Pathogenesis of dyslipidemia in type 2 diabetes

Dyslipidemia among Patients with Type 2 Diabetes Mellitus Visiting a Tertiary Care Centre

Introduction

A triad of lipid and lipoprotein metabolism is known as dyslipidemia. Dyslipidemia is one of the major risk factors for cardiovascular diseases in diabetes mellitus which is a leading cause of morbidity and mortality worldwide. The aim of the study was to find out the prevalence of dyslipidemia among patients with type 2 diabetes mellitus visiting a tertiary care centre.

Methods

A descriptive cross-sectional study was conducted in a tertiary care centre among patients with type 2 diabetes mellitus from 18 February 2020 to 18 August 2020 after obtaining ethical clearance from the Institutional Review Committee. Demographic and blood samples were analysed and recorded using validated and calibrated tools. A convenience sampling technique was used. The point estimate was calculated at a 95% Confidence Interval.

Results

Out of 390 patients with type 2 diabetes mellitus, 343 (87.95%) (84.72-91.18, 95% Confidence Interval) had dyslipidemia. The most prevalent dyslipidemia was high low-density lipoprotein cholesterol at 85 (24.78%) followed by mixed dyslipidemia at 305 (88.92%).

Conclusions

The prevalence of dyslipidemia among patients with type 2 diabetes mellitus was found to be higher than studies conducted in similar settings. We recommend regular testing of blood glucose and blood lipid levels for early detection of dyslipidemia and putting them under medical supervision to reduce the unwanted complications of cardiovascular diseases.

Keywords

cardiovascular disease; dyslipidemia; prevalence; type 2 diabetes mellitus.

The pattern of dyslipidaemia and factors associated with elevated levels of non-HDL-cholesterol among patients with type 2 diabetes mellitus in the Ho municipality: A cross sectional study

Background

Dyslipidaemia is a key comorbid condition of type 2 diabetes mellitus that increases the risk of cardiovascular disease. This study describes the pattern of dyslipidaemia and factors associated with elevated levels of non-high density lipoprotein cholesterol (HDL-C) among patients with type 2 diabetes mellitus in Ho.

Methods

This hospital-based cross-sectional study enrolled 210 patients with type 2 diabetes mellitus from Ho municipality. A semi-structured questionnaire was used to obtain demographic and other relevant parameters. Anthropometric, haemodynamic, and biochemical variables were obtained using standard methods. Dyslipidaemia was defined according to the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) criteria while elevated levels of non-HDL-C was defined as non-HDL-C level ≥3.37 mmol/L. A Chi-square test and multivariate logistic regression analyses were performed to determine factors associated with elevated non-HDL-C levels.

Results

Overall, dyslipidaemia and elevated levels of non-HDL-C prevalence was 67.1% and 64.3%, respectively. The frequency of atherogenic, isolated, and mixed dyslipidaemias were 10.5%, 58.09% and 53.33 %, respectively. Females were four times more likely to develop elevated levels of non-HDL-C after adjustment for age (AOR: 4.07; CI: 2.20-7.51; p < 0.0001). Likewise, overweight (AOR: 3.1; CI: 1.45-6.61; p = 0.0035), grade 1 obesity (AOR: 2.8; CI: 1.20-6.49; p = 0.0168), and truncal obesity (AOR: 3.09; CI: 1.54-6.19; p < 0.0001) were three times each more likely to develop elevated levels of non HDL-C after adjustment for age and gender. However, alcohol intake was 66% unlikely to develop elevated levels of non-HDL-C (COR: 0.34; CI: 0.16-0.73; p = 0.006).

Conclusion

Dyslipidaemia and elevated levels of non-HDL-C were common in our study participants. Hypercholesterolaemia and co-occurrence of high TG and high LDL-C levels were the most prevalent isolated and mixed dyslipidaemias, respectively. The female gender, overweight, grade 1 obesity and truncal obesity, as well as alcohol intake were significant predictors of elevated levels of non-HDL-C.

Comparing dietary score associations with lipoprotein particle subclass profiles: A cross-sectional analysis of a middle-to older-aged population

BACKGROUND AND OBJECTIVES

Lipoprotein particle concentrations and size are associated with increased risk for atherosclerosis and premature cardiovascular disease. Studies also suggest that certain dietary behaviours may be cardioprotective. Limited comparative data regarding any dietary score/index-lipoprotein particle subclass associations exist. Thus, our objective was to assess relationships between the Dietary Approaches to Stop Hypertension (DASH), Health Eating Index-2015 (HEI-2015), Mediterranean Diet (MD) and Energy-adjusted Dietary Inflammatory Index (E-DII™) scores and plasma lipids and lipoprotein profiles to test the hypothesis that healthier diet (better quality and more anti-inflammatory) would be associated with a more favourable lipoprotein profile.

MATERIALS AND METHODS

This was a cross-sectional study of 1862 men and women aged 46-73 years, randomly selected from a large primary care centre in Ireland. DASH, HEI-2015, MD and E-DII scores were derived from food frequency questionnaires. Lipoprotein subclass particle concentrations and size were determined using nuclear magnetic resonance spectroscopy. Correlation and multivariate-adjusted linear regression analyses with correction for multiple testing were performed to examine dietary score relationships with lipoprotein particle subclasses.

RESULTS

In fully adjusted models, higher diet quality or a more anti-inflammatory diet was associated with less large and medium very low-density lipoprotein (VLDL) (DASH and HEI-2015), intermediate-density lipoprotein (IDL) (DASH, MD and E-DII) and small high-density lipoprotein (HDL) (DASH, HEI-2015 and E-DII) particles. After accounting for multiple testing, relationships with large VLDL (DASH: β = -0.102, p = .037), IDL (DASH: β = -0.089, p = .037) and small HDL (DASH: β = -0.551, p = .014 and E-DII: β = 0.483, p = .019) concentrations persisted.

CONCLUSIONS

These findings provide evidence that better diet quality, determined by the DASH score, may be more closely associated with a more favourable lipoprotein particle subclass profile in middle-to older-aged adults than the HEI-2015, MD and E-DII scores. A less pro-atherogenic lipoprotein status may be a potential mechanism underlying the cardioprotective effects of higher dietary quality.

Hepatic VLDL secretion: DGAT1 determines particle size but not particle number, which can be supported entirely by DGAT2

We investigated whether, in view of its activity being expressed on both aspects of the endoplasmic reticulum (ER; dual membrane topology), diacylglycerol acyltransferase 1 (DGAT1) plays a distinctive role in determining the triglyceride (TAG) content of VLDL particles secreted by the liver. Mice in which the DGAT1 gene was specifically ablated in hepatocytes (DGAT1-LKO mice) had the same number of VLDL particles (apoB concentration) in the plasma 1 h after Triton 1339 treatment, but these particles were approximately half the size of VLDL particles secreted by control mice and had a proportionately decreased content of TAG, with normal cholesterol and cholesteryl ester contents. Analyses of purified microsomal fractions prepared from 16 h fasted control and DAGT1-LKO mice showed that the TAG/protein ratio in the ER was significantly lower in the latter. Electron micrographs of these livers showed that those from DGAT1-LKO mice did not show the increased lipid content of the smooth ER shown by control livers. The effects of DGAT1- and DGAT2-specific inhibitors on apoB secretion by HepG2 cells showed that DGAT1 is not indispensable for apoB secretion and demonstrated redundancy in the ability of the two enzymes to support apoB secretion. Therefore, our findings show that DGAT1 is essential for the complete lipidation and maturation of VLDL particles within the lumen of the ER, consistent with its dual topology within the ER membrane. In the mouse, DGAT2 can support apoB secretion (particle number) even when TAG availability for full VLDL lipidation is restricted in the absence of DGAT1.

Relationship between dietary quality, determined by DASH score, and cardiometabolic health biomarkers: A cross-sectional analysis in adults

BACKGROUND AND AIMS

The relationship between dietary patterns and cardiometabolic disease is of increasing interest. However, limited data regarding the association between dietary quality and biomarkers of cardiometabolic health exist. Therefore the aim of this work was to examine potential associations between dietary quality, assessed using the Dietary Approaches to Stop Hypertension (DASH) dietary quality score, adiposity and biomarkers of glucose homeostasis, lipoprotein metabolism and inflammation in a cross-sectional sample of 1493 men and women.

METHODS

Anthropometric measurements included BMI, hip and waist circumference (WC). Serum acute-phase reactants, adipocytokines, pro-inflammatory cytokines and white blood cell (WBC) counts were determined. Lipoprotein particle size and subclass concentrations were measured using nuclear magnetic resonance (NMR) spectroscopy. Insulin resistance was calculated by homeostasis model assessment (HOMA-IR).

RESULTS

Higher dietary quality was associated with lower BMI (P < 0.05), WC (P < 0.001), tumour necrosis factor α (TNF-α), interleukin 6 (IL-6), WBC and plasminogen activator inhibitor-1 (PAI-1) concentrations (P < 0.01) and reduced insulin resistance (P < 0.05). In addition less small low density lipoprotein (LDL) and small high density lipoprotein (HDL) particles and less large very low density lipoprotein (VLDL) particles were observed among those with better dietary quality (P < 0.001). Individuals in the top DASH quartile had a 54% and 48% lower likelihood of central obesity and metabolic syndrome (MetS), respectively, than those in the lowest DASH quartile (P < 0.05).

CONCLUSIONS

Our data suggest that higher quality diet is associated with improved adiposity measures and a less insulin resistant, pro-inflammatory, pro-thrombotic and pro-atherogenic cardiometabolic profile which may impact on central obesity and MetS risk. These findings, which may be of clinical and public health significance in terms of dietary approaches to promote cardiometabolic health, warrant further examination.

Replacement of Sedentary Time with Physical Activity: Effect on Lipoproteins

PURPOSE

Limited data on the relationship between physical activity and lipoprotein particle profiles exist. Our objective was to investigate associations between objectively measured physical activity and lipoprotein particle size and number, and specifically whether substituting daily sedentary behavior with light activity or moderate-to-vigorous physical activity (MVPA) is associated with beneficial alterations to the lipoprotein profile among adults and those at increased cardiometabolic risk (obese and insulin-resistant subjects).

METHODS

Sedentary behavior and physical activity intensity and duration were measured for 7 consecutive days using the GENEActiv accelerometer in a cross-sectional adult cohort (n = 396; mean age, 59.6 ± 5.5 yr). Lipoprotein particle size and subclass concentrations were determined using nuclear magnetic resonance spectroscopy. Isotemporal substitution regression modeling quantified the associations between replacing 30 min·d of sedentary behavior with equal amounts of light activity and MVPA on lipoprotein profiles.

RESULTS

Daily duration of MVPA was inversely associated with large VLDL particles and lipoprotein insulin resistance scores (P < 0.05, after adjustment for sedentary time and other confounding factors). Reallocating 30 min of sedentary time with MVPA, but not light activity, was associated with less large VLDL particles resulting in more favorable average VLDL particle size and improved lipoprotein insulin resistance score (P < 0.05). Analysis of high-cardiometabolic-risk groups revealed similar beneficial alterations to VLDL profiles (P < 0.05) with substitution of sedentary time for MVPA among the insulin-resistant (homeostasis model assessment for insulin resistance ≥75th percentile) but not the obese (body mass index ≥30 kg·m) individuals.

CONCLUSIONS

Daily MVPA duration and theoretical replacement of sedentary time with MVPA, but not light activity, were associated with less atherogenic VLDL profiles, particularly among the insulin-resistant individuals. These findings, which require further investigation, highlight the need to develop physical activity interventions aimed at improving atherogenic dyslipidemia and lowering cardiometabolic risk.

Pharmacologic Treatment of Dyslipidemia in Diabetes: A Case for Therapies in Addition to Statins

PURPOSE OF REVIEW

The purpose of the study is to review the use of statins and the role of both non-statin lipid-lowering agents and diabetes-specific medications in the treatment of diabetic dyslipidemia.

RECENT FINDINGS

Statins have a primary role in the treatment of dyslipidemia in people with type 2 diabetes, defined as triglyceride levels >200 mg/dl and HDL cholesterol levels <40 mg/dL. A number of clinical trials suggest that treatment with a fibrate may reduce cardiovascular events. However, the results of these trials are inconsistent, probably because many of their participants did not have dyslipidemia. The choice of medications used to treat diabetes can have major implications regarding management of dyslipidemia; metformin, GLP-1 agonists, and pioglitazone all have favorable lipid effects. These agents, as well as the new SGLT2 inhibitors, may reduce cardiovascular events. Management of dyslipidemia in people with type 2 diabetes should start with statin therapy and optimal glycemic control with agents that have favorable lipid and cardiovascular effects. We believe that there is a role for adding fenofibrate to moderate-intensity statins in selected patients with true dyslipidemia. We propose an algorithm for selecting add-on medications for diabetes (after metformin) based on lipid status.

Prevalence and pattern of dyslipidemia in Nepalese individuals with type 2 diabetes

Background

Atherogenic dyslipidemia is an important modifiable risk factor for cardiovascular disease among patients of type 2 diabetes mellitus. Timely detection and characterization of this condition help clinicians estimate future risk of cardiovascular disease and take appropriate preventive measures. The aim of this study was to determine the prevalence, pattern and predictors of dyslipidemia in a cohort of Nepalese patients with type 2 diabetes.

Results

We found mixed dyslipidemia as the most prevalent (88.1%) and isolated dyslipidemia (10.1%) as the least prevalent forms of dyslipidemia in our patients. The most prevalent form of single dyslipidemia was high LDL-C (73.8%) and combined dyslipidemia was high TG, high LDL-C and low HDL-C (44.7%). Prevalence of all single and mixed dyslipidemia was higher in patients with poor glycemic control and hypertension. The glycemic status of patients correlated with their fasting serum lipid profile. Dyslipidemia was associated mainly with male gender, poor glycemic control and hypertension.

Conclusions

Atherogenic dyslipidemia is associated mainly with male gender, poor glycemic control and hypertension. It is highly prevalent in Nepalese patients with type 2 diabetes. Urgent lifestyle modification, sustained glycemic control and aggressive lipid lowering treatment plans are necessary to minimize the future risk of cardiovascular disease in this population.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-017-2465-4) contains supplementary material, which is available to authorized users.

Vitamin C may have similar beneficial effects to Gemfibrozil on serum high-density lipoprotein-cholesterol in type 2 diabetic patients

Objective:

Type 2 diabetes mellitus (DM-T2) is commonly associated with increased triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and low high-density lipoprotein cholesterol (HDL-C) levels. Fibrates like gemfibrozil are frequently used in diabetic patients to decrease TG and increase HDL-C levels. We compared the efficacy of Vitamin C, an antioxidant vitamin, with gemfibrozil on serum HDL-C in diabetic patients.

Methods:

Type 2 diabetic patients, referred to our out-patient clinic were randomly divided into three groups. After 1 month of lifestyle and diet modifications, groups A, B, and C were prescribed 1000 mg Vitamin C, 600 mg gemfibrozil and combination of both, respectively. Before the study initiation and after 6^th week of drug prescription, the blood samples were taken and analyzed for total cholesterol (Total-C), HDL-C, TG, fasting blood sugar (FBS), and hemoglobin A1c (HbA1c) levels.

Findings:

Sixty-seven patients entered, and 50 patients (18 male, 32 female) finished the study. Overall, serum HDL-C increased significantly from 39.8 to 45.2 mg/dL in the participants (P = 0.001). HDL-C increased 6.3, 4.4 and 5.0 mg/dL in groups A, B and C, respectively (related significances were 0.017, 0.022 and 0.033, respectively). Significant decrease of serum TG and Total-C occurred in gemfibrozil and combination groups, but not in Vitamin C group. Changes in serum HDL-C between three groups were not significant (P = 0.963). We found a significant decrease in TG and Total-C in the groups B and C (P < 0.05), but no significant changes of TG, Total-C, LDL-C, FBS and HbA1c in group A (P > 0.05).

Conclusion:

The results demonstrated that Vitamin C may have beneficial effects on HDL-C in diabetic patients without significant effects on plasma glucose or other lipid parameters; however, its role for the treatment of low HDL-C patients should be evaluated in larger studies.

Metabolic effects of fluvastatin extended release 80 mg and atorvastatin 20 mg in patients with type 2 diabetes mellitus and low serum high-density lipoprotein cholesterol levels: a 4-month, prospective, open-label, randomized, blinded-end point (probe) trial

BACKGROUND

Diabetic dyslipidemia is characterized by greater triglyceridation of all lipoproteins and low levels of plasma high-density lipoprotein cholesterol (HDL-C). In this condition, the serum level of low-density lipoprotein cholesterol (LDL-C) is only slightly elevated. The central role of decreased serum HDL-C level in diabetic cardiovascular disease has prompted the establishment of a target of ≥50 mg/dL in patients with diabetes mellitus (DM).

OBJECTIVE

The aim of the study was to assess the effects of once-daily administration of fluvastatin extended release (XL) 80 mg or atorvastatin 20 mg on serum HDL-C levels in patients with type 2 DM and low levels of serum HDL-C.

METHODS

This 4-month, prospective, open-label, randomized, blinded-end point (PROBE) trial was conducted at Endocrinology and Diabetology Service, L. Sacco-Polo University Hospital (Milan, Italy). Patients aged 45 to 71 years with type 2 DM receiving standard oral antidiabetic therapy, with serum HDL-C levels <50 mg/dL, and with moderately high serum levels of LDL-C and triglycerides (TG) were enrolled. After 1 month of lifestyle modification and dietary intervention, patients who were still showing a decreased HDL-C level were randomized, using a 1:1 ratio, to receive fluvastatin XL 80-mg tablets or atorvastatin 20-mg tablets, for 3 months. Lipoprotein metabolism was assessed by measuring serum levels of LDL-C, HDL-C, TG, apolipoprotein (apo) A-I (the lipoprotein that carries HDL), and apo B (the lipoprotein that binds very low-density lipoprotein cholesterol, intermediate-density lipoprotein, and LDL on a molar basis). Patients were assessed every 2 weeks for treatment compliance and subjective adverse events. Serum creatine phosphokinase and liver enzymes were assessed before the run-in period, at the start of the trial, and at 1 and 3 months during the study.

RESULTS

One hundred patients were enrolled (50 patients per treatment group; fluvastatin XL group: 33 men, 17 women; mean [SD] age, 58 [12] years; atorvastatin group: 39 men, 11 women; mean [SD] age, 59 [11] years). In the fluvastatin group after 3 months of treatment, mean (SD) LDL-C decreased from 149 (33) to 95 (25) mg/dL (36%; P < 0.01), TG decreased from 437 (287) to 261 (164) mg/dL (40%; P < 0.01), and HDL-C increased from 41 (7) to 46 (10) mg/dL (12%; P < 0.05). In addition, apo A-I increased from 118 (18) to 124 (15) mg/dL (5%; P < 0.05) and apo B decreased from 139 (27) to 97 (19) mg/dL (30%; P < 0.05). In the atorvastatin group, LDL-C decreased from 141 (25) to 84 (23) mg/dL (40%; P < 0.01) and TG decreased from 411 (271) to 221 (87) mg/dL (46%; P < 0.01). Neither HDL-C (41 [7] vs 40 [6] mg/dL; 2%) nor apo A-I (117 [19] vs 114 [19] mg/dL; 3%) changed significantly. However, apo B decreased significantly, from 131 (20) to 92 (17) mg/dL (30%; P < 0.05). Mean changes in HDL-C (+5 [8] vs -1 [2] mg/dL; P < 0.01) and apo A-I (+6 [18] mg/dL vs -3 [21] mg/dL; P < 0.01) were significantly greater in the fluvastatin group than in the atorvastatin group, respectively. However, the decreases in LDL-C (54 [31] vs 57 [32] mg/ dL), TG (177 [219] vs 190 [65] mg/dL), and apo B (42 [26] vs 39 [14] mg/dL) were not significantly different between the fluvastatin and atorvastatin groups, respectively. No severe adverse events were reported.

CONCLUSIONS

Fluvastatin XL 80 mg and atorvastatin 20 mg achieved mean serum LDL-C (≤ 100 mg/dL) and apo B target levels (≤ 100 mg/dL) in the majority of this population of patients with type 2 DM, but mean serum HDL-C level was increased significantly only with fluvastatin-16 patients (32%) in the fluvastatin group compared with none in the atorvastatin group achieved HDL-C levels ≥50 mg/dL. The increase in HDL-C in the fluvastatin-treated patients was associated with an increase in apo A-I, suggesting a potential pleiotropic and selective effect in patients with low HDL-C levels.

Hepatic triacylglycerol synthesis and secretion: DGAT2 as the link between glycaemia and triglyceridaemia

lThe liver regulates both glycaemia and triglyceridaemia. Hyperglycaemia and hypertriglyceridaemia are both characteristic of (pre)diabetes. Recent observations on the specialised role of DGAT2 (diacylglycerol acyltransferase 2) in catalysing the de novo synthesis of triacylglycerols from newly synthesized fatty acids and nascent diacylglycerols identifies this enzyme as the link between the two. This places DGAT2 at the centre of carbohydrate-induced hypertriglyceridaemia and hepatic steatosis. This function is complemented, but not substituted for, by the ability of DGAT1 to rescue partial glycerides from complete hydrolysis. In peripheral tissues not normally considered to be lipogenic, synthesis of triacylglycerols may largely bypass DGAT2 except in hyperglycaemic/hyperinsulinaemic conditions, when induction of de novo fatty acid synthesis in these tissues may contribute towards increased triacylglycerol secretion (intestine) or insulin resistance (adipose tissue, and cardiac and skeletal muscle).

Ragaglitazar: The Pharmacokinetics, Pharmacodynamics, and Tolerability of a Novel Dual PPARα and γ Agonist in Healthy Subjects and Patients with Type 2 Diabetes

Ragaglitazar is a novel dual peroxisome proliferator-activated receptor (PPAR) alpha and gamma agonist intended to restore insulin sensitivity and correct diabetic dyslipidemia. These studies assessed single-dose pharmacokinetics and tolerability of ragaglitazar in healthy subjects, as well as multiple-dose pharmacokinetics, pharmacodynamics, and tolerability of ragaglitazar in healthy subjects and in patients with type 2 diabetes. Healthy subjects received a single oral dose (1-120 mg), and healthy subjects and type 2 diabetic patients received a loading dose and thereafter once-daily doses (0.5-16 mg) of ragaglitazar for 6 and 20 days, respectively. Ragaglitazar was rapidly absorbed (tmax: 1.5-1.7 h), with mean AUC0-24 h and Cmax proportional to dose after single and multiple dosing; t1/2 was 80 hours following a single dose and 104 hours in healthy subjects and 122 hours in patients after multiple dosing. Administration of 4 mg ragaglitazar to patients (n = 4) for 21 days resulted in mean decreases from baseline in fasting levels of plasma glucose (18%), C-peptide (18%), fructosamine (6%), triglycerides (36%), free fatty acids (49%), total cholesterol (11%), low-density lipoprotein (LDL) cholesterol (21%), and very low-density lipoprotein (VLDL) cholesterol (15%), as well as an increase in high-density lipoprotein (HDL) cholesterol (33%). Overall, ragaglitazar was well tolerated; with multiple dosing, there was a higher incidence of adverse events for patients that, at the highest dose level (16 mg), included peripheral edema and anemia.

Can LDL-cholesterol targets be achieved in a population at high risk? Results of the non-interventional study ACT II

OBJECTIVE

Lowering low-density lipoprotein cholesterol (LDL-C) levels can reduce vascular clinical endpoints in outcome studies. Despite this evidence, previous cross-sectional analyses reported a mean LDL-C target attainment of <50%. This non-interventional, longitudinal study aimed to asses the rate of target attainment by intensified LDL-C lowering therapy in a high-risk population under routine medical care.

DESIGN

This was an open-label, non-interventional, observational, non-comparative longitudinal study.

METHODS

A total of 1682 outpatients at high cardiovascular risk, not at LDL-C target despite statin therapy, were documented. Treating physicians administered an intensified therapy at their discretion. In all, 794 patients completed all the examinations at baseline after 3 and 12 months. The achieved LDL-C reductions was evaluated based on expert consensus reflecting the 2007 guidelines issued by the European Society of Cardiology (ESC) on cardiovascular disease prevention.

REGISTRATION

www.clinicaltrials.gov , identification number NCT 01381679 RESULTS: In the study, 40.3% achieved the individual LDL-C target of <.8 mmol/L (70 mg/dl) or <2.5 mmol/L (100 mg/dl); 73% received a simvastatin/ezetimibe fixed-dose combination; 3% received add-on ezetimibe and 23% statin therapy at maintained or increased doses; 1% received no drug treatment at all. LDL-C declined after 12 months by -31.0% (ratio 0.69, 95% CI 0.67-0.71, p<0.001), triglycerides by -11.8% (ratio 0.88, 95% CI 0.85-0.91, p<0.01) and high-density lipoprotein cholesterol (HDL-C) increased by 11.9% (ratio 1.12, 95% CI 1.10-1.14, p<0.01).

CONCLUSION

Intensified therapy was effective, but target attainment was still low at 40.3% or 13.9% with regard to the new 2011 guidelines issued by the European Atherosclerosis Society (EAS) and the ESC on dyslipidemias. Enhanced screening of LDL-C levels and the use of statins at highest tolerated dose and concomitant combination therapy is recommended in order to achieve LDL-C targets outlined by current guidelines. Limitations include the design as a non-interventional study. However, this study reflects real life conditions.

Dietary supplementation of n-3 PUFA reduces weight gain and improves postprandial lipaemia and the associated inflammatory response in the obese JCR:LA-cp rat

BACKGROUND

Postprandial dyslipidaemia occurs in obesity and insulin resistance (IR), and is associated with an increased risk of developing cardiovascular disease. We have recently established that the JCR:LA-cp rodent model develops postprandial dyslipidaemia concomitant with complications of the metabolic syndrome. Dietary n-3 polyunsaturated fatty acids (n-3 PUFAs) are proposed to modulate plasma lipids, serum hormone levels, lipoprotein metabolism and the inflammatory state; however, results remain inconsistent during conditions of IR.

AIM

To assess the acute metabolic and inflammatory effects of dietary fish oil supplementation on existing postprandial dyslipidaemia in the JCR:LA-cp model.

METHODS

JCR:LA-cp rats (14 weeks of age) were fed either a control, isocaloric, lipid balanced diet (15% w/w total fat, 1.0% cholesterol, P:S ratio 0.4), a lipid balanced diet with 5% n-3 PUFA [fish oil derived eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA)] or a lipid balanced diet with 10% n-3 PUFA for 3 weeks. Fasting plasma lipid, cytokine levels, postprandial chylomicron (apoB48) metabolism and the postprandial inflammatory response [haptoglobin and lipopolysaccharide binding protein (LBP)] were assessed following a standardized 'oral fat challenge'.

RESULTS

n-3 PUFA treatment resulted in a significant improvement (i.e. decrease) in the postprandial response for triglyceride (45%) (p < 0.05), apoB48 (45%) (p < 0.03) and LBP (33%) (p < 0.05) compared to controls (measured as area under the clearance curve). In contrast, we observed a significant elevation in postprandial haptoglobin (165%) (p < 0.001) in obese rats supplemented with 10% n-3 PUFA. Treatment with 5% n-3 PUFA in the JCR:LA-cp obese animals resulted in a complementary decrease in total body weight gain (6%) (p < 0.001) and an increase (i.e. improvement) in adiponectin (33%) (p < 0.05) compared to controls, without a concomitant reduction in food intake.

CONCLUSION

Acute dietary n-3 PUFA dietary supplementation can improve fasting as well as postprandial lipid metabolism and components of the associated inflammatory response in the JCR:LA-cp rat. Further, moderate dose n-3 PUFA supplementation may reduce corresponding body weight during conditions of hypercholesterolaemia and/or modulate inflammation associated with obesity and the metabolic syndrome.

Managing diabetic dyslipidemia: beyond statin therapy

Cardiovascular disease is a significant cause of morbidity and mortality in patients with diabetes mellitus. The lipid profile of type 2 diabetes mellitus is characterized by increased triglycerides (TGs), decreased high-density lipoprotein cholesterol (HDL-C), increased very low density lipoproteins (VLDLs), and small, dense low-density lipoprotein particles, the combination of which is highly atherogenic. In diabetic patients, current treatment guidelines target low-density lipoprotein cholesterol (LDL-C) <or= 100 mg/dL with statins. In patients with elevated TGs, non-HDL-C is considered a secondary target of therapy. Despite the use of statin therapy in diabetes, a significant number of fatal and nonfatal coronary heart disease (CHD) events still occur, indicating the need to target other modifiable risk factors for CHD, including high TGs and low HDL-C.

The influence of PON1 192 polymorphism on endothelial function in diabetic subjects with or without hypertension

Hypertension and type 2 diabetes mellitus (T2DM) cause endothelial dysfunction probably through increased oxidant stress. Paraoxonase (PON1) is an high-density lipoprotein (HDL)-linked anti-oxidant enzyme whose capacity is influenced by a genetic polymorphism at codon 192. In the present study we have investigated the role of PON1 polymorphism on endothelial function in subjects with T2DM with or without hypertension. Three groups of male subjects were enrolled: 65 healthy control subjects without T2DM or hypertension (CON), 51 with only T2DM (DM), and 67 with both hypertension and T2DM (HYP+DM). The PON1 Gln192Arg polymorphism was determined by polymerase chain reaction (PCR) amplification and restriction analysis. Endothelial function was evaluated as flow-mediated vasodilatation (FMD) of the brachial artery after forearm ischemia. Data were analyzed according to the presence or absence of the Arg allele. Subjects with T2DM had markedly impaired FMD, compared with those of the CON group. In the CON and HYP+DM groups no difference was observed in FMD between subjects homozygous for the Gln allele and those carrying the Arg allele. In the DM group FMD was lower among those carrying the Arg allele compared with Gln/Gln homozygotes (2.1+/-2.4% vs. 6.2+/-5.2%, p=0.002). In conclusion, the present findings demonstrated that FMD was less impaired in normotensive diabetic subjects homozygous for the Gln allele, consistent with the notion that this isoform has a more effective antioxidant action that serves to protect circulating low-density lipoprotein (LDL). Hypertension seems to abolish the protective effect of the Gln isoform. These findings, however, warrant further investigation to clarify their clinical import.

Intensive insulin therapy in the intensive care unit: update on clinical impact and mechanisms of action

OBJECTIVE

Hyperglycemia is a common feature of the critically ill and has been associated with increased mortality. In this review, we give an overview of studies associating critical illness-induced hyperglycemia with adverse outcome and describe how mortality and morbidity are affected when blood glucose levels are strictly controlled to normoglycemia with intensive insulin therapy.

RESULTS

Maintaining normoglycemia with intensive insulin therapy improves survival rates and reduces morbidity in prolonged critically ill patients in both surgical and medical intensive care units (ICUs), as shown by 2 large randomized controlled studies. Prevention of cellular glucose toxicity by strict glycemic control appears to play a predominant role, but other metabolic and nonmetabolic effects of insulin also seem to contribute to the clinical benefits of this therapy.

CONCLUSION

These data support the generalized implementation of a strict blood glucose control management with intensive insulin therapy in adult surgical as well as medical ICU patients.

Postprandial lipemia: an under-recognized atherogenic factor in patients with diabetes mellitus

Atherosclerotic disease is the leading cause of both morbidity and mortality in patients with type 2 diabetes. In these patients, postprandial dyslipidemia include not only quantitative but also qualitative abnormalities of lipoproteins which are potentially atherogenic and seems to be a significant risk factor for cardiovascular disease since there is evidence that it results in endothelial dysfunction and enhanced oxidative stress. The most common pattern of postprandial dyslipidemia in diabetes consists of high concentrations of triglycerides, higher VLDLs production by the liver and a decrease in their clearance, a predominance of small dense LDL particles, and reduced levels of HDL. The cause of this postprandial dyslipidemia in diabetes is complex and involves a variety of factors including hyperinsulinemia, insulin resistance, hyperglycemia and disturbed fatty acid metabolism. Numerous clinical studies have shown that postprandial dyslipidemia is associated with endothelial dysfunction in type 2 diabetes and with alterations in other surrogate markers in the cascade of atherosclerosis. Current published guidelines indicate that in diabetics the primary lipid target is LDL<100 mg/dL (70 mg/dL in very high-risk patients) and the most appropriate class of drugs are statins although the issue of postprandial dyslipidemia has not been specifically addressed so far. Moreover, several other classes of medications (fibrates, niacin and antidiabetic drugs) as well as non-pharmacological interventions (i.e. diet, smoking cessation and exercise) can be used to treat lipid and lipoprotein abnormalities associated with insulin resistance and type 2 diabetes. These type of interventions may be more appropriate to ameliorate postprandial dyslipidemia. However, this remains to be confirmed on clinical grounds.

Risks and benefits of nutritional support during critical illness

Critically ill patients who depend on intensive care for more than a few days reveal profound erosion of lean body mass, which is thought to contribute to high morbidity and mortality. Despite a shortfall of evidence that supplemental feeding actually alters clinical outcome of these life-threatening disease states, this observation evoked an almost universal, albeit often inappropriate, use of nutritional support (NS) in the critically ill, administered via the parenteral or the enteral route. Lack of knowledge and overenthusiasm subsequently resulted in complications associated with both parenteral nutrition (PN) and enteral nutrition (EN), which led to the standing controversy over which should be preferred. With time, however, it became clear that EN and PN are not mutually exclusive and that critically ill patients requiring NS should be fed according to the functional status of the gastrointestinal tract. In addition, tight blood glucose control with insulin is advised in fed critically ill patients because overall metabolic control appears to surpass any outcome benefit attributed to the route of feeding. Recently, various special nutritional formulas have been suggested to prevent or treat multiorgan failure in the critically ill, among other pathways via modulation of immune function. Although special nutritional formulas may be promising in a variety of clinical settings, based on currently available data, these cannot be recommended for routine use in critically ill patients.

Overproduction of intestinal lipoprotein containing apolipoprotein B-48 in Psammomys obesus: impact of dietary n-3 fatty acids

AIMS/HYPOTHESIS

Emerging evidence underscores the important role of the small intestine in the pathogenesis of dyslipidaemia in insulin resistance and type 2 diabetes. We therefore tested the hypothesis that n-3 fatty acids improve the various events governing intra-enterocyte lipid transport in Psammomys obesus gerbils, a model of nutritionally induced metabolic syndrome.

MATERIALS AND METHODS

Experiments were carried out on Psammomys obesus gerbils that were assigned to an isocaloric control diet and a diet rich in fish oil for 6 weeks.

RESULTS

Increased dietary intake of fish oil lowered body weight and improved hyperglycaemia and hyperinsulinaemia. It simultaneously decreased de novo intestinal lipogenesis and lipid esterification of the major lipid classes, e.g. triglycerides, phospholipids and cholesteryl esters, particularly in insulin-resistant and diabetic animals. Accordingly, lessened activity of monoacylglycerol and diacylglycerol acyltransferase was recorded. As assessed in cultured jejunal explants incubated with either [(14)C]-oleic acid or [(35)S]-methionine, fish oil feeding resulted in diminished triglyceride-rich lipoprotein assembly and apolipoprotein (apo) B-48 biogenesis, respectively. The mechanisms did not involve apo B-48 transcription or alter the gene expression and activity of the critical microsomal triglyceride transfer protein. Rather, the suppressed production of apo B-48 by n-3 fatty acids was associated with intracellular proteasome-mediated posttranslational downregulation in insulin-resistant and diabetic animals.

CONCLUSIONS/INTERPRETATION

Our data highlight the beneficial impact of n-3 fatty acids on adverse effects of the metabolic syndrome and emphasise their influence on intestinal lipid transport, an effect which may limit postprandial lipaemia and the risk of atherosclerosis.

Glucose metabolism and insulin therapy

Hyperglycemia is a common feature of the critically ill patient and has been associated with increased mortality. Maintaining normoglycemia with insulin therapy improves survival and reduces morbidity in surgical ICU patients, as shown by a large randomized controlled study. Prevention of glucose toxicity by strict glycemic control but also other metabolic and non-metabolic effects of insulin contribute to these clinical benefits.

Effects of fluvastatin slow-release (XL 80 mg) versus simvastatin (20 mg) on the lipid triad in patients with type 2 diabetes

The lipid triad is the association of small, dense (sd) low-density lipoprotein (LDL), low high-density lipoprotein (HDL), and hypertriglyceridemia, all of which play a role in coronary artery disease in patients with type 2 diabetes. Although statins have demonstrated clear positive effects on cardiovascular morbidity/mortality in patients with diabetes and on single components of the lipid triad, it remains controversial whether they affect all components of the triad in these patients. Therefore, we performed a single-center, parallel-group, prospective, randomized, open-label, blinded-endpoint (PROBE)-type comparison of fluvastatin extended-release (XL) 80 mg (n=48) and simvastatin 20 mg (n=46), each given once daily for 2 months to patients with type 2 diabetes with the lipid triad, who were enrolled after a 1-month lifestyle modification and dietary intervention program. After fluvastatin therapy, LDL (-51%; P<.01), apolipoprotein B (ApoB; -33%; P<.01), intermediate-density LDL (idLDL) (-14.3%; P<.05), sdLDL (-45%; P<.01), and triglycerides (-38%; P<.01) were significantly decreased, and HDL (+14.3%; P<.05) and apolipoprotein A-I (ApoA-I; +7%; P<.05) were increased; large buoyant (lb) LDL did not change (P=NS). Simvastatin therapy decreased LDL (-55.1%; P<.01), ApoB (-46%; P<.01), lbLDL (-33.3%; P<.05), idLDL (-22.7%; P<.05), sdLDL (-33.3%; P<.05), and triglycerides (-47.9%; P<.01); HDL was not changed (P=NS) after simvastatin, but ApoA-I was increased (+11.3%; P<.01). HDL increases (P<.01) and sdLDL decreases (P<.01) were significantly greater after fluvastatin compared with simvastatin therapy; LDL, triglycerides, ApoB, and idLDL changes were similar after both therapies (P=NS), and lbLDL decreases were greater with simvastatin therapy (P<.05). With both treatments, classic mean LDL and ApoB target levels were achieved in most patients. We conclude that the lipid triad can be controlled with fluvastatin XL 80 mg in patients with type 2 diabetes.

Tesaglitazar, a dual PPARα/γ agonist, ameliorates glucose and lipid intolerance in obese Zucker rats

Insulin resistance, impaired glucose tolerance, high circulating levels of free fatty acids (FFA), and postprandial hyperlipidemia are associated with the metabolic syndrome, which has been linked to increased risk of cardiovascular disease. We studied the metabolic responses to an oral glucose/triglyceride (TG) (1.7/2.0 g/kg lean body mass) load in three groups of conscious 7-h fasted Zucker rats: lean healthy controls, obese insulin-resistant/dyslipidemic controls, and obese rats treated with the dual peroxisome proliferator-activated receptor α/γ agonist, tesaglitazar, 3 μmol·kg−1·day−1for 4 wk. Untreated obese Zucker rats displayed marked insulin resistance, as well as glucose and lipid intolerance in response to the glucose/TG load. The 2-h postload area under the curve values were greater for glucose (+19%), insulin (+849%), FFA (+53%), and TG (+413%) compared with untreated lean controls. Treatment with tesaglitazar lowered fasting plasma glucose, improved glucose tolerance, substantially reduced fasting and postload insulin levels, and markedly lowered fasting TG and improved lipid tolerance. Fasting FFA were not affected, but postprandial FFA suppression was restored to levels seen in lean controls. Mechanisms of tesaglitazar-induced lowering of plasma TG were studied separately using the Triton WR1339 method. In anesthetized, 5-h fasted, obese Zucker rats, tesaglitazar reduced hepatic TG secretion by 47%, increased plasma TG clearance by 490%, and reduced very low-density lipoprotein (VLDL) apolipoprotein CIII content by 86%, compared with obese controls. In conclusion, the glucose/lipid tolerance test in obese Zucker rats appears to be a useful model of the metabolic syndrome that can be used to evaluate therapeutic effects on impaired postprandial glucose and lipid metabolism. The present work demonstrates that tesaglitazar ameliorates these abnormalities and enhances insulin sensitivity in this animal model.

Intestinal microsomal triglyceride transfer protein in type 2 diabetic and non-diabetic subjects: the relationship to triglyceride-rich postprandial lipoprotein composition

BACKGROUND

Microsomal triglyceride transfer protein (MTP) is responsible for the assembly of the triglyceride-rich lipoproteins (TRLs) and is increased in diabetic animal models. Human intestinal MTP expression has not been previously reported. This study examined the relationship between intestinal MTP gene expression and postprandial TRL composition in diabetic and non-diabetic subjects. Since the MTP promoter region has a sterol response element the effect of statins on intestinal MTP mRNA was analysed.

METHODS

Twenty-seven diabetic and 24 non-diabetic subjects were examined. Duodenal biopsies were taken during gastroscopy and MTP mRNA was measured by RNase protection assay. Postprandial lipoprotein composition was determined.

RESULTS

Diabetic subjects had significantly higher MTP mRNA than non-diabetic subjects. Statin therapy was associated with lower MTP mRNA in both groups. In the untreated diabetic patients compared to the untreated non-diabetic patients MTP mRNA was 25.0 +/- 25.1 amol/microg versus 13.1 +/- 5.6 amol/microg total RNA (p < 0.05). In the statin-treated diabetic group compared to statin-treated non-diabetic group MTP mRNA was 17.7 +/- 8.6 amol/microg versus 5.8 +/- 4.1 amol/microg total RNA (p < 0.05). In the whole group there was a positive correlation between the MTP mRNA and postprandial chylomicron cholesterol/B48 (r = 0.36, p < 0.01).

CONCLUSIONS

This is the first study to demonstrate increased MTP expression in diabetic subjects. MTP mRNA expression was lower in statin-treated patients confirming the suggestion that the insulin and sterol response elements of the MTP gene are important regulators of MTP transcription in diabetes. Our results show that MTP plays a central role in regulating the cholesterol content of the chylomicron particle.

Postprandial hypertriglyceridemia and carotid intima-media thickness in north Indian type 2 diabetic subjects

Hypertriglyceridemia is an important risk factor for coronary heart disease (CHD) and in the development of atherosclerosis, especially in subgroups of the population like those with type 2 diabetes. Although triglycerides are generally increased in the postprandial period, the association between postprandial triglyceride (ppTG) levels and atherosclerosis has not been investigated in north Indian type 2 diabetic subjects known to have a very high prevalence rate of premature CHD and insulin resistance. To investigate the role of ppTG levels in atherosclerosis in type 2 diabetes, we examined the correlation between ppTG levels and carotid intima-media thickness (IMT). Carotid IMT was determined by high resolution B-mode ultrasonography in 86 newly detected type 2 diabetic subjects (1-12 months duration) having good glycemic control (HbA(1C)<7%) and 45 non-diabetic subjects matched according to age and body mass index (BMI). Plasma glucose, insulin, total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides were measured after overnight fasting. Plasma insulin and glucose were also measured 2h and plasma triglycerides 4h after breakfast. The mean carotid IMT in diabetic subjects was higher than those in non-diabetic subjects (0.77+/-0.15 mm versus 0.53+/-0.16 mm, P<0.001). Based on the fasting and postprandial triglyceride levels, the diabetic subjects were divided into three groups: normo-normo (NN); normo-hyper (NH); hyper-hyper (HH) [NN: fTG<1.70 mmol/L and ppTG<2.30 mmol/L; NH: fTG<1.70 mmol/L and ppTG>2.30 mmol/L; HH: fTG>1.70 mmol/L and ppTG>2.30 mmol/L]. Carotid IMT was significantly increased in the NH (0.79+/-0.09 mm) and HH (0.82+/-0.06 mm) groups compared with the NN group (0.59+/-0.09 mm, P<0.001). Although ppTG, age, fasting LDL-cholesterol, HOMA-estimated insulin resistance, HbA(1C) were all independently correlated with carotid IMT, age and ppTG levels had the strongest statistical influence (P<0.002).

Is atherosclerosis in diabetes and impaired fasting glucose driven by elevated LDL cholesterol or by decreased HDL cholesterol?

OBJECTIVE

To evaluate the atherogenicity of lipids in coronary patients with normal fasting glucose (NFG), impaired fasting glucose (IFG), and type 2 diabetes.

RESEARCH DESIGN AND METHODS

Serum lipid values, the presence of angiographic coronary artery disease (CAD) at baseline, and the incidence of vascular events over 2.3 years were recorded in 750 consecutive patients undergoing coronary angiography.

RESULTS

Triglycerides significantly (P < 0.001) increased and HDL cholesterol (P < 0.001) as well as LDL particle diameter (P < 0.001) significantly decreased from subjects with NFG <5.6 mmol/l (n = 272) over patients with IFG > or =5.6 mmol/l (n = 314) to patients with type 2 diabetes (n = 164). Factor analysis revealed two factors in the lipid profiles of our patients: triglycerides, HDL cholesterol, apolipoprotein A1, and LDL particle diameter loaded high on an HDL-related factor, and total cholesterol, LDL cholesterol, and apolipoprotein B loaded high on an LDL-related factor. In patients with type 2 diabetes, the HDL-related factor (odds ratio 0.648 [95% CI 0.464-0.904]; P = 0.011), but not the LDL-related factor (0.921 [0.677-1.251]; P = 0.597), was associated with significant coronary stenoses > or =50%. Consistently, in the prospective study, the HDL-related factor (0.708 [0.506-0.990]; P = 0.044), but not the LDL-related factor (1.362 [0.985-1.883]; P = 0.061), proved significantly predictive for vascular events in patients with type 2 diabetes.

CONCLUSIONS

The low HDL cholesterol/high triglyceride pattern is associated with the degree of hyperglycemia. In coronary patients with type 2 diabetes, this pattern correlates with the prevalence of CAD and significantly predicts the incidence of vascular events.

How does blood glucose control with insulin save lives in intensive care?

Patients requiring prolonged intensive care are at high risk for multiple organ failure and death. Insulin resistance and hyperglycemia accompany critical illness, and the severity of this "diabetes of stress" reflects the risk of death. Recently it was shown that preventing hyperglycemia with insulin substantially improves outcome of critical illness. This article examines some potential mechanisms underlying prevention of glucose toxicity as well as the effects of insulin independent of glucose control. Unraveling the molecular mechanisms will provide new insights into the pathogenesis of multiple organ failure and open avenues for novel therapeutic strategies.

Association between LDL particle size and postprandial increase of remnant-like particles in Japanese type 2 diabetic patients

Small, dense LDL, as well as chylomicron- and VLDL-remnant lipoproteins, are known to be important risk factors for coronary heart disease in patients with type 2 diabetes mellitus. The aim of this study was to clarify the relationship between LDL particle size and postprandial remnant lipoprotein levels in Japanese type 2 diabetic patients. Forty-six patients with type 2 diabetes mellitus were divided into tertiles according to LDL particle size. The peak LDL particle diameter was <26.30 nm in tertile 1, 26.30-26.85 nm in tertile 2, and >26.85 nm in tertile 3. After a test meal, tertile 1 had a significantly greater increment of triglycerides (TG), remnant-like particle (RLP)-TG, and RLP-cholesterol (RLP-C) than tertiles 2 and 3. There was a negative correlation between LDL particle size and the postprandial increases of TG, RLP-TG, and RLP-C. These results indicate that smaller sized LDL particles may be a marker of fasting state for an exaggerated postprandial increase of remnant lipoproteins as well as an increase of TG-rich lipoproteins.

The endocrine system during sepsis

Endocrinopathy during sepsis can manifest as hyperglycemia and insulin resistance or as insufficient production of either adrenal corticosteroids or vasopressin. The results of a recent large clinical trial have demonstrated that tight glycemic control with insulin can confer survival benefit to selected intensive care unit patients. Relative impairment of adrenocortical reserve has been suggested to be an important contributor to the pathogenesis of shock in sepsis. Replacement doses of glucocorticoids and mineralocorticoids have been associated with improved survival in the subset of patients with blunted results on adrenocorticotropin hormone stimulation tests. Posterior pituitary production of vasopressin is diminished in septic shock while sensitivity to its vasopressor effects is enhanced. Clinical trials are underway to determine whether administration of vasopressin can improve outcomes in patients with septic shock. Whether the euthyroid sick syndrome represents an adaptive or a maladaptive response to severe illness remains unclear.

How does blood glucose control with insulin save lives in intensive care?

Patients requiring prolonged intensive care are at high risk for multiple organ failure and death. Insulin resistance and hyperglycemia accompany critical illness, and the severity of this "diabetes of stress" reflects the risk of death. Recently it was shown that preventing hyperglycemia with insulin substantially improves outcome of critical illness. This article examines some potential mechanisms underlying prevention of glucose toxicity as well as the effects of insulin independent of glucose control. Unraveling the molecular mechanisms will provide new insights into the pathogenesis of multiple organ failure and open avenues for novel therapeutic strategies.

Regulation of triacylglycerol hydrolase expression by dietary fatty acids and peroxisomal proliferator-activated receptors

Triacylglycerol hydrolase (TGH) is an enzyme that catalyzes the lipolysis of intracellular stored triacylglycerol (TG). Peroxisomal proliferator-activated receptors (PPAR) regulate a multitude of genes involved in lipid homeostasis. Polyunsaturated fatty acids (PUFA) are PPAR ligands and fatty acids are produced via TGH activity, so we studied whether dietary fats and PPAR agonists could regulate TGH expression. In 3T3-L1 adipocytes, TGH expression was increased 10-fold upon differentiation, compared to pre-adipocytes. 3T3-L1 cells incubated with a PPARgamma agonist during the differentiation process resulted in a 5-fold increase in TGH expression compared to control cells. Evidence for direct regulation of TGH expression by PPARgamma could not be demonstrated as TGH expression was not affected by a 24-h incubation of mature 3T3-L1 adipocytes with the PPARgamma agonist. Feeding mice diets enriched in fatty acids for 3 weeks did not affect hepatic TGH expression, though a 3-week diet enriched in fatty acids and cholesterol increased hepatic TGH expression 2-fold. Two weeks of clofibrate feeding did not significantly affect hepatic TGH expression or microsomal lipolytic activities in wild-type or PPARalpha-null mice, indicating that PPARalpha does not regulate hepatic TGH expression. Therefore, TGH expression does not appear to be directly regulated by PPARs or fatty acids in the liver or adipocytes.

Clinical potential of insulin therapy in critically ill patients

Stress of critical illness is often accompanied by hyperglycaemia, whether or not the patient has a history of diabetes mellitus. This has been considered to be part of the adaptive metabolic response to stress. The level of hyperglycaemia in patients with acute myocardial infarction (MI) or stroke upon admission to the hospital has been related to the risk of adverse outcome. However, until recently, there was no evidence of a causal relationship and thus stress-induced hyperglycaemia was only treated with exogenous insulin when it exceeded 12 mmol/L (220 mg/dL). In patients with known diabetes, even higher levels were often tolerated. Recently, new data became available in support of another approach. In this review, we focus on the new evidence and the clinical aspects of managing hyperglycaemia with insulin in critically ill patients, drawing a parallel with diabetes management. Particularly, the 'Diabetes and Insulin-Glucose infusion in Acute Myocardial Infarction (DIGAMI) study' and the 'insulin in intensive care study' have provided novel insights. The DIGAMI study showed that in patients with diabetes, controlling blood glucose levels below 12 mmol/L for 3 months after acute MI improves long-term outcome. In the recent study of predominantly surgical intensive care patients, the majority of whom did not previously have diabetes, it was shown that an even tighter control of blood glucose with exogenous insulin, aiming for normoglycaemia, dramatically improved outcome. Indeed, in this large prospective, randomised, controlled study, 1548 intensive care patients had been randomly allocated to either the conventional approach, with insulin infusion started only when blood glucose levels exceeded 12 mmol/L, or intensive insulin therapy, with insulin infused to maintain blood glucose at a level of 4.5-6.1 mmol/L (80-110 mg/dL). Intensive insulin therapy reduced intensive care mortality by more than 40% and also decreased a number of morbidity factors including acute renal failure, polyneuropathy, ventilator-dependency and septicaemia. Future studies will be needed to further unravel the mechanisms that explain the beneficial effects of this simple and cost-saving intervention. Although available evidence supports implementation of intensive insulin therapy in surgical intensive care, the benefit for other patient populations, such as patients on medical intensive care units or hospitalised patients who do not require intensive care but who do present with stress-induced hyperglycaemia, remains to be investigated.

Diabetic dyslipidaemia: from basic research to clinical practice

The recognition that the increase of plasma triglyceride rich lipoproteins (TRLs) is associated with multiple alterations of other lipoproteins species that are potentially atherogenic has expanded the picture of diabetic dyslipidaemia. The discovery of heterogeneity within major lipoprotein classes VLDL, LDL and HDL opened new avenues to reveal the specific pertubations of diabetic dyslipidaemia. The increase of large VLDL 1 particles in Type 2 diabetes initiates a sequence of events that generates atherogenic remnants, small dense LDL and small dense HDL particles. Together these components comprise the atherogenic lipid triad. Notably the malignant nature of diabetic dyslipidaemia is not completely shown by the lipid measures used in clinical practice. The key question is what are the mechanisms behind the increase of VLDL 1 particles in diabetic dyslipidaemia? Despite the advances of recent years, our understanding of VLDL assembly and secretion is still surprisingly incomplete. To date it is still unclear how the liver is able to regulate the amount of triglycerides incorporated into VLDL particles to produce either VLDL 1 or VLDL 2 particles. The current evidence suggests that the machinery driving VLDL assembly in the liver includes (i) low insulin signalling via PI-3 kinase pathway that enhances lipid accumulation into "nascent " VLDL particles (ii) up-regulation of SREBP-1C that stimulates de novo lipogenesis and (iii) excess availability of "polar molecules" in hepatocytes that stabilizes apo B 100. Recent data suggest that all these steps could be fundamentally altered in Type 2 diabetes explaining the overproduction of VLDL apo B as well as the ability of insulin to suppress VLDL 1 apo B production in Type 2 diabetes. Recent discoveries have established the transcription factors including PPARs, SREBP-1 and LXRs as the key regulators of lipid assembly in the liver. These observations suggest these factors as a new target to tailor more efficient drugs to treat diabetic dyslipidaemia.

NAD (P) H oxidase p22 phox C242T polymorphism affects LDL particle size and insulin resistance in Japanese subjects

Elevated cardiovascular risk is associated with an increased number of small, dense low-density lipoprotein (LDL) particles, which exhibit increased susceptibility to lipid oxidation, however, the mechanism determining LDL particle size has never been fully elucidated. We have examined the association between the C242T polymorphism of the p22 phox gene, which is a small subunit of vascular NAD(P)H oxidase, and both LDL particle size and clinical characteristics in 260 healthy subjects. Peak LDL particle diameter (LDL-PPD) was measured by continuous disk polyacrylamide gel electrophoresis. Twenty-one of the 217 subjects with the CC genotype showed pattern B (median LDL-PPD under 25.5 nm), whereas, none of the 43 subjects with TC + TT genotypes showed pattern B. The pattern B fraction was significantly larger in the CC group than in the TC + TT group (p = 0.030). The subjects with the CC genotype also showed a significantly higher fasting glucose level, plasma insulin level, and insulin resistance index of homeostasis model assessment (HOMA-R) than those with the TC + TT genotype. Our data demonstrate that variation in the small NAD(P)H oxidase subunit p22 phox gene substantially influences LDL particle size and may also reflect differences in the insulin sensitivity of non-diabetic subjects.

Influence of peroxisome proliferator-activated receptor alpha agonists on the intracellular turnover and secretion of apolipoprotein (Apo) B-100 and ApoB-48

The peroxisome proliferator-activated receptor (PPAR) alpha agonist WY 14,643 increased the secretion of apolipoprotein (apo) B-100, but not that of apoB-48, and decreased triglyceride biosynthesis and secretion from primary rat hepatocytes. These effects resulted in decreased secretion of apoB-100-very low density lipoprotein (VLDL) and an increased secretion of apoB-100 on low density lipoproteins/intermediate density lipoproteins. ApoB-48-VLDL was also replaced by more dense particles. The proteasomal inhibitor lactacystin did not influence the recovery of apoB-100 or apoB-48 in primary rat hepatocytes, indicating that co-translational (proteasomal) degradation is of less importance in these cells. Treatment with WY 14,643 made the recovery of apoB-100 sensitive to lactacystin, most likely reflecting the decreased biosynthesis of triglycerides. The PPAR alpha agonist induced a significant increase in the accumulation of pulse-labeled apoB-100 even after a short pulse (2-5 min). There was also an increase in apoB-100 nascent polypeptides, indicating that the co-translational degradation of apoB-100 was inhibited. However, a minor influence on an early posttranslation degradation cannot be excluded. This decreased co-translational degradation of apoB-100 explained the increased secretion of the protein. The levels of apoB-48 remained unchanged during these pulse-chase experiments, and albumin production was not affected, indicating a specific effect of PPAR alpha agonists on the co-translational degradation of apoB-100. These findings explain the difference in the rate of secretion of the two apoB proteins seen after PPAR alpha activation. PPAR alpha agonists increased the expression and biosynthesis of liver fatty acid-binding protein (LFABP). Increased expression of LFABP by transfection of McA-RH7777 cells increased the secretion of apoB-100, decreased triglyceride biosynthesis and secretion, and increased PPAR alpha mRNA levels. These findings suggest that PPAR alpha and LFABP could interact to amplify the effect of endogenous PPAR alpha agonists on the assembly of VLDL.