Different inverse association of large high-density lipoprotein subclasses with exacerbation of insulin resistance and incidence of type 2 diabetes: The Nagahama study

Correlation Between Glycolipid Metabolism Levels and Diabetic Retinopathy in Patients with Type 2 Diabetes Mellitus

Purpose

We investigate the correlation between glucose and lipid metabolism and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM) and its diagnostic and predictive value.

Patients and Methods

A retrospective analysis involved 620 patients diagnosed with T2DM, categorized into two groups based on fundus examination results: the non-diabetic retinopathy group (NDR, n=340) and the diabetic retinopathy group (DR, n=280). We collected baseline patient data, calculated the ratio of glycated hemoglobin (HbA1c) to high-density lipoprotein cholesterol (HDL-C), and analyzed its association with Type 2 Diabetic Retinopathy.

Results

HbA1c/HDL-C in DR group exhibited significantly higher than the NDR group (P<0.001). Mantel-Haenszel's chi-square trend analysis indicated a notable linear trend (P<0.001) between HbA1c/HDL-C and DR. HbA1c/HDL-C revealed moderate positive correlations with DR, r=0.342, P<0.001. Binary logistic regression analysis showed systolic blood pressure (SBP), diabetes course, fasting blood glucose (FBG) and HbA1c/HDL-C as independent risk factors for DR in T2DM patients. Restrictive cubic spline analysis demonstrated a significant nonlinear relationship between HbA1c/HDL-C and DR (P total trend <0.001, P nonlinear = 0.0196). ROC curve analysis identified that HbA1c/HDL-C had the highest diagnostic accuracy for DR, with an area under the ROC curve (AUC) of 0.711, 53.2% sensitivity, and 78.2% specificity.

Conclusion

Our study shows that HbA1c/HDL-C is an independent risk factor for DR in patients with type 2 diabetes. HbA1c/HDL-C has good diagnostic value for DR and can be used as a biological index for early screening of DR.

Type 2 Diabetes and HDL Dysfunction: A Key Contributor to Glycemic Control

High-density lipoproteins (HDL) have been shown to exert multiple cardioprotective and antidiabetic functions, such as their ability to promote cellular cholesterol efflux and their antioxidant, anti-inflammatory, and antiapoptotic properties. Type 2 diabetes (T2D) is usually associated with low high-density lipoprotein cholesterol (HDL-C) levels as well as with significant alterations in the HDL composition, thereby impairing its main functions. HDL dysfunction also negatively impacts both pancreatic β-cell function and skeletal muscle insulin sensitivity, perpetuating this adverse self-feeding cycle. The impairment of these pathways is partly dependent on cellular ATP-binding cassette transporter (ABC) A1-mediated efflux to lipid-poor apolipoprotein (apo) A-I in the extracellular space. In line with these findings, experimental interventions aimed at improving HDL functions, such as infusions of synthetic HDL or lipid-poor apoA-I, significantly improved glycemic control in T2D patients and experimental models of the disease. Cholesteryl ester transfer protein (CETP) inhibitors are specific drugs designed to increase HDLC and HDL functions. Posthoc analyses of large clinical trials with CETP inhibitors have demonstrated their potential anti-diabetic properties. Research on HDL functionality and HDL-based therapies could be a crucial step toward improved glycemic control in T2D subjects.

A decreased level of high-density lipoprotein is a possible risk factor for type 2 diabetes mellitus: A review

Introduction

Type 2 diabetes mellitus (T2DM) is characterized primarily by dyslipidemia and hyperglycemia due to insulin resistance. High-density lipoprotein (HDL) play a significant role in preventing the incidence of dyslipidemia and its complications. HDL has different protective functions, such as reducing oxidation, vascular inflammation, and thrombosis; additionally, its anti-diabetic role is one of the most significant recent discoveries about HDL and some of its constituent lipoproteins.

Methods

This research reviews ongoing studies and preliminary investigations into the assessment of relation between decreased level of HDL and T2DM.

Results

The levels of HDL and its functions contribute to glucose hemostasis and the development of T2DM through four possible mechanisms, including insulin secretion by beta cells, peripheral insulin sensitivity, non-insulin-dependent glucose uptake, and adipose tissue metabolic activity. Additionally, the anti-oxidant properties of HDL protect beta cells from apoptosis caused by oxidative stress and inflammation induced by low-density lipoprotein, which facilitate insulin secretion.

Conclusion

Therefore, HDL and its compositions, especially Apo A-I, play an important role in regulating glucose metabolism, and decreased levels of HDL can be considered a risk factor for DM. Different factors, such as hypoalphalipoproteinemia that manifests as a consequence of genetic factors, such as Apo A-I deficiency, as well as secondary causes arising from lifestyle choices and underlying medical conditions that decrease the level of HDL, could be associated with DM. Moreover, intricate connections between HDL and diabetic complications extend beyond glucose metabolism to encompass complications like cardiovascular disease and kidney disease. Therefore, the exact interactions between HDL level and DM should be evaluated in future studies.

High-Density Lipoprotein Alterations in Type 2 Diabetes and Obesity

Alterations affecting high-density lipoproteins (HDLs) are one of the various abnormalities observed in dyslipidemia in type 2 diabetes mellitus (T2DM) and obesity. Kinetic studies have demonstrated that the catabolism of HDL particles is accelerated. Both the size and the lipidome and proteome of HDL particles are significantly modified, which likely contributes to some of the functional defects of HDLs. Studies on cholesterol efflux capacity have yielded heterogeneous results, ranging from a defect to an improvement. Several studies indicate that HDLs are less able to inhibit the nuclear factor kappa-B (NF-κB) proinflammatory pathway, and subsequently, the adhesion of monocytes on endothelium and their recruitment into the subendothelial space. In addition, the antioxidative function of HDL particles is diminished, thus facilitating the deleterious effects of oxidized low-density lipoproteins on vasculature. Lastly, the HDL-induced activation of endothelial nitric oxide synthase is less effective in T2DM and metabolic syndrome, contributing to several HDL functional defects, such as an impaired capacity to promote vasodilatation and endothelium repair, and difficulty counteracting the production of reactive oxygen species and inflammation.

The relationship between the ratio of gamma-glutamyltransferase to high-density lipoprotein cholesterol and the risk of diabetes mellitus using publicly available data: a secondary analysis based on a longitudinal study in Japan

BACKGROUND

The ratio of gamma-glutamyltransferase to high-density lipoprotein cholesterol (GGT/HDL-C) has been highlighted in nonalcoholic fatty liver disease (NAFLD) by previous studies. However, there have been fewer investigations into the correlation between the GGT/HDL-C ratio and type 2 diabetes mellitus (T2DM) incidence. Our secondary analysis used published data from a Japanese population and aimed to investigate the role of the GGT/HDL-C ratio in the incidence of T2DM.

METHODS

The research was a longitudinal cohort study completed by Okamura, Takuro et al. We obtained the data from the DATADRYAD website and used it for secondary analysis only. The participants recruited from a medical program called the NAGALA database received regular medical examinations and standardized questionnaires to obtain the baseline variables. Abdominal ultrasound was used to diagnose fatty liver disease. The participants were followed up, and the duration and occurrence of T2DM were documented. The GGT/HDL-C ratio evaluated at baseline served as the independent variable, while the occurrence of diabetes served as the dependent variable.

RESULTS

A total of 15,453 cases (8,419 men and 7,034 women) were included in our study. After adjusting for age, sex, BMI, DBP, SBP, ALT, AST, TG, TC, HbA1C, FPG, drinking status, smoking status, exercise status, and fatty liver, we observed that the GGT/HDL-C ratio was positively associated with the incidence of T2DM (hazard ratio = 1.005, 95% confidence interval: 1.000 to 1.010, P = 0.0667). The results were consistent when the GGT/HDL-C quartile was used as a categorical variable (P for trend < 0.00396). A curvilinear relationship with a threshold effect was identified between the GGT/HDL-C ratio and the risk of incident T2DM. On the left of the point, a one-unit increase in the GGT/HDL-C ratio was associated with a 1.5-fold increase in the risk of incident T2DM (hazard ratio 2.57, 95% confidence interval 1.20 to 5.49). On the right of the point, when GGT/HDL-C was greater than 6.53, their relationship became saturated.

CONCLUSION

The GGT/HDL-C ratio correlated with the incidence of T2DM in a curvilinear form with a threshold effect. Their positive relationship could be observed when GGT/HDL-C was less than 6.53.

Novel extraction technologies and potential applications of egg yolk proteins

The high nutritional value and diverse functional properties of egg yolk proteins have led to its widespread use in the fields of food, medicine, and cosmetics. Various extraction methods have been reported to obtain the proteins from egg yolk, however, their utilization is limited due to the relatively low extraction efficiency and/or toxic solvents involved. Several simpler and greener technologies, especially physical fields (ultrasound), have been successfully developed to improve the extraction efficiency. The egg yolk proteins may exert multiple biological activities, enabling them to be a promising tool in improve human health and wellbeing, such as anti-obesity, anti-atherosclerosis, anti-osteoporosis, diagnosis and therapy for SARS-CoV-2 infections. This article summarizes the novel extraction technologies and latest applications of the egg yolk proteins in the recent 5 years, which should stimulate their utilization as health-promoting functional ingredients in foods and other commercial products.

High-density lipoprotein-cholesterol and incident type 2 diabetes mellitus among African Americans: The Jackson Heart Study

AIMS

Accruing evidence suggests an association between high-density lipoprotein cholesterol (HDL-C) and incident diabetes. However, there is a paucity of data on the link between HDL-C and diabetes, especially among African Americans (AAs). We aimed to assess the association of HDL-C and its fractions with incident type 2 diabetes among AAs.

METHODS

We included Jackson Heart Study participants who attended visit 1 (2001-2004), were free from diabetes and were not treated with lipid-modifying medications. Incident diabetes was assessed at two subsequent-yearly visits (2 and 3). We cross-sectionally assessed the association of HDL-C and insulin resistance (IR) using multivariable linear models. We prospectively assessed the association of HDL-C and its fractions with incident diabetes using multivariable Cox regression models.

RESULTS

Among 2829 participants (mean age: 51.9 ± 12.4 years, 63.9% female), 487 participants (17%) developed new-onset diabetes, over a median follow-up of 8 years. In adjusted models, a higher HDL-C concentration was associated with a lower odds of IR (odds ratio [OR] per standard deviation [SD] increment: OR 0.56 [95% confidence interval, CI 0.50-0.63], p < 0.001). In adjusted models, a higher HDL-C concentration was associated with a lower risk of diabetes (HR per SD increment: 0.78 [95% CI 0.71, 0.87], p < 0.001; HR for highest vs. the lowest tertile of HDL-C was 0.56 [95% CI: 0.44, 0.71], p < 0.001).

CONCLUSION

In a sample of African-American adults not on any lipid-modifying therapy, high HDL-C concentrations were inversely associated with the risk of new-onset diabetes. These findings suggest a strong link between HDL-C metabolism and glucose regulation.

The Relationship Between Lipoproteins and Insulin Sensitivity in Youth With Obesity and Abnormal Glucose Tolerance

CONTEXT

Youth with obesity and abnormal glucose tolerance have an increased risk for atherosclerosis but the relative contributions of insulin resistance and hyperglycemia to dyslipidemia and the development of subclinical atherosclerosis are unknown.

OBJECTIVE

This work aims to determine the association between insulin resistance, dyslipidemia, and carotid intimal thickness (cIMT) in adolescents with normal and abnormal glucose tolerance.

METHODS

An observational cohort study in 155 youth: 44 obese insulin sensitive (OIS; fasting insulin ≤ 20 µM/mL, body mass index [BMI] ≥ 95th percentile), 35 obese insulin resistant (OIR; fasting insulin > 20 µM/mL, BMI ≥ 95th percentile), 34 obese abnormal glucose tolerant (AGT; BMI ≥ 95th percentile), and 42 Lean (BMI 5th-85th percentile). Lipids, lipoprotein particle size and concentration (-P), insulin sensitivity (SI an intravenous glucose test), and CMIT were compared using linear models adjusted for age, race/ethnicity, biological sex, and Tanner stage. Lipid/lipoprotein profile and CMIT were reevaluated in a subset after 2 years.

RESULTS

Compared to OIS and Lean, OIR and AGT had elevated triglycerides and low high-density lipoprotein cholesterol (HDL-C) but similar total cholesterol and low-density lipoprotein cholesterol (LDL-C). Among OIS, OIR, AGT, lower SI was associated with atherogenic lipids (higher triglycerides, LDL-C, non-HDL-C, and lower HDL-C) and lipoproteins (higher total LDL-P and small HDL-P, and lower large HDL-P). There was a steeper decline in the association of SI with HDL-C and large HDL-P in AGT compared with OIR and OIS. cIMT was comparable across groups and inversely correlated with SI, with no change after 2 years.

CONCLUSION

Among youth with obesity, insulin resistance was associated with an atherogenic lipoprotein/lipid profile and cIMT, regardless of glucose tolerance status. Insulin resistance in AGT youth was associated with a shift to smaller HDL-P compared to normoglycemic youth with obesity. Alterations in HDL-P metabolism may be early adverse manifestations of hyperglycemia in youth with obesity.

Gamma-glutamyl transferase to high-density lipoprotein cholesterol ratio: A valuable predictor of type 2 diabetes mellitus incidence

BACKGROUND

Gamma-glutamyl transferase (GGT) and high-density lipoprotein cholesterol (HDL-C) have been proven to be valuable predictors of type 2 diabetes mellitus (T2DM). The aim of this study was to investigate the association between GGT/HDL-C ratio and incident T2DM.

METHODS

The study retrospectively analyzed 15453 participants from 2004 to 2015. Cox proportional hazards regression models and Kaplan-Meier curves were used to elucidate the effect of GGT/HDL-C ratio on T2DM. Restricted cubic spline (RCS) analysis was performed to explore any non-linear correlation between GGT/HDL-C ratio and the risk of T2DM. The predictive performance of GGT, HDL-C and GGT/HDL-C ratio for T2DM was evaluated utilizing receiver-operating-characteristic (ROC) curves.

RESULTS

During a median follow-up of 5.39 years, 373 cases of incident T2DM were observed. Kaplan-Meier curves showed that the cumulative probabilities of T2DM increased in the participants with higher GGT/HDL-C ratio significantly (P < 0.001). Cox models further clarified that high GGT/HDL-C ratio was an independent risk factor for T2DM (HR = 1.01, 95% CI = 1.00-1.01, P = 0.011). Linear positive correlation between GGT/HDL-C ratio and the risk of T2DM was demonstrated through RCS analysis. In the ROC analysis, GGT/HDL-C ratio (AUC = 0.75, 95% CI = 0.73-0.77) showed competitive role in the prediction of T2DM compared with single GGT and HDL-C.

CONCLUSIONS

The GGT/HDL-C ratio could serve as a valuable predictor of T2DM, and the risk of T2DM increases in the condition of higher GGT/HDL-C ratio.

The value of HDL subfractions in predicting cardiovascular outcomes in untreated, diabetic patients with stable coronary artery disease: An age- and gender-matched case-control study

OBJECTIVE

The aim of the present study was to examine the value of high-density lipoprotein (HDL) subfractions for predicting cardiovascular events (CVEs) in untreated type 2 diabetes mellitus (T2DM) patients with stable coronary artery disease (SCAD) using an age- and gender-matched case-control study.

METHODS

In total, 185 SCAD patients and 185 T2DM patients with SCAD were enrolled and subjected to a clinical follow-up of CVEs. HDL subfractions were analyzed using the Quantimetrix Lipoprint System. The relationship between HDL subfractions and CVEs in T2DM patients with SCAD was evaluated by Kaplan-Meier analysis and Cox proportional hazard models.

RESULTS

During a median 37.7-month follow-up, T2DM patients with SCAD had a higher percentage of CVEs compared to SCAD patients (p=0.039). The concentration of the combined intermediate and small HDL-C subfraction (defined as the mixed HDL subfraction) was related to the event incidence in T2DM patients with SCAD (p=0.004), and it was positively associated with increased CVEs even after adjustment in three models. Kaplan-Meier curve analysis indicated that T2DM patients with SCAD in the high mixed HDL subfraction group (>28 mg/dL) had lower event-free survival rates (p=0.008).

CONCLUSIONS

Elevated concentration of the mixed HDL subfraction concentration predicts events in T2DM patients with SCAD.

Sonographic Optic Nerve Diameter and Clinical Biomarkers in Patients With Poorly Controlled Diabetes: A Comparative Analysis With Nondiabetic Subjects

Objective:

The study assessed optic nerve diameter (OND) and clinical biomarkers in patients with poorly controlled diabetes compared with healthy nondiabetic volunteers.

Materials and Methods:

There were 1320 adult participants recruited to the study. The cohort was divided into 600 Type 2 diabetic (DM II) patients and 720 apparently healthy, nondiabetic volunteers. The OND was measured using a high-resolution dedicated ultrasound device (Sonoace 5500; Medicol, Medison, Miami, FL, USA) with a 10-MHz linear array transducer. Subjects were examined in a supine position with their eyes closed. Three measurements of the OND were taken and the average recorded. Hemoglobin A1c concentration and lipid profiles were determined using Bio-Rad Diamat analyzer (Bio-Rad, Hercules, CA). Body mass index and age were matched for both cohorts for comparativeness.

Results:

The mean OND of the DM II patients was 3.10 ± 0.14 mm (range of 2.6–4.0 mm), which was significantly ( P < .05) lower than the control volunteers (4.22 ± 0.15 mm). The OND demonstrated a negative significant correlation with HA1c, duration of diabetes and low-density lipoprotein cholesterol level ( P < .05). Lipid profiles, blood urea, serum creatinine, and hemoglobin A1c showed statistical difference between diabetics and control subjects.

Conclusion:

Poorly controlled DM II patients may have significantly narrower OND than nondiabetic patients. This imaging biomarker has the potential to transform visual care for DM II patients.

HDL and type 2 diabetes: the chicken or the egg?

HDL is a complex macromolecular cluster of various components, such as apolipoproteins, enzymes and lipids. Quality evidence from clinical and epidemiological studies led to the principle that HDL-cholesterol (HDL-C) levels are inversely correlated with the risk of CHD. Nevertheless, the failure of many cholesteryl ester transfer protein inhibitors to protect against CVD casts doubts on this principle and highlights the fact that HDL functionality, as dictated by its proteome and lipidome, also plays an important role in protecting against metabolic disorders. Recent data indicate that HDL-C levels and HDL particle functionality are correlated with the pathogenesis and prognosis of type 2 diabetes mellitus, a major risk factor for CVD. Hyperglycaemia leads to reduced HDL-C levels and deteriorated HDL functionality, via various alterations in HDL particles' proteome and lipidome. In turn, reduced HDL-C levels and impaired HDL functionality impact the performance of key organs related to glucose homeostasis, such as pancreas and skeletal muscles. Interestingly, different structural alterations in HDL correlate with distinct metabolic abnormalities, as indicated by recent data evaluating the role of apolipoprotein A1 and lecithin-cholesterol acyltransferase deficiency in glucose homeostasis. While it is becoming evident that not all HDL disturbances are causatively associated with the development and progression of type 2 diabetes, a bidirectional correlation between these two conditions exists, leading to a perpetual self-feeding cycle.

HDL Particle Subspecies and Their Association With Incident Type 2 Diabetes: The PREVEND Study

CONTEXT

High-density lipoproteins (HDL) may be protective against type 2 diabetes (T2D) development, but HDL particles vary in size and function, which could lead to differential associations with incident T2D. A newly developed nuclear magnetic resonance (NMR)-derived algorithm provides concentrations for 7 HDL subspecies.

OBJECTIVE

We aimed to investigate the association of HDL particle subspecies with incident T2D in the general population.

METHODS

Among 4828 subjects of the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study without T2D at baseline, HDL subspecies with increasing size from H1P to H7P were measured by NMR (LP4 algorithm of the Vantera NMR platform).

RESULTS

A total of 265 individuals developed T2D (median follow-up of 7.3 years). In Cox regression models, HDL size and H4P (hazard ratio [HR] per 1 SD increase 0.83 [95% CI, 0.69-0.99] and 0.85 [95% CI, 0.75-0.95], respectively) were inversely associated with incident T2D, after adjustment for relevant covariates. In contrast, levels of H2P were positively associated with incident T2D (HR 1.15 [95% CI, 1.01-1.32]). In secondary analyses, associations with large HDL particles and H6P were modified by body mass index (BMI) in such a way that they were particularly associated with a lower risk of incident T2D, in subjects with BMI < 30 kg/m2.

CONCLUSION

Greater HDL size and lower levels of H4P were associated with a lower risk, whereas higher levels of H2P were associated with a higher risk of developing T2D. In addition, large HDL particles and H6P were inversely associated with T2D in nonobese subjects.

High Density Lipoproteins and Diabetes

Epidemiological studies have established that a high plasma high density lipoprotein cholesterol (HDL-C) level is associated with reduced cardiovascular risk. However, recent randomised clinical trials of interventions that increase HDL-C levels have failed to establish a causal basis for this relationship. This has led to a shift in HDL research efforts towards developing strategies that improve the cardioprotective functions of HDLs, rather than simply increasing HDL-C levels. These efforts are also leading to the discovery of novel HDL functions that are unrelated to cardiovascular disease. One of the most recently identified functions of HDLs is their potent antidiabetic properties. The antidiabetic functions of HDLs, and recent key advances in this area are the subject of this review. Given that all forms of diabetes are increasing at an alarming rate globally, there is a clear unmet need to identify and develop new approaches that will complement existing therapies and reduce disease progression as well as reverse established disease. Exploration of a potential role for HDLs and their constituent lipids and apolipoproteins in this area is clearly warranted. This review highlights focus areas that have yet to be investigated and potential strategies for exploiting the antidiabetic functions of HDLs.

Large HDL2 combined with inflammatory factors as superior predictors for coronary artery disease than small HDL3

Background

This study investigated whether combinations of high-density lipoprotein (HDL) subfractions and inflammatory markers would add value to coronary artery disease (CAD) prediction.

Methods

Non-CAD subjects (n=245) were stratified into low/moderate/high-Framingham risk (L/M/H-FR) groups and 180 CAD patients were enrolled. Levels of HDL-C, HDL₂, HDL₃, monocyte chemoattractant protein-1 (MCP-1), and high-sensitivity C-reactive protein (hsCRP) were measured. Multivariable logistic models for CAD were estimated with a single parameter or all parameters together after adjustment for conventional risk factors (CRFs), and Z statistics, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) were used to compare discrimination among different models.

Results

The results show that HDL-C, HDL_2, and HDL₃ gradually decreased, while MCP-1 and hsCRP gradually increased from L/M/H-FR to the CAD group. When applying a single factor in the CRFs-adjusted models, HDL-C (OR 0.011, 95% CI, 0.002–0.071, P<0.05) and HDL₂ (OR 0.000072, 95% CI, 0.000001–0.004, P<0.05), but not HDL₃, were significantly related to CAD risk. Only HDL₂ (OR 0.000072, 95% CI, 0.000001–0.004, P<0.001) remained significant when applying all HDL parameters. In the model including all HDL and inflammatory parameters, HDL₂ (OR 0.001, 95% CI, 0.000027–0.051), MCP-1 (OR 1.066, 95% CI, 1.039–1.094), and hsCRP (OR 1.130, 95% CI, 1.041–1.227) showed significant differences (all P<0.05). This combined model showed improved discrimination over the models with a single factor (P<0.05) or all HDL parameters (Z=3.299, NRI =0.179, IDI =0.081, P<0.001).

Conclusions

Large HDL₂ is superior to small HDL₃ in the inverse association with CAD. The combination of HDL₂, MCP-1, and hsCRP with CRFs provides an optimal prediction for CAD.

Endothelial Dysfunction in Diabetes Is Aggravated by Glycated Lipoproteins; Novel Molecular Therapies

Diabetes and its vascular complications affect an increasing number of people. This disease of epidemic proportion nowadays involves abnormalities of large and small blood vessels, all commencing with alterations of the endothelial cell (EC) functions. Cardiovascular diseases are a major cause of death and disability among diabetic patients. In diabetes, EC dysfunction (ECD) is induced by the pathological increase of glucose and by the appearance of advanced glycation end products (AGE) attached to the plasma proteins, including lipoproteins. AGE proteins interact with their specific receptors on EC plasma membrane promoting activation of signaling pathways, resulting in decreased nitric oxide bioavailability, increased intracellular oxidative and inflammatory stress, causing dysfunction and finally apoptosis of EC. Irreversibly glycated lipoproteins (AGE-Lp) were proven to have an important role in accelerating atherosclerosis in diabetes. The aim of the present review is to present up-to-date information connecting hyperglycemia, ECD and two classes of glycated Lp, glycated low-density lipoproteins and glycated high-density lipoproteins, which contribute to the aggravation of diabetes complications. We will highlight the role of dyslipidemia, oxidative and inflammatory stress and epigenetic risk factors, along with the specific mechanisms connecting them, as well as the new promising therapies to alleviate ECD in diabetes.

HDL Subclass Analysis in Predicting Metabolic Syndrome in Koreans With High HDL Cholesterol Levels

Background

High-density lipoprotein cholesterol (HDL-C) is a complex mixture of subclasses with heterogeneous atheroprotective activities. We analyzed HDL-C subclass in relation to cardiovascular risk and metabolic syndrome (MetS) in a population with high HDL-C levels.

Methods

A total of 300 Korean individuals with high HDL-C levels (≥2.331 mmol/L) were enrolled following a comprehensive general medical examination including body composition analysis. HDL3-C levels were measured using the HDL3-EX SEIKEN kit (Randox Ltd., Crumlin, UK) and non-HDL3-C levels were calculated by subtracting HDL3-C levels from total HDL-C levels.

Results

HDL3-C levels and HDL3-C proportion had a weak positive correlation with low-density lipoprotein cholesterol (LDL-C) and triglycerides (r=0.21, r=0.25; r=0.26, r=0.34, respectively, all P<0.001); in contrast, non-HDL3-C levels had a weak negative correlation with these parameters (r=−0.17 and r=−0.25, respectively, both P<0.005). HDL3-C levels and HDL3-C proportion were significantly higher in the MetS group (N=8) than in the non-MetS group (0.71 vs 0.63 mmol/L, P=0.001; 29.7 vs 25.8%, P=0.001, respectively); these were the only predictors of MetS among the lipid variables (areas under the curves [AUC]=0.84 and 0.83, respectively, both P=0.001).

Conclusions

In populations with high HDL-C levels, HDL-C subclass may provide a greater amount of information on cardiovascular risk and MetS than HDL-C levels alone.

Genetically Mediated Lipid Metabolism and Risk of Insulin Resistance: Insights from Mendelian Randomization Studies

Dysregulated lipid metabolism, characterized by higher levels of circulating triglycerides, higher levels of small, low density lipoprotein, and accumulation of intracellular lipids, is linked to insulin resistance and related complications such as type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVD). Considering that various metabolic, genetic, and environmental factors are involved in the development of T2DM and CVD, the causalities of these diseases are often confounded. In recent years, Mendelian randomization (MR) studies coupling genetic data in population studies have revealed new insights into the risk factors influencing the development of CVD and T2DM. This review briefly conceptualizes MR and summarizes the genetic traits related to lipid metabolism by evaluating their effects on the indicators of insulin resistance based on the results of recent MR studies. The data from the MR study cases referred to in this review indicate that the causal associations between lipid status and insulin resistance in MR studies are not conclusive. Furthermore, available data on Asian ethnicities, including Korean, are very limited. More genome-wide association studies and MR studies on Asian populations should be conducted to identify Asian- or Korean-specific lipid traits in the development of insulin resistance and T2DM. The present review discusses certain studies that investigated genetic variants related to nutrient intake that can modify lipid metabolism outcomes. Up-to-date inferences on the causal association between lipids and insulin resistance using MR should be interpreted with caution because of several limitations, including pleiotropic effects and lack of information on genotype and ethnicity.

Lipid Biomarkers as Predictors of Diastolic Dysfunction in Diabetes with Poor Glycemic Control

Uncontrolled type-1 diabetes (T1DM) can lead to dyslipidaemia and albuminuria, which may promote cardiovascular injuries. However, some lipidemic factors could be useful in predicting cardiac dysfunction. Seventy-eight adolescents under insulin treatment due to a 6-year history of T1DM and were retrospectively examined. Glycemia, lipidemia, and albuminuria were measured in addition to development of cardiovascular abnormalities Both girls and boys showed higher HbA1c and fasting blood glucose and 27.1% females and 33.3% males exhibited microalbuminuria though their plasma levels of total cholesterol (TC), triglycerides (TG), and low-density lipoproteins (LDL) and high-density lipoproteins (HDL lipoproteins were in the normal range. They exhibited a preserved systolic function, but 50% of females and 66.6% of males had developed diastolic failures. Interestingly, girls with diastolic dysfunction showed significantly lower concentrations of HDL and higher TC/HDL and TG/HDL ratios. In fact, low HDL levels (OR 0.93; 95% CI 0.88-0.99; p = 0.029) and high TC/HDL (OR 2.55; 95% CI 1.9-5.45; p = 0.016) and TG/HDL (OR 2.74; 95% CI 1.12-6.71; p = 0.028) ratios associated with the development of diastolic complications. The cut-off values for HDL, TC/HDL, and TG/HDL were 49 mg/dL, 3.0 and 1.85, respectively. HDL and TC/HDL and TG/HDL ratios may be useful for predicting diastolic dysfunction in girls with uncontrolled T1DM.

High-Density Lipoprotein Particles and Their Relationship to Posttransplantation Diabetes Mellitus in Renal Transplant Recipients

High concentrations of high-density lipoprotein (HDL) cholesterol are likely associated with a lower risk of posttransplantation diabetes mellitus (PTDM). However, HDL particles vary in size and density with yet unestablished associations with PTDM risk. The aim of our study was to determine the association between different HDL particles and development of PTDM in renal transplant recipients (RTRs). We included 351 stable outpatient adult RTRs without diabetes at baseline evaluation. HDL particle characteristics and size were measured by nuclear magnetic resonance (NMR) spectroscopy. During 5.2 (IQR, 4.1‒5.8) years of follow-up, 39 (11%) RTRs developed PTDM. In multivariable Cox regression analysis, levels of HDL cholesterol (hazard ratio [HR] 0.61, 95% confidence interval [CI] 0.40-0.94 per 1SD increase; p = 0.024) and of large HDL particles (HR 0.68, 95% CI 0.50-0.93 per log 1SD increase; p = 0.017), as well as larger HDL size (HR 0.58, 95% CI 0.36-0.93 per 1SD increase; p = 0.025) were inversely associated with PTDM development, independently of relevant covariates including, age, sex, body mass index, medication use, transplantation-specific parameters, blood pressure, triglycerides, and glucose. In conclusion, higher concentrations of HDL cholesterol and of large HDL particles and greater HDL size were associated with a lower risk of PTDM development in RTRs, independently of established risk factors for PTDM development.

Metabolic disorders and inflammation are associated with familial combined hyperlipemia

BACKGROUND

Familial Combined Hyperlipidemia (FCH) is related to different metabolic disorders. The objective of this study was to evaluate the presence of alterations of hydrocarbonated metabolism and lipid profile together with inflammatory and adhesion molecules in subjects with FCH compared to controls.

METHODS

75 HFC patients and 75 healthy individuals were studied. Glucose, insulin, HOMA-IR index and lipid parameters, in addition to anti-oxidized LDL antibodies (Anti ox-LDL), small and dense LDL (sdLDL) and HDL subfractions, proinflammatory cytokines and adhesion molecules were measured.

RESULTS

FCH patients showed higher levels of hydrocarbonated metabolism parameters, total cholesterol, triglycerides, LDLc, Apolipoprotein B and non-HDLc (p < .001), and lower levels of HDLc (p < .001) and Apolipoprotein AI (p < .05) than controls. In addition, the inflammatory markers hsCRP, IL-6, IL-8, P-selectin, E-selectin and ICAM were all higher with (p < .05) respect to controls. The increase of sdLDL was correlated with the presence of IR and IL-6 levels. Significant differences in diameter and percentage of phenotype B LDL, small HDL subfractions and Anti ox-LDL were also detected between patients and controls.

CONCLUSIONS

The lipid characteristics of FCH are confirmed by IR and a low grade inflammatory state in patients, and are associated with the predominance of sdLDL and Anti ox-LDL.

The Role of High-Density Lipoproteins in Diabetes and Its Vascular Complications

Almost 600 million people are predicted to have diabetes mellitus (DM) by 2035. Diabetic patients suffer from increased rates of microvascular and macrovascular complications, associated with dyslipidaemia, impaired angiogenic responses to ischaemia, accelerated atherosclerosis, and inflammation. Despite recent treatment advances, many diabetic patients remain refractory to current approaches, highlighting the need for alternative agents. There is emerging evidence that high-density lipoproteins (HDL) are able to rescue diabetes-related vascular complications through diverse mechanisms. Such protective functions of HDL, however, can be rendered dysfunctional within the pathological milieu of DM, triggering the development of vascular complications. HDL-modifying therapies remain controversial as many have had limited benefits on cardiovascular risk, although more recent trials are showing promise. This review will discuss the latest data from epidemiological, clinical, and pre-clinical studies demonstrating various roles for HDL in diabetes and its vascular complications that have the potential to facilitate its successful translation.

The role and function of HDL in patients with diabetes mellitus and the related cardiovascular risk

BACKGROUND

Diabetes mellitus (DM) is a major public health problem which prevalence is constantly raising, particularly in low- and middle-income countries. Both diabetes mellitus types (DMT1 and DMT2) are associated with high risk of developing chronic complications, such as retinopathy, nephropathy, neuropathy, endothelial dysfunction, and atherosclerosis.

METHODS

This is a review of available articles concerning HDL subfractions profile in diabetes mellitus and the related cardiovascular risk. In this review, HDL dysfunction in diabetes, the impact of HDL alterations on the risk diabetes development as well as the association between disturbed HDL particle in DM and cardiovascular risk is discussed.

RESULTS

Changes in the amount of circulation lipids, including triglycerides and LDL cholesterol as well as the HDL are frequent also in the course of DMT1 and DMT2. In normal state HDL exerts various antiatherogenic properties, including reverse cholesterol transport, antioxidative and anti-inflammatory capacities. However, it has been suggested that in pathological state HDL becomes "dysfunctional" which means that relative composition of lipids and proteins in HDL, as well as enzymatic activities associated to HDL, such as paraoxonase 1 (PON1) and lipoprotein-associated phospholipase 11 (Lp-PLA2) are altered. HDL properties are compromised in patients with diabetes mellitus (DM), due to oxidative modification and glycation of the HDL protein as well as the transformation of the HDL proteome into a proinflammatory protein. Numerous studies confirm that the ability of HDL to suppress inflammatory signals is significantly reduced in this group of patients. However, the exact underlying mechanisms remains to be unravelled in vivo.

CONCLUSIONS

The understanding of pathological mechanisms underlying HDL dysfunction may enable the development of therapies targeted at specific subpopulations and focusing at the diminishing of cardiovascular risk.