv], high-density lipoprotein cholesterol [HDL-C] levels, fasting glucose [FG], fasting insulin [FI], and homeostasis model for assessment [HOMA] for insulin resistance index) decreased significantly in both groups, while waist-to-hip ratio (WHR) and systolic (SBP) and diastolic blood pressure (DBP) did not change significantly in both groups and low-density lipoprotein cholesterol (LDL-C) levels decreased only in the orlistat group. Following minimal weight loss, TGc at most time points and AUC-TGc were significantly reduced only in group A. In group A, AUG-TGc decreased by 17% from 36.4 -/+11.8 to 30.2 -/+9.9 mmol/Lxh(-1) (p < 0.001), and this reduction was significantly greater compared with the control group (p < 0.05) and remained significant after percentage of weight loss was taken into account. This decrease of AUC-TGc significantly correlated with the decrease of HOMA index (p < 0.05, r = 0.39) and the decrease of TGfv (p < 0.001, r = 0.62). The tolerability of orlistat was very good and side effects were transient and of minimal intensity. In conclusion, short-term administration of orlistat significantly reduced daytime triglyceridemia in obese, nondiabetic women with MetSyn. This reduction could offer cardiovascular benefits in these high-risk patients. Long-term studies with more patients are needed to reach definite conclusions.

Postprandial effect of n-3 polyunsaturated fatty acids on apolipoprotein B-containing lipoproteins and vascular reactivity in type 2 diabetes

BACKGROUND

Plasma lipoproteins may be classified by their apolipoprotein composition. The lipoprotein subclass containing apolipoproteins B and C (LpB:C) is considered the most atherogenic.

OBJECTIVE

We evaluated the acute effects of individual fatty acids on apolipoprotein B (apo B)-containing lipoproteins in adults with type 2 diabetes (n = 15).

DESIGN

We administered 3 meals in a randomized, double-blind, crossover design. Treatments contained skim milk and 50 g fat from high-oleic acid safflower and canola oils (monounsaturated fatty acid; MUFA), MUFA + 3.5 g alpha-linolenic acid (ALA; MUFA + ALA) from high-ALA canola oil, or MUFA + 4.0 g both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA; MUFA + EPA/DHA) from sardine oil. Apo B, LpB, LpB:C, LpB:E + LpB:C:E, and LpA-II:B:C:D:E were measured at baseline and 2 and 4 h after the meal. Flow-mediated dilation was measured at baseline and 4 h after the meal.

RESULTS

The treatments significantly increased apo B and LpB postprandially (P < 0.03 for both), but the magnitude of the changes did not differ significantly between the treatments. The postprandial change in LpB:C was 23% lower after MUFA + EPA/DHA than after MUFA (treatment x time interaction, P < 0.0001). MUFA + ALA attenuated the increase in LpA-II:B:C:D:E in those with high triacylglycerols (>/=1.69 mmol/L) but was the only treatment to significantly increase this particle in those with low triacylglycerols (treatment x group interaction, P < 0.0001). Examination of change scores did not reveal the source of the interaction of treatment and time (P < 0.007) for LpB:E + LpB:C:E. Furthermore, the subjects with the largest increases in LpB:C exhibited the largest impairment in endothelial function.

CONCLUSIONS

The results suggest that unsaturated fatty acids differentially affect concentrations of apo B-containing lipoprotein subclasses. A rise in LpB:C adversely affects endothelial function. Meals containing MUFA + EPA/DHA attenuated the postprandial rise in LpB:C and the impairment of endothelial function.

Regulation of postprandial lipemia: an update on current trends

People spend a large percentage of their waking hours in the postprandial state. Postprandial lipemia is associated with disruptions in lipoprotein metabolism and inflammatory factors, cardiovascular disease, MetS, and diabetes. Commonly, the dietary sources of fat exceed the actual needs and the tissues are faced with the excess, with accumulation of chylomicrons and remnant particles. This review will summarize recent findings in postprandial lipemia research with a focus on human studies. The effects of dietary factors and other meal components on postprandial lipemia leads to the following question: do we need a standardized oral lipid tolerance test (OLTT)? An overview of recent findings on FABP2, MTP, LPL, apoAV, and ASP and the effects of body habitus (sex influence and body size), as well as exercise and weight loss, on postprandial lipemia will be summarized.