Serum Levels of Apolipoproteins and Incident Type 2 Diabetes: A Prospective Cohort Study

High-Density Lipoprotein Modifications: Causes and Functional Consequences in Type 2 Diabetes Mellitus

High-density lipoprotein (HDL) is a group of small, dense, and protein-rich lipoproteins that play a role in cholesterol metabolism and various cellular processes. Decreased levels of HDL and HDL dysfunction are commonly observed in individuals with type 2 diabetes mellitus (T2DM), which is also associated with an increased risk for cardiovascular disease (CVD). Due to hyperglycemia, oxidative stress, and inflammation that develop in T2DM, HDL undergoes several post-translational modifications such as glycation, oxidation, and carbamylation, as well as other alterations in its lipid and protein composition. It is increasingly recognized that the generation of HDL modifications in T2DM seems to be the main cause of HDL dysfunction and may in turn influence the development and progression of T2DM and its related cardiovascular complications. This review provides a general introduction to HDL structure and function and summarizes the main modifications of HDL that occur in T2DM. Furthermore, the potential impact of HDL modifications on the pathogenesis of T2DM and CVD, based on the altered interactions between modified HDL and various cell types that are involved in glucose homeostasis and atherosclerotic plaque generation, will be discussed. In addition, some perspectives for future research regarding the T2DM-related HDL modifications are addressed.

Antioxidant and Anti-Inflammatory Functions of High-Density Lipoprotein in Type 1 and Type 2 Diabetes

(1) Background: high-density lipoproteins (HDLs) exhibit antioxidant and anti-inflammatory properties that play an important role in preventing the development of atherosclerotic lesions and possibly also diabetes. In turn, both type 1 diabetes (T1D) and type 2 diabetes (T2D) are susceptible to having deleterious effects on these HDL functions. The objectives of the present review are to expound upon the antioxidant and anti-inflammatory functions of HDLs in both diabetes in the setting of atherosclerotic cardiovascular diseases and discuss the contributions of these HDL functions to the onset of diabetes. (2) Methods: this narrative review is based on the literature available from the PubMed database. (3) Results: several antioxidant functions of HDLs, such as paraoxonase-1 activity, are compromised in T2D, thereby facilitating the pro-atherogenic effects of oxidized low-density lipoproteins. In addition, HDLs exhibit diminished ability to inhibit pro-inflammatory pathways in the vessels of individuals with T2D. Although the literature is less extensive, recent evidence suggests defective antiatherogenic properties of HDL particles in T1D. Lastly, substantial evidence indicates that HDLs play a role in the onset of diabetes by modulating glucose metabolism. (4) Conclusions and perspectives: impaired HDL antioxidant and anti-inflammatory functions present intriguing targets for mitigating cardiovascular risk in individuals with diabetes. Further investigations are needed to clarify the influence of glycaemic control and nephropathy on HDL functionality in patients with T1D. Furthermore, exploring the effects on HDL functionality of novel antidiabetic drugs used in the management of T2D may provide intriguing insights for future research.

Fully automated immunoassay for cholesterol uptake capacity to assess high-density lipoprotein function and cardiovascular disease risk

High-density lipoprotein (HDL) cholesterol efflux capacity (CEC), which is a conventional metric of HDL function, has been associated with coronary heart disease risk. However, the CEC assay requires cultured cells and takes several days to perform. We previously established a cell-free assay to evaluate cholesterol uptake capacity (CUC) as a novel measure of HDL functionality and demonstrated its utility in coronary risk stratification. To apply this concept clinically, we developed a rapid and sensitive assay system based on a chemiluminescent magnetic particle immunoassay. The system is fully automated, providing high reproducibility. Measurement of CUC in serum is completed within 20 min per sample without HDL isolation, a notably higher throughput than that of the conventional CEC assay. CUC decreased with myeloperoxidase-mediated oxidation of HDL or in the presence of N-ethylmaleimide, an inhibitor of lecithin: cholesterol acyltransferase (LCAT), whereas CUC was enhanced by the addition of recombinant LCAT. Furthermore, CUC correlated with CEC even after being normalized by ApoA1 concentration and was significantly associated with the requirement for revascularization due to the recurrence of coronary lesions. Therefore, our new assay system shows potential for the accurate measurement of CUC in serum and permits assessing cardiovascular health.

Associations Among Biomarkers of Inflammation, Tubular Injury and Lipid Metabolism With Gestational Diabetes Mellitus Status, Microalbuminuria and Retinopathy in the Microalbuminuria and Retinopathy in Gestational Diabetes Study

OBJECTIVES

Pregnancy may be complicated by gestational diabetes mellitus (GDM) and/or microvascular complications like albuminuria, retinopathy and pre-eclampsia. In this study we aimed to identify whether mechanistic pathways associated with microvascular complications are active in pregnant women with GDM or microvascular disease.

METHODS

Urinary albumin excretion and biomarkers of inflammation, lipoprotein metabolism and tubular injury were quantified in 355 pregnant women with and without GDM. Participants underwent fundus photography graded for retinopathy. Adjusted associations between individual biomarkers and each outcome variable of interest, including GDM status, albuminuria and retinopathy, were performed using logistic regression.

RESULTS

After adjusting for age, systolic blood pressure, body mass index and ethnicity, significant associations between GDM status and apolipoprotein A1, interleukin (IL)-6, IL-8, soluble tumour necrosis factor receptor-I and -II (sTNFR-I and -II), vascular endothelial growth factor and von Willebrand factor were observed. Increased high-sensitivity C-reactive protein (hsCRP) and sTNFR-II were associated with higher levels of albuminuria. hsCRP and previous GDM were associated with retinopathy.

CONCLUSION

Mechanistic pathways associated with microvascular complications appear to be active in pregnant women with GDM or microvascular disease.

Diagnostic circulating biomarkers to detect vision-threatening diabetic retinopathy: Potential screening tool of the future?

With the increasing prevalence of diabetes in developing and developed countries, the socio-economic burden of diabetic retinopathy (DR), the leading complication of diabetes, is growing. Diabetic retinopathy (DR) is currently one of the leading causes of blindness in working-age adults worldwide. Robust methodologies exist to detect and monitor DR; however, these rely on specialist imaging techniques and qualified practitioners. This makes detecting and monitoring DR expensive and time-consuming, which is particularly problematic in developing countries where many patients will be remote and have little contact with specialist medical centres. Diabetic retinopathy (DR) is largely asymptomatic until late in the pathology. Therefore, early identification and stratification of vision-threatening DR (VTDR) is highly desirable and will ameliorate the global impact of this disease. A simple, reliable and more cost-effective test would greatly assist in decreasing the burden of DR around the world. Here, we evaluate and review data on circulating protein biomarkers, which have been verified in the context of DR. We also discuss the challenges and developments necessary to translate these promising data into clinically useful assays, to detect VTDR, and their potential integration into simple point-of-care testing devices.

Waste Clearance in the Brain and Neuroinflammation: A Novel Perspective on Biomarker and Drug Target Discovery in Alzheimer's Disease

Alzheimer’s disease (AD) is a multifactorial disease with a heterogeneous etiology. The pathology of Alzheimer’s disease is characterized by amyloid-beta and hyperphosphorylated tau, which are necessary for disease progression. Many clinical trials on disease-modifying drugs for AD have failed to indicate their clinical benefits. Recent advances in fundamental research have indicated that neuroinflammation plays an important pathological role in AD. Damage- and pathogen-associated molecular patterns in the brain induce neuroinflammation and inflammasome activation, causing caspase-1-dependent glial and neuronal cell death. These waste products in the brain are eliminated by the glymphatic system via perivascular spaces, the blood-brain barrier, and the blood–cerebrospinal fluid barrier. Age-related vascular dysfunction is associated with an impairment of clearance and barrier functions, leading to neuroinflammation. The proteins involved in waste clearance in the brain and peripheral circulation may be potential biomarkers and drug targets in the early stages of cognitive impairment. This short review focuses on waste clearance dysfunction in AD pathobiology and discusses the improvement of waste clearance as an early intervention in prodromal AD and preclinical stages of dementia.

Adrenal Androgen Predictive Effects on Clinical and Metabolic Abnormalities of Polycystic Ovary Syndrome

OBJECTIVE

 To examine the possible effects of adrenal prohormones in the prediction of clinical and metabolic abnormalities in women with polycystic ovary syndrome (PCOS).

METHODS

 The present study enrolled 299 normal cycling non-PCOS, 156 normoandrogenemic, and 474 hyperandrogenemic women with PCOS. Baseline characteristics were compared using a chi-squared test or analysis of variance (ANOVA) as appropriate. The roles of adrenal prohormones and their ratios with total testosterone in predicting co-occurring morbidities in women PCOS were evaluated using univariate and multivariate logistic regression analyses.

RESULTS

 Adrenal hyperandrogenism per dehydroepiandrosterone sulfate (DHEAS) levels were found in 32% of women with PCOS. In non-PCOS women, dehydroepiandrosterone (DHEA) and its sulfate had no predictive role concerning clinical, anthropometric, and metabolic parameters. In PCOS women, mainly in the hyperandrogenemic group, DHEA showed to be a significant predictor against most anthropometric-metabolic index abnormalities (odds ratio [OR] = 0.36-0.97; p < 0.05), and an increase in triglycerides (TG) levels (OR = 0.76; p = 0.006). Dehydroepiandrosterone sulfate presented a few predictive effects regarding PCOS-associated disorders. In controls, DHEAS predicted against the increase in estimated average glucose (OR= 0.38; p = 0.036). In the normoandrogenic group, it predicted against elevation in the waist/hip ratio (WHR) (OR= 0.59; p = 0.042), and in hyperandrogenemic PCOS women, it predicted against abnormality in the conicity index (CI) (OR = 0.31; p = 0.028).

CONCLUSION

 Dehydroepiandrosterone was shown to be a better predictor of abnormal anthropometric and biochemical parameters in women with PCOS than DHEAS. Thus, regarding adrenal prohormones, DHEA measurement, instead of DHEAS, should be preferred in PCOS management. The effects of androgen prohormones on the prediction of PCOS abnormalities are weak.

Plasma apolipoprotein concentrations and incident diabetes in subjects with prediabetes

Background

The identification of circulating biomarkers associated with the risk of type 2 diabetes (T2D) is useful for improving the current prevention strategies in the most at-risk patients. Here, we aimed to investigate the association of plasma apolipoprotein concentrations in prediabetes subjects with the incidence of new-onset T2D during follow-up.

Methods

In the IT-DIAB prospective study, 307 participants with impaired fasting glucose levels (fasting plasma glucose [FPG]: 110–125 mg/dL) were followed yearly for 5 years. The onset of T2D was defined as a first FPG value ≥ 126 mg/dL during follow-up. Apolipoprotein (apo)A-I, A-II, A-IV, B100, C-I, C-II, C-III, C-IV, D, E, F, H, J, L1, M, and (a) plasma concentrations were determined by mass spectrometry. Correlations between apolipoproteins and metabolic parameters at baseline were assessed by Spearman’s coefficients. Kaplan–Meier curves were drawn using a ternary approach based on terciles and incident T2D. The association between plasma apolipoproteins concentrations and the incidence of T2D was determined using Cox proportional-hazards models.

Results

During a median follow-up of 5-year, 115 participants (37.5%) developed T2D. After adjustment for age, sex, body mass index, FPG, HbA_1c, and statin use, the plasma levels of apoC-I, apoC-II, apoC-III, apoE, apoF, apoH, apoJ, and apoL1 were positively associated with a high risk for T2D. After further adjustment for plasma triglycerides, only apoE (1 SD natural-log-transformed hazard ratio: 1.28 [95% confidence interval: 1.06; 1.54]; p = 0.010), apoF (1.22 [1.01; 1.48]; p = 0.037), apoJ (1.24 [1.03; 1.49]; p = 0.024), and apoL1 (1.26 [1.05; 1.52]; p = 0.014) remained significantly associated with the onset of T2D. Kaplan–Meier survival curves also showed that the lower third of plasma apoE levels (< 5.97 mg/dL) was significantly associated with a lower risk of conversion to T2D (log-rank test, p = 0.002) compared to the middle and upper thirds.

Conclusions

The plasma apoE levels are positively associated with the risk of T2D in prediabetes subjects, independently of traditional risk factors. The possible associations of apoF, apoJ, and apoL1 with T2D risk also pave the way for further investigations.

Trial registration This trial was registered at clinicaltrials.gov as NCT01218061 and NCT01432509

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01452-5.

Plasma Apolipoproteins Predicting the Occurrence and Severity of Diabetic Retinopathy in Patients With Type 2 Diabetes Mellitus

OBJECTIVE

Apolipoproteins are amphipathic molecules and the major components of plasma lipoproteins. This study aims to investigate the effects of dysregulated apolipoprotein (apo) profiles and their ratios on type 2 diabetes mellitus (T2DM) and diabetic retinopathy (DR) further to test the hypothesis that altered serum level of apolipoproteins is strong biomarkers for DR.

RESEARCH DESIGN AND METHODS

This case-control study consists of 157 patients with T2DM including DM without DR, non-proliferative DR (NPDR), and proliferative DR (PDR). Fifty-eight age- and sex-matched healthy subjects were enrolled as normal controls. Blood biochemistry profile including serum levels of glucose, glycated hemoglobin (HbA1c), lipid profile [total cholesterol (TC), Triglycerides (TG), high and low-density lipoprotein (HDL-C and LDL-C)] was estimated. Apolipoproteins (apos, A-I, A-II, B, C-II, C-III, and E) was evaluated by protein chips (Luminex technology). Apolipoprotein ratios and arteriosclerosis-associated plasma indices were calculated. The Kruskal-Wallis test, independent sample t-test or Mann-Whitney U test, and multivariate regression analysis were performed to investigate the association of serum lipid biomarkers and the DR severity.

RESULTS

Serum level of apoA-I was negatively correlated with TC-(HDL-C)/HDL-C (p < 0.001), fasting glucose (p < 0.001), HbA1c (p < 0.001), and (p<0.001), while apoE, apoC-II/apoC-III, apoA-II/apoA-I were positively correlated with above traditional biomarkers (p < 0.001). Single variable logistic analysis results showed that body mass index (BMI) (p = 0.023), DM duration (p < 0.001), apoE (p < 0.001), apoC-II/apo C-III (p < 0.001), apoE/apoC-II (p < 0.001), atherogenic index (p = 0.013), fasting glucose (p < 0.001), HbA1c (p < 0.001), LPA (p = 0.001), and LDL-C/HDL-C (p = 0.031) were risk factors for the occurrence and severity of DR. Multivariate logistic regression mode showed that apoC-II/apoC-III and apoB/non-HDL-C (p < 0.001) as well as apoE/apoC-II (p = 0.001) were the independent risk factors for the occurrence and severity of DR-apopA-I and apoA-II are protective factors for DR-after controlling for the duration of DM, HbA1c, fasting glucose, and LPA.

CONCLUSIONS

apoE, apoC-II/apoC-III, apoE/apoC-II, and apoB/non-HDL-C could be used as novel biomarkers for occurrence and severity of DR, whereas apoA-I and apoA-II resulted as protective factors for DR.

Identification of blood-based biomarkers for diagnosis and prognosis of Parkinson's disease: A systematic review of proteomics studies

Parkinson's Disease (PD), a neurodegenerative disorder, is characterised by the loss of motor function and dopamine neurons. Therapeutic avenues remain a challenge due to lack of accuracy in early diagnosis, monitoring of disease progression and limited therapeutic options. Proteomic platforms have been utilised to discover biomarkers for numerous diseases, a tool that may benefit the diagnosis and monitoring of disease progression in PD patients. Therefore, this systematic review focuses on analysing blood-based candidate biomarkers (CB) identified via proteomics platforms for PD. This study systematically reviewed articles across six databases (EMBASE, Cochrane, Ovid Medline, Scopus, Science Direct and PubMed) published between 2010 and 2020. Of the 504 articles identified, 12 controlled-PD studies were selected for further analysis. A total of 115 candidate biomarkers (CB) were identified across selected 12-controlled studies, of which 23 CB were found to be replicable in more than two cohorts. Using the PANTHER Go-Slim classification system and STRING network, the gene function and protein interactions between biomarkers were analysed. Our analysis highlights Apolipoprotein A-I (ApoA-I), which is essential in lipid metabolism, oxidative stress, and neuroprotection demonstrates high replicability across five cohorts with consistent downregulation across four cohorts. Since ApoA-I was highly replicable across blood fractions, proteomic platforms and continents, its relationship with cholesterol, statin and oxidative stress as PD biomarker, its role in the pathogenesis of PD is discussed in this paper. The present study identified ApoA-I as a potential biomarker via proteomics analysis of PD for the early diagnosis and prediction of disease progression.

Association of apolipoprotein Cs with new-onset type 2 diabetes mellitus: findings from the Chinese multi-provincial cohort study

OBJECTIVES

Apolipoprotein Cs (apoCs), especially apoC-II and apoC-III, as the components of triglyceride-rich lipoproteins, play a key role in the pathophysiology of diabetes. However, prospective studies examining direct associations between apoCs and diabetes are not reproducible. The aim of this study was to evaluate the impact of apoCs on the risk of developing diabetes in a middle-aged population, and to explore possible mediators responsible for the relationship between apoCs and diabetes.

DESIGN

Prospective cohort study.

SETTING

Community-based study carried out in Beijing.

METHODS

ApoCs were measured in 1085 participants aged 45-74 years and free of type 2 diabetes mellitus (T2DM) at baseline from the Chinese Multi-Provincial Cohort Study-Beijing Project. Multivariate logistic regression was performed to examine the association of apoCs with a 5-year risk of new-onset T2DM. The impacts of triglycerides, insulin and high-sensitivity C reactive protein (hs-CRP) on the association between apoC-III and the risk of T2DM were explored by a mediation test.

RESULTS

During the 5 years of follow-up, 97 (8.9%) participants developed T2DM. ApoC-III was significantly associated with the risk of developing T2DM after multivariable adjustment (OR=1.40; 95% CI 1.07 to 1.82). This association was mainly mediated by triglyceride levels with a significant indirect effect (OR 1.61; 95% CI 1.19 to 2.18), followed by hs-CRP and insulin.

CONCLUSIONS

Our findings demonstrated that higher serum apoC-III was independently associated with increased 5-year risk of new-onset T2DM in the Chinese population, and triglyceride plays a crucial role in mediating this relationship. More attention should be paid to preventive strategies of T2DM targeting apoC-III.

The Lipocalin Apolipoprotein D Functional Portrait: A Systematic Review

Apolipoprotein D is a chordate gene early originated in the Lipocalin protein family. Among other features, regulation of its expression in a wide variety of disease conditions in humans, as apparently unrelated as neurodegeneration or breast cancer, have called for attention on this gene. Also, its presence in different tissues, from blood to brain, and different subcellular locations, from HDL lipoparticles to the interior of lysosomes or the surface of extracellular vesicles, poses an interesting challenge in deciphering its physiological function: Is ApoD a moonlighting protein, serving different roles in different cellular compartments, tissues, or organisms? Or does it have a unique biochemical mechanism of action that accounts for such apparently diverse roles in different physiological situations? To answer these questions, we have performed a systematic review of all primary publications where ApoD properties have been investigated in chordates. We conclude that ApoD ligand binding in the Lipocalin pocket, combined with an antioxidant activity performed at the rim of the pocket are properties sufficient to explain ApoD association with different lipid-based structures, where its physiological function is better described as lipid-management than by long-range lipid-transport. Controlling the redox state of these lipid structures in particular subcellular locations or extracellular structures, ApoD is able to modulate an enormous array of apparently diverse processes in the organism, both in health and disease. The new picture emerging from these data should help to put the physiological role of ApoD in new contexts and to inspire well-focused future research.

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.

Association of apolipoproteins A1 and B with type 2 diabetes and fasting blood glucose: a cross-sectional study

BACKGROUND

Apolipoprotein (Apo) may be associated with type 2 diabetes (T2D), however, little is known whether or not serum apolipoproteins are correlated with fasting blood glucose (FBG) and the prevalence of T2D in Chinese populations. In this study, we examined the association of serum ApoA1, ApoB, and the ratio of ApoB/ApoA1 (ApoB/A1 ratio) with T2D and FBG level, and compared apolipoprotein indicators in predicting T2D in Chinese adults.

METHODS

A total of 1027 subjects were enrolled in this cross-sectional study. The association of ApoA1, ApoB, and ApoB/A1 ratio with T2D prevalence was determined using logistic regression models. Multivariate-analysis of covariance (ANCOVA) was performed for comparisons of the mean difference in FBG level.

RESULTS

We found that ApoB and ApoB/A1 ratio were positively associated with T2D prevalence and FBG, while inverse association was noted between ApoA1 and T2D prevalence as well as FBG. Stratified analyses for sex, age, body mass index (BMI), smoking, and alcohol consumption showed no significant difference for the association of ApoA1, ApoB, and ApoB/A1 ratio with the prevalence of T2D among subgroups (all p-interactions> 0.05). Nonetheless, ApoA1 poorly performed in predicting T2D as it provided an AUC value of 0.310 that was significantly lower than those observed for ApoB (AUC value: 0.631) and ApoB/A1 ratio (AUC value: 0.685). Finally, path analyses indicated that the association between ApoB and T2D was mediated by BMI.

CONCLUSIONS

This study reveals the association of serum ApoA1, ApoB, and ApoB/A1 ratio with T2D and FBG in Chinese adults, suggesting that ApoB and ApoB/A1 ratio may be early indicators for predicting T2D. Prospective investigation in large cohort is needed.

Identification of biomarker panels as predictors of severity in coronary artery disease

Matrix metalloproteinases (MMPs) are implicated in atherosclerotic plaque rupture and recondition. Specific tissue inhibitors (TIMPs) control MMP functions. Both MMPs and TIMPs are potential biomarkers of plaque instability. Elevated Apo‐CII and CIII and Apo‐E levels are recognized as cardiovascular disease risk factors. We aimed to establish the best blood biomarker panel to evaluate the coronary artery disease (CAD) severity. Plasma levels of MMP‐3 and MMP‐9, TIMP‐1 and TIMP‐2, Apo‐CII, Apo‐CIII and Apo‐E were measured in 472 patients with CAD evaluated by coronary angiography and electrocardiography, and in 285 healthy controls. MMP‐3 and MMP‐9 plasma levels in CAD patients were significantly increased (P < 0.001) compared to controls (3.54‐ and 3.81‐fold, respectively). Furthermore, these increments are modulated by CAD severity as well as for Apo‐CII and Apo‐CIII levels (P < 0.001). TIMPs levels were decreased in CAD versus controls (P < 0.001) and in inverse correlation to MMPs. Standard ROC curve approach showed the importance of panels of biomarkers, including MMP‐3, MMP‐9, TIMP‐1, TIMP‐2, Apo‐CII and Apo‐CIII, for disease aggravation diagnosis. A high area under curve (AUC) value (0.995) was reached for the association of MMP‐9, TIMP‐2 and Apo‐CIII. The unbalance between MMPs and TIMPs in vascular wall and dyslipidaemia creates favourable conditions for plaque disruption. Our study suggests that the combination of MMP‐9, TIMP‐2 and Apo‐CIII values (‘CAD aggravation panel’) characterizes the severity of CAD, that is electrophysiological state, number of involved vessels, stent disposal and type of stent.

ApoCIII: A multifaceted protein in cardiometabolic disease

ApoCIII has a well-recognized role in triglyceride-rich lipoproteins metabolism. A considerable amount of data has clearly highlighted that high levels of ApoCIII lead to hypertriglyceridemia and, thereby, may influence the risk of cardiovascular disease. However, recent findings indicate that ApoCIII might also act beyond lipid metabolism. Indeed, ApoCIII has been implicated in other physiological processes such as glucose homeostasis, monocyte adhesion, activation of inflammatory pathways, and modulation of the coagulation cascade. As the inhibition of ApoCIII is emerging as a new promising therapeutic strategy, the complete understanding of multifaceted pathophysiological role of this apoprotein may be relevant. Therefore, the purpose of this work is to review available evidences not only related to genetics and biochemistry of ApoCIII, but also highlighting the role of this apoprotein in triglyceride and glucose metabolism, in the inflammatory process and coagulation cascade as well as in cardiovascular disease.

HDL (High-Density Lipoprotein) and ApoA-1 (Apolipoprotein A-1) Potentially Modulate Pancreatic α-Cell Glucagon Secretion

OBJECTIVE

Subjects with low levels of HDL (high-density lipoprotein) and ApoA-1 (apolipoprotein A-1) have increased risk to develop type 2 diabetes. HDL levels are an independent predictor of β-cell function and positively modulate it. Type 2 diabetes is characterized by defects in both β and α-cell function, but the effect of HDL and ApoA1 on α-cell function is unknown. Approach and Results: We observed a significant negative correlation (r=-0.422, P<0.0001) between HDL levels and fasting glucagon in a cohort of 132 Italian subjects. In a multivariable regression analysis including potential confounders such as age, sex, BMI, triglycerides, total cholesterol, fasting and 2-hour postload glucose, and fasting insulin, the association between HDL and fasting glucagon remained statistically significant (β=-0.318, P=0.006). CD1 mice treated with HDL or ApoA-1 for 3 consecutive days showed a 32% (P<0.001) and 23% (P<0.05) reduction, respectively, in glucagon levels following insulin-induced hypoglycemia, compared with controls. Treatment of pancreatic αTC1 clone 6 cells with HDL or ApoA-1 for 24 hours resulted in a significant reduction of glucagon expression (P<0.04) and secretion (P<0.01) after an hypoglycemic stimulus and increased Akt (RAC-alpha serine/threonine-protein kinase) and FoxO1 (forkhead/winged helix box gene, group O-1) phosphorylation. Pretreatment with Akt inhibitor VIII, PI3K (phosphatidylinositol 3-kinase) inhibitor LY294002, and HDL receptor SCARB-1 (scavenger receptor class B type 1) inhibitor BLT-1 (block lipid transport-1) restored αTC1 cell response to low glucose levels.

CONCLUSIONS

These results support the notion that HDL and ApoA-1 modulate glucagon expression and secretion by binding their cognate receptor SCARB-1, and activating the PI3K/Akt/FoxO1 signaling cascade in an in vitro α-cell model. Overall, these results raise the hypothesis that HDL and ApoA-1 may have a role in modulating glucagon secretion.

Dyslipidemia in Pediatric Type 2 Diabetes Mellitus

PURPOSE OF REVIEW

Cardiovascular (CV) disease is a major cause of mortality in type 2 diabetes mellitus (T2D). Dyslipidemia is prevalent in children with T2D and is a known risk factor for CVD. In this review, we critically examine the epidemiology, pathophysiology, and recommendations for dyslipidemia management in pediatric T2D.

RECENT FINDINGS

Dyslipidemia is multifactorial and related to poor glycemic control, insulin resistance, inflammation, and genetic susceptibility. Current guidelines recommend lipid screening after achieving glycemic control and annually thereafter. The desired lipid goals are low-density lipoprotein cholesterol (LDL-C) < 100 mg/dL, high-density lipoprotein cholesterol (HDL-C) > 35 mg/dL, and triglycerides (TG) < 150 mg/dL. If LDL-C remains > 130 mg/dL after 6 months, statins are recommended with a treatment goal of < 100 mg/dL. If fasting TG are > 400 mg/dL or non-fasting TG are > 1000 mg/dL, fibrates are recommended. Although abnormal levels of atherogenic TG-rich lipoproteins, apolipoprotein B, and non-HDL-C are commonly present in pediatric T2D, their measurement is not currently considered in risk assessment or management.

Urinary Apolipoprotein C3 Is a Potential Biomarker for Alzheimer's Disease

INTRODUCTION

Biomarkers of Alzheimer's disease (AD) that can easily be measured in routine health checkups are desirable. Urine is a source of biomarkers that can be collected easily and noninvasively. We previously reported on the comprehensive profile of the urinary proteome of AD patients and identified proteins estimated to be significantly increased or decreased in AD patients by a label-free quantification method. The present study aimed to validate urinary levels of proteins that significantly differed between AD and control samples from our proteomics study (i.e., apolipoprotein C3 [ApoC3], insulin-like growth factor-binding protein 3 [Igfbp3], and apolipoprotein D [ApoD]).

METHODS

Enzyme-linked immunosorbent assays (ELISAs) were performed using urine samples from the same patient and control groups analyzed in the previous proteomics study (18 AD and 18 controls, set 1) and urine samples from an independent group of AD patients and controls (13 AD, 5 mild cognitive impairment [MCI], and 32 controls) from the National Center for Geriatrics and Gerontology Biobank (set 2).

RESULTS

In set 1, the crude urinary levels of ApoD, Igfbp3, and creatinine-adjusted ApoD were significantly higher in the AD group relative to the control group (p = 0.003, p = 0.002, and p = 0.019, respectively), consistent with our previous proteomics results. In set 2, however, the crude urinary levels of Igfbp3 were significantly lower in the AD+MCI group than in the control group (p = 0.028), and the levels of ApoD and ApoC3 did not differ significantly compared to the control group. Combined analysis of all samples revealed creatinine-adjusted ApoC3 levels to be significantly higher in the AD+MCI group (p = 0.015) and the AD-only group (p = 0.011) relative to the control group.

CONCLUSION

ApoC3 may be a potential biomarker for AD, as validated by ELISA. Further analysis of ApoC3 as a urinary biomarker for AD is warranted.

A high-throughput mass spectrometry-based assay for large-scale profiling of circulating human apolipoproteins

Apolipoproteins govern lipoprotein metabolism and are promising biomarkers of metabolic and cardiovascular diseases. Unlike immunoassays, MS enables the quantification and phenotyping of multiple apolipoproteins. Hence, here, we aimed to develop a LC-MS/MS assay that can simultaneously quantitate 18 human apolipoproteins [A-I, A-II, A-IV, A-V, B48, B100, C-I, C-II, C-III, C-IV, D, E, F, H, J, L1, M, and (a)] and determined apoE, apoL1, and apo(a) phenotypes in human plasma and serum samples. The plasma and serum apolipoproteins were trypsin digested through an optimized procedure and peptides were extracted and analyzed by LC-MS/MS. The method was validated according to standard guidelines in samples spiked with known peptide amounts. The LC-MS/MS results were compared with those obtained with other techniques, and reproducibility, dilution effects, and stabilities were also assessed. Peptide markers were successfully selected for targeted apolipoprotein quantification and phenotyping. After optimization, the assay was validated for linearity, lower limits of quantification, accuracy (biases: -14.8% to 12.1%), intra-assay variability [coefficients of variation (CVs): 1.5-14.2%], and inter-assay repeatability (CVs: 4.1-14.3%). Bland-Altman plots indicated no major statistically significant differences between LC-MS/MS and other techniques. The LC-MS/MS results were reproducible over five repeated experiments (CVs: 1.8-13.7%), and we identified marked differences among the plasma and serum samples. The LC-MS/MS assay developed here is rapid, requires only small sampling volumes, and incurs reasonable costs, thus making it amenable for a wide range of studies of apolipoprotein metabolism. We also highlight how this assay can be implemented in laboratories.

Association between lipids and apolipoproteins on type 2 diabetes risk; moderating effects of gender and polymorphisms; the ATTICA study

BACKGROUND AND AIMS

Type 2 diabetes mellitus (T2DM) is a condition defined by hyperglycaemia, but also often presents with dyslipidaemia and suppressed HDL cholesterol. Mendelian randomization studies have suggested a causal link between low HDL cholesterol and T2DM. However, influences of gender, polymorphisms and lifestyle, all known to influence HDL cholesterol, have not been fully explored in a prospective cohort.

METHODS AND RESULTS

In 2001-2002, a random sample of 1514 males (18-87 years old) and 1528 females (18-89 years old) were recruited in the ATTICA study. The 10-year follow-up (2011-2012) included 1485 participants. Lipids and lipoproteins levels, glucose and insulin levels were measured together with apolipoprotein A1 (apoA1) 75 G/A genotype, which is known to influence HDL-cholesterol. In total, 12.9% of the study sample developed T2DM within the 10-year follow-up period. In multivariable models, for each mg/dL increase in apoA1 levels in males, 10-year T2DM risk decreased 1.02%; while every unit increase in apoB/LDL-cholesterol ratio increased risk 4-fold. Finally, for every unit increase in triglycerides/apoA1 ratio, the risk increased 85%. HOMA-IR independently predicted T2DM 10-year incidence only for carriers of GG polymorphism (all, p < 0.05), but not in carriers of the GA polymorphism (all, p > 0.05).

CONCLUSION

ApoA1 was associated with decreased T2DM risk and TG/ApoA1 and apoB/LDL were associated with increased risk of T2DM, only in males. ApoA1 polymorphism, which is associated with lower HDL cholesterol, influenced the predictive effects of HOMA-IR on T2DM incidence, which appeared to be moderated by physical activity, suggesting potential scope for more targeted preventative strategies.

Objectives, design and main findings until 2020 from the Rotterdam Study

The Rotterdam Study is an ongoing prospective cohort study that started in 1990 in the city of Rotterdam, The Netherlands. The study aims to unravel etiology, preclinical course, natural history and potential targets for intervention for chronic diseases in mid-life and late-life. The study focuses on cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, otolaryngological, locomotor, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. Since 2016, the cohort is being expanded by persons aged 40 years and over. The findings of the Rotterdam Study have been presented in over 1700 research articles and reports. This article provides an update on the rationale and design of the study. It also presents a summary of the major findings from the preceding 3 years and outlines developments for the coming period.

Apolipoprotein J is a hepatokine regulating muscle glucose metabolism and insulin sensitivity

Crosstalk between liver and skeletal muscle is vital for glucose homeostasis. Hepatokines, liver-derived proteins that play an important role in regulating muscle metabolism, are important to this communication. Here we identify apolipoprotein J (ApoJ) as a novel hepatokine targeting muscle glucose metabolism and insulin sensitivity through a low-density lipoprotein receptor-related protein-2 (LRP2)-dependent mechanism, coupled with the insulin receptor (IR) signaling cascade. In muscle, LRP2 is necessary for insulin-dependent IR internalization, an initial trigger for insulin signaling, that is crucial in regulating downstream signaling and glucose uptake. Of physiologic significance, deletion of hepatic ApoJ or muscle LRP2 causes insulin resistance and glucose intolerance. In patients with polycystic ovary syndrome and insulin resistance, pioglitazone-induced improvement of insulin action is associated with an increase in muscle ApoJ and LRP2 expression. Thus, the ApoJ-LRP2 axis is a novel endocrine circuit that is central to the maintenance of normal glucose homeostasis and insulin sensitivity.

Hepatokines are proteins secreted by the liver that can regulate whole body metabolism. Here the authors identify apolipoprotein J as a hepatokine that regulates muscle glucose metabolism and insulin resistance through a low-density lipoprotein receptor-related protein−2 mediated mechanism in mice.

A higher glycemic response to oral glucose is associated with higher plasma apolipoprotein C3 independently of BMI in healthy twins

BACKGROUND AND AIMS

Plasma apolipoprotein C3 (ApoC3) is associated with higher plasma triglyceride and type 2 diabetes incidence. We evaluated whether body mass index (BMI) or glucose metabolism were associated with ApoC3 in healthy monozygotic (MZ) twins.

METHODS AND RESULTS

Forty-seven MZ twin-pairs (20 man, 27 women), aged 23-42 years, were divided in subgroups according to discordance or concordance for (a) BMI (within-pair difference (Δ) in BMI≥3.0 or<3.0 kg/m²), or (b) 2-h glucose iAUC, during oral glucose tolerance test (ΔGlucose iAUC ≥97.5 or<97.5 mmol × 120 minutes). Within these discordant or concordant subgroups, we tested (Wilcoxon signed-rank test) co-twin differences in ApoC3, adiposity measures, insulin-resistance and beta-cell function indices, and plasma and lipoprotein lipids. In BMI-Discordant (p = 0.92) or BMI-Concordant (p = 0.99) subgroups, ApoC3 did not differ between leaner and heavier co-twins. In the Glucose-Discordant subgroup, ApoC3 was significantly higher in twins with higher Glucose iAUC than in their co-twins with the lower Glucose iAUC (10.03 ± 0.78 vs. 8.48 ± 0.52 mg/dl; M ± SE; p = 0.032). Co-twins with higher Glucose iAUC also had higher waist circumference, body fat percentage, liver fat content, worse insulin-sensitivity and beta-cell function and higher cholesterol and triglyceride in plasma VLDL, IDL, and LDL. In Glucose-Concordant twin-pairs, no significant differences were observed in the explored variables. In all twin-pairs, ΔApoC3 correlated with Δ in lipids and glucose metabolism variables, the closest relationship being between ΔApoC3 and ΔVLDL triglyceride (r = 0.74, p < 0.0001).

CONCLUSIONS

While ApoC3 was not related to acquired differences in BMI, it associated with early dysregulation of glucose metabolism independently of obesity and genetic background.

Structure-function relationships of HDL in diabetes and coronary heart disease

High-density lipoproteins (HDL) contain hundreds of lipid species and proteins and exert many potentially vasoprotective and antidiabetogenic activities on cells. To resolve structure-function-disease relationships of HDL, we characterized HDL of 51 healthy subjects and 98 patients with diabetes (T2DM), coronary heart disease (CHD), or both for protein and lipid composition, as well as functionality in 5 cell types. The integration of 40 clinical characteristics, 34 nuclear magnetic resonance (NMR) features, 182 proteins, 227 lipid species, and 12 functional read-outs by high-dimensional statistical modeling revealed, first, that CHD and T2DM are associated with different changes of HDL in size distribution, protein and lipid composition, and function. Second, different cellular functions of HDL are weakly correlated with each other and determined by different structural components. Cholesterol efflux capacity (CEC) was no proxy of other functions. Third, 3 potentially novel determinants of HDL function were identified and validated by the use of artificially reconstituted HDL, namely the sphingadienine-based sphingomyelin SM 42:3 and glycosylphosphatidylinositol-phospholipase D1 for the ability of HDL to inhibit starvation-induced apoptosis of human aortic endothelial cells and apolipoprotein F for the ability of HDL to promote maximal respiration of brown adipocytes.

High density lipoprotein and its apolipoprotein-defined subspecies and risk of dementia

Whether HDL is associated with dementia risk is unclear. In addition to apoA1, other apolipoproteins are found in HDL, creating subspecies of HDL that may have distinct metabolic properties. We measured apoA1, apoC3, and apoJ levels in plasma and apoA1 levels in HDL that contains or lacks apoE, apoJ, or apoC3 using a modified sandwich ELISA in a case-cohort study nested within the Ginkgo Evaluation of Memory Study. We included 995 randomly selected participants and 521 participants who developed dementia during a mean of 5.1 years of follow-up. The level of total apoA1 was not significantly related to dementia risk, regardless of the coexistence of apoC3, apoJ, or apoE. Higher levels of total plasma apoC3 were associated with better cognitive function at baseline (difference in Modified Mini-Mental State Examination scores tertile 3 vs. tertile 1: 0.60; 95% CI: 0.23, 0.98) and a lower dementia risk (adjusted hazard ratio tertile 3 vs. tertile 1: 0.73; 95% CI: 0.55, 0.96). Plasma concentrations of apoA1 in HDL and its apolipoprotein-defined subspecies were not associated with cognitive function at baseline or with the risk of dementia during follow-up. Similar studies in other populations are required to better understand the association between apoC3 and Alzheimer's disease pathology.

Protein Glycation: An Old Villain is Shedding Secrets

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The glycation of proteins is non-physiological post-translational incorporation of carbohydrates onto the free amines or guanidines of proteins and some lipids. Although the existence of glycated proteins has been known for forty years, a full understanding of their pathogenic nature has been slow in accruing. In recent years, however, glycation has gained widespread acceptance as a contributing factor in numerous metabolic, autoimmune, and neurological disorders, tying together several confounding aspects of disease etiology. From diabetes, arthritis, and lupus, to multiple sclerosis, amyotrophic lateral sclerosis, Alzheimer’s, and Parkinson’s diseases, an emerging glycation/inflammation paradigm now offers significant new insight into a physiologically important toxicological phenomenon. It exposes novel drug targets and treatment options, and may even lay foundations for long-awaited breakthroughs.

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This ‘current frontier’ article briefly profiles current knowledge regarding the underlying causes of glycation, the structural biology implications of such modifications, and their pathological consequences. Although several emerging therapeutic strategies for addressing glycation pathologies are introduced, the primary purpose of this mini-review is to raise awareness of the challenges and opportunities inherent in this emerging new medicinal target area.

Apolipoprotein CIII and diabetes. Is there a link?

Apolipoprotein CIII (ApoCIII), a small protein that resides on the surface of lipoprotein particles, is a key regulator of triglyceride metabolism. The inhibition of lipoprotein lipase (LPL), the increased assembly and secretion of very low-density lipoproteins (VLDL) and the decreased reuptake of triglyceride-rich lipoproteins (TRLs) by the liver are mechanisms associating elevated serum ApoCIII levels and hypertriglyceridemia. ApoCIII concentration is high in individuals with diabetes mellitus, indicating a possible positive correlation with impairment of glucose metabolism. The aim of this review (based on a Pubmed search until August 2018) is to present the possible mechanisms linking ApoCIII and deterioration of carbohydrate homeostasis. ApoCIII enhances pancreatic β-cells apoptosis via an increase of the cytoplasmic Ca²⁺ levels in the insulin-producing cells. In addition, overexpression of ApoCIII enhances non-alcoholic fatty liver disease and exacerbates inflammatory pathways in skeletal muscles, affecting insulin signalling and thereby inducing insulin resistance. Moreover, recent studies reveal a possible mechanism of body weight increase and glucose production through a potential ApoCIII-induced LPL inhibition in the hypothalamus. Also, the presence of ApoCIII on the surface of high-density lipoprotein particles is associated with impairment of their antiglycemic and atheroprotective properties. Modulating ApoCIII may be a potent therapeutic approach to manage hypertriglyceridemia and improve carbohydrate metabolism.

Protein markers and risk of type 2 diabetes and prediabetes: a targeted proteomics approach in the KORA F4/FF4 study

The objective of the present study was to identify proteins that contribute to pathophysiology and allow prediction of incident type 2 diabetes or incident prediabetes. We quantified 14 candidate proteins using targeted mass spectrometry in plasma samples of the prospective, population-based German KORA F4/FF4 study (6.5-year follow-up). 892 participants aged 42–81 years were selected using a case-cohort design, including 123 persons with incident type 2 diabetes and 255 persons with incident WHO-defined prediabetes. Prospective associations between protein levels and diabetes, prediabetes as well as continuous fasting and 2 h glucose, fasting insulin and insulin resistance were investigated using regression models adjusted for established risk factors. The best predictive panel of proteins on top of a non-invasive risk factor model or on top of HbA1c, age, and sex was selected. Mannan-binding lectin serine peptidase (MASP) levels were positively associated with both incident type 2 diabetes and prediabetes. Adiponectin was inversely associated with incident type 2 diabetes. MASP, adiponectin, apolipoprotein A-IV, apolipoprotein C-II, C-reactive protein, and glycosylphosphatidylinositol specific phospholipase D1 were associated with individual continuous outcomes. The combination of MASP, apolipoprotein E (apoE) and adiponectin improved diabetes prediction on top of both reference models, while prediabetes prediction was improved by MASP plus CRP on top of the HbA1c model. In conclusion, our mass spectrometric approach revealed a novel association of MASP with incident type 2 diabetes and incident prediabetes. In combination, MASP, adiponectin and apoE improved type 2 diabetes prediction beyond non-invasive risk factors or HbA1c, age and sex.

Relationship between serum apolipoproteins levels and retinopathy risk in subjects with type 2 diabetes mellitus

AIMS

Prognostic significance of apolipoproteins in diabetic retinopathy risk has not been well investigated. The aim of this study was to reveal the relationship between the risk of diabetic retinopathy and the levels of several apolipoproteins and their ratios in a 10-year prospective cohort.

METHODS

A total of 1023 diabetic patients without retinopathy were selected from a 10-year hospital-based diabetic cohort. In this cohort, all subjects had type 2 diabetes. Blood samples were obtained, and serum levels of several apolipoproteins were measured. In the follow-up period, diabetic retinopathy was diagnosed by two ophthalmologists through a series of ophthalmologic examinations. A Cox proportional hazard analysis was adopted to determine the relationship between the risk of diabetic retinopathy and the levels of several apolipoproteins and their ratios.

RESULTS

In the follow-up period, 315 diabetic patients were suffered from diabetic retinopathy, and the remaining 708 patients did not. Baseline serum level of apoAI ≥ 7.4 μmol/L was related to the decreased risk of diabetic retinopathy (HR 0.86, 95% CI 0.70-0.99). Baseline levels of apoCIII ≥ 6.3 μmol/L, apoE ≥ 1.1 μmol/L, apoCIII-to-apoAI ratio ≥ 0.9 and apoE-to-apoAI ratio ≥ 0.2 were associated with the increased risk of this complication (HR 1.25, 95% CI 1.04-1.49; HR 1.23, 95% CI 1.03-1.47; HR 1.34, 95% CI 1.11-1.60; HR 1.21, 95% CI 1.01-1.46).

CONCLUSION

Elevated level of apoAI might be a protective factor for diabetic retinopathy. Increased levels of apoCIII, apoE, apoCIII-to-apoAI and apoE-to-apoAI ratios might be risk factors for this complication.

The Rotterdam Study: 2018 update on objectives, design and main results

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, otolaryngological, locomotor, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. Since 2016, the cohort is being expanded by persons aged 40 years and over. The findings of the Rotterdam Study have been presented in over 1500 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

The impact of triglycerides on glucose tolerance: Lipotoxicity revisited

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

Association of apolipoprotein-CIII (apoC-III), endothelium-dependent vasodilation and peripheral neuropathy in a multi-ethnic population with type 2 diabetes

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a common complication of Type 2 diabetes (T2D). Apart from hyperglycemia, its pathogenesis is poorly understood. Apolipoprotein-CIII (apoC-III) associated with triglyceride metabolism, is a risk factor for cardiovascular disease. Its role in DPN is not well-established. We studied the associations of apoC-III, endothelial function and DPN.

METHODS

In patients with T2D, anthropometric data, fasting blood, and urine were collected for biochemistry and urine albumin/creatinine measurements (uACR). Endothelial function assessments were performed by laser Doppler flowmetry/imaging. DPN was considered present if there was an abnormal finding in monofilament (≤8 of 10 points) or neurothesiometer testing≥25V on either foot. Plasma apoC-III was assessed by ELISA.

RESULTS

Monofilament and neurothesiometer readings were measured in 1981 patients, mean age 57.4±10.8 years old. DPN prevalence was 10.8% (n=214). Patients with DPN compared to those without, were significantly older (p<0.0001), with longer duration of T2D (p<0.0001), had higher BMI (p=0.006), higher glucose (p=0.015) and HbA1c (p<0.0001), Systolic blood pressure (SBP) (p<0.0001), lower eGFR (p<0.0001), higher urine ACR (p<0.0001), poorer endothelium-dependent and endothelium-independent vasodilation (both p<0.0001), higher VCAM-1 (p<0.0001) and higher apoC-III [285.3 (195.2-405.6) vs 242.9(165.0-344.0) μg/ml]. After adjustment, log transformed apoC-III, remained independently associated with the presence of DPN (B=0.965, SE=0.397, p=0.015).

CONCLUSION

Plasma apoC-III is higher in patients with DPN. Apart from its known association with lipids and macrovascular complications, this study suggests its association with DPN. Whether regulating apoC-III metabolism may be an important new therapeutic approach to managing dyslipidemia and microvascular complications in T2D remains to be proven in future mechanistic and clinical studies.