Serum apolipoproteins are associated with systemic and retinal microvascular function in people with diabetes

The Association between Diabetic Retinopathy and Macular Degeneration: A Nationwide Population-Based Study

OBJECTIVE

Age-related macular degeneration (AMD), particularly its exudative form, is a primary cause of vision impairment in older adults. As diabetes becomes increasingly prevalent in aging, it is crucial to explore the potential relationship between diabetic retinopathy (DR) and AMD. This study aimed to assess the risk of developing overall, non-exudative, and exudative AMD in individuals with DR compared to those without retinopathy (non-DR) based on a nationwide population study in Taiwan.

METHODS

A retrospective cohort study was conducted using the Taiwan National Health Insurance Database (NHIRD) (2000-2013). A total of 3413 patients were placed in the study group (DR) and 13,652 in the control group (non-DR) for analysis. Kaplan-Meier analysis and the Cox proportional hazards model were used to calculate the hazard ratios (HRs) and adjusted hazard ratios (aHRs) for the development of AMD, adjusting for confounding factors, such as age, sex, and comorbid conditions.

RESULTS

Kaplan-Meier survival analysis indicated a significantly higher cumulative incidence of AMD in the DR group compared to the non-DR group (log-rank test, p < 0.001). Adjusted analyses revealed that individuals with DR faced a greater risk of overall AMD, with an aHR of 3.50 (95% CI = 3.10-3.95). For senile (unspecified) AMD, the aHR was 3.45 (95% CI = 3.04-3.92); for non-exudative senile AMD, it was 2.92 (95% CI = 2.08-4.09); and for exudative AMD, the aHR was 3.92 (95% CI = 2.51-6.14).

CONCLUSION

DR is a significant risk factor for both overall, senile, exudative, and non-exudative AMD, even after adjusting for demographic and comorbid conditions. DR patients tend to have a higher prevalence of vascular comorbidities; however, our findings indicate that the ocular pathologies inherent to DR might have a more significant impact on the progression to AMD. Early detection and appropriate treatment of AMD is critically important among DR patients.

Serum apolipoprotein A1 and B are associated with 6-month persistent and incident diabetic macular oedema in type 2 diabetes

AIMS

To investigate the associations of baseline apolipoprotein A1 (ApoA1) and B (ApoB) levels with persistent and incident diabetic macular oedema (DMO) after 6 months of follow-up.

METHODS

This is a prospective cohort study of patients aged ≥30 years with untreated diabetic retinopathy. Examinations, fundus photography and spectral domain optical coherence tomography (SD-OCT) were assessed at baseline, 1, 3 and 6 months. Serum lipids and apolipoproteins were analysed at a pathology laboratory. DMO was confirmed using SD-OCT, classified as (1) incident DMO, (2) persistent DMO and (3) regressed DMO. Eye-specific data were used, controlling for covariates and cluster effect.

RESULTS

We recruited 53 patients but only 38 completed the study [(62 eyes), 20 eyes (32.3%) with DMO]. Higher quartile of ApoA1 was associated with lower risk of persistent/incident DMO (p for trend 0.02), while higher ApoB/A1 was associated with higher risk of persistent/incident DMO (p for trend 0.02). Every 10 mg/dL increase in ApoA1 levels was associated with lower risk of persistent/incident DMO (OR 0.69; 95% CI 0.49 to 0.92; p value 0.016), whereas every 0.2 increase in ApoB/A1 was significantly associated with higher risk of persistent/incident DMO (OR 1.4; 95% CI 1.1 to 1.9; p value 0.013) at the end of the study.

CONCLUSION

Individuals with diabetes with higher ApoA1 had lower risk of persistent/incident DMO and those with higher ApoB/A1 had higher risk of persistent/incident DMO at the end of 6 months. These suggest that serum ApoA1 and ApoB/A1 levels may be important risk factors for DMO and could be predictive of persistent/incident DMO despite anti-vascular endothelial growth factor treatment.

Aqueous Humor Apolipoprotein Concentration and Severity of Diabetic Retinopathy in Type 2 Diabetes

An imbalance of plasma apolipoproteins has been linked to diabetic retinopathy (DR); however, there is scarce information regarding their presence in the aqueous humor (AH) and their role in DR. Here, we aimed at analysing the relationship between apolipoprotein concentrations in human AH and the severity of DR. Concentrations of apolipoproteins were measured retrospectively in patients with type 2 diabetes mellitus (T2DM) without DR (n = 23), with mild to moderate nonproliferative DR (NPDR) (n = 13), and advanced NPDR/proliferative DR (PDR) (n = 14) using a multiplex immunoassay. Compared to the non-apparent DR group, the concentrations of seven apolipoproteins were elevated in advanced NPDR/PDR (Apo AI 5.8-fold, Apo AII 4.5-fold, Apo CI 3.3-fold, Apo CIII 6.8-fold, Apo D 3.3-fold, Apo E 2.4-fold, and Apo H 6.6-fold). No significant differences were observed in apolipoprotein concentrations between patients with non-apparent DR and healthy controls (n = 17). In conclusion, the AH concentrations of apolipoproteins AI, AII, CI, CIII, D, E, and H increased in advancing stages of DR, suggesting their role in the pathogenesis of DR, which deserves further examination.

Is it time to change the goals of lipid management in type 1 diabetes mellitus? Changes in apolipoprotein levels during the first year of type 1 diabetes mellitus. Prospective InLipoDiab1 study

INTRODUCTION

Apolipoprotein complement is a critical determinant of lipoprotein function and metabolism. The relation between exogenous insulin and apolipoproteins (apos) in newly diagnosed type 1 diabetes mellitus (T1DM) has not yet been studied extensively. The aim of this study was to prospectively observe the changes in serum apos AI (apo AI) and AII (apo AII) in patients with newly diagnosed T1DM and their association with the daily insulin requirement.

MATERIAL AND METHODS

Thirty-four participants of the InLipoDiab1 study aged 26 (IQR: 22-32) were enrolled in this analysis. Apolipoprotein AI and AII concentrations were assessed at diagnosis and at follow-up after 3 weeks, 6 months, and 1 year of insulin treatment. The daily dose of insulin (DDI) was calculated as the amount of short- and long-acting insulin at discharge from the hospital and at follow-up visits.

RESULTS

The changes in apo AI concentration were observed after 3 weeks of insulin treatment (p = 0.04), with the largest increase between 3 weeks and 6 months of observation (p < 0.001). Apolipoprotein AII level did not change significantly after 3 weeks, while a significant increase was observed between 3 weeks and 6 months of treatment (p < 0.001). The correlations between DDI and apo concentration were not statistically significant.

CONCLUSIONS

In the first year of T1DM, there is a significant increase in apos concentration. Due to the significant deviation of apos concentration from accepted norms, changes in the recommendations of lipid control criteria in T1DM may be considered.

Neurovascular Unit: A New Target for Treating Early Stages of Diabetic Retinopathy

The concept of diabetic retinopathy as a microvascular disease has evolved and is now considered a more complex diabetic complication in which neurovascular unit impairment plays an essential role and, therefore, can be considered as a main therapeutic target in the early stages of the disease. However, neurodegeneration is not always the apparent primary event in the natural story of diabetic retinopathy, and a phenotyping characterization is recommendable to identify those patients in whom neuroprotective treatment might be of benefit. In recent years, a myriad of treatments based on neuroprotection have been tested in experimental models, but more interestingly, there are drugs with a dual activity (neuroprotective and vasculotropic). In this review, the recent evidence concerning the therapeutic approaches targeting neurovascular unit impairment will be presented, along with a critical review of the scientific gaps and problems which remain to be overcome before our knowledge can be transferred to clinical practice.

Emerging Roles of Dyslipidemia and Hyperglycemia in Diabetic Retinopathy: Molecular Mechanisms and Clinical Perspectives

Diabetic retinopathy (DR) is a significant cause of vision loss and a research subject that is constantly being explored for new mechanisms of damage and potential therapeutic options. There are many mechanisms and pathways that provide numerous options for therapeutic interventions to halt disease progression. The purpose of the present literature review is to explore both basic science research and clinical research for proposed mechanisms of damage in diabetic retinopathy to understand the role of triglyceride and cholesterol dysmetabolism in DR progression. This review delineates mechanisms of damage secondary to triglyceride and cholesterol dysmetabolism vs. mechanisms secondary to diabetes to add clarity to the pathogenesis behind each proposed mechanism. We then analyze mechanisms utilized by both triglyceride and cholesterol dysmetabolism and diabetes to elucidate the synergistic, additive, and common mechanisms of damage in diabetic retinopathy. Gathering this research adds clarity to the role dyslipidemia has in DR and an evaluation of the current peer-reviewed basic science and clinical evidence provides a basis to discern new potential therapeutic targets.

Reverse Cholesterol Transport Pathway and Cholesterol Efflux in Diabetic Retinopathy

Cholesterol esters, synthesized from cholesterol with long-chain fatty acids, are essential components of plasma lipoproteins and cell membranes that participate in various metabolic processes in the body. Cholesterol can be excreted through the cholesterol reverse transport (RCT) pathway when excessive cholesterol is produced in the extrahepatic cells, which is regulated by the liver X receptor (LXR) and its downstream regulators ATP-binding cassette subfamily A member 1 (ABCA1) and ATP-binding cassette subfamily G member 1 (ABCG1) genes. Abnormal cholesterol metabolism is closely associated with the development of diabetic retinopathy (DR). However, the precise underlying mechanism of the RCT pathway in the pathogenesis of DR is still not fully understood. This review focused on cholesterol metabolism, with a particular emphasis on the RCT pathway and its correlation with the development of DR. Particular attention has been paid to the key regulators of the RCT pathway: LXR, ABCA1, and ABCG1 genes and their potential therapeutic targets in the management of DR.

Automatic Grading of Retinal Blood Vessel in Deep Retinal Image Diagnosis

Automatic grading of retinal blood vessels from fundus image can be a useful tool for diagnosis, planning and treatment of eye. Automatic diagnosis of retinal images for early detection of glaucoma, stroke, and blindness is emerging in intelligent health care system. The method primarily depends on various abnormal signs, such as area of hard exudates, area of blood vessels, bifurcation points, texture, and entropies. The development of an automated screening system based on vessel width, tortuosity, and vessel branching are also used for grading. However, the automated method that directly can come to a decision by taking the fundus images got less attention. Detecting eye problems based on the tortuosity of the vessel from fundus images is a complicated task for opthalmologists. So automated grading algorithm using deep learning can be most valuable for grading retinal health. The aim of this work is to develop an automatic computer aided diagnosis system to solve the problem. This work approaches to achieve an automatic grading method that is opted using Convolutional Neural Network (CNN) model. In this work we have studied the state-of-the-art machine learning algorithms and proposed an attention network which can grade retinal images. The proposed method is validated on a public dataset EIARG1, which is only publicly available dataset for such task as per our knowledge.

Serum apolipoproteins and apolipoprotein-defined lipoprotein subclasses: a hypothesis-generating prospective study of cardiovascular events in T1D

APOB, APOC3, and APOE and apolipoprotein-defined lipoprotein subclasses (ADLSs; based on qualitative apolipoprotein complement) have been associated with dyslipidemia and CVD. Our main objective was to define associations of serum apolipoproteins and ADLSs with "any CVD" and "major atherosclerotic cardiovascular events" (MACEs) in a prospective study of T1D. Serum apolipoproteins and ADLSs (14 biomarkers in total) were measured in sera (obtained between 1997 and 2000) from a subset (n = 465) of the Epidemiology of Diabetes Interventions and Complications cohort. Prospective associations of "any CVD" (myocardial infarction, stroke, confirmed angina, silent myocardial infarction, revascularization, or congestive heart failure) and MACEs (fatal or nonfatal myocardial infarction or stroke), over 5,943 and 6,180 patient-years follow-up, respectively, were investigated using Cox proportional hazards models that were unadjusted and adjusted for risk factors. During 15 years of follow-up, 50 "any CVD" events and 24 MACEs occurred. Nominally significant positive univariate associations with "any CVD" were APOB, APOC3 and its subfractions [heparin precipitate, heparin-soluble (HS)], and ADLS-defined Lp-B. In adjusted analyses, APOC3-HS remained nominally significant. Nominally significant positive univariate associations with MACEs were APOC3 and its subfractions and Lp-B:C; those with total APOC3 and APOC3-HS persisted in adjusted analyses. However, these associations did not reach significance after adjusting for multiple testing. There were no significant associations of APOA1, APOA2, APOE, or other ADLSs with either "any CVD" or MACEs. These hypothesis-generating data suggest that total serum APOC3 and APOC3 in HDL are potentially important predictive biomarkers for any CVD and MACEs in adults with T1D.

Associations between serum apolipoproteins, urinary albumin excretion rate, estimated glomerular filtration rate, and diabetic retinopathy in individuals with type 2 diabetes

The published data regarding the role of serum apolipoprotein (apo) A-I, apoB, and the apoB/A-I ratio in the risk of diabetic retinopathy remain inconsistent, and there is limited information about the effect of renal status on their associations in individuals with type 2 diabetes. The aim of this study was to investigate whether serum apoA-I, apoB, and the apoB/A-I ratio are associated with the presence of diabetic retinopathy in type 2 diabetes and to explore whether the relationships between these apolipoproteins and diabetic retinopathy are modified by urinary albumin excretion rate (UACR) and estimated glomerular filtration rate (eGFR).In total, 1215 individuals with type 2 diabetes were included in this cross-sectional study. Serum levels of apoA-I and apoB and the apoB/apoA-I ratio were measured. A logistic regression model was performed to explore associations of apolipoproteins with retinopathy.Individuals with diabetic retinopathy had significantly lower levels of serum apoA-I and higher apoB/apoA-I ratio than those without diabetic retinopathy. In the multivariable analyses, the associations between apoA-I and diabetic retinopathy and between the apoB/apoA-I ratio and diabetic retinopathy were statistically significant after adjustment for the traditional risk factors (odds ratio [OR] per standard deviation [SD] increase in the log-transformed value; 0.55, 95% confidence interval (CI); 0.32 to 0.97, P = .038; OR per SD increase in the log-transformed value; 2.83, 95% CI; 1.18 to 6.76, P = .019; respectively). Additional adjustments for UACR or eGFR removed the significant associations.In individuals with type 2 diabetes, serum apoA-I and the apoB/apoA-I ratio are associated with presence of diabetic retinopathy, which might be attributable to the correlated changes in UACR and eGFR.

Lipid-lowering medication is associated with decreased risk of diabetic retinopathy and the need for treatment in patients with type 2 diabetes: A real-world observational analysis of a health claims database

AIMS

Fenofibrate and statins reduced the need for diabetic retinopathy (DR)-related treatment in clinical trials. We aimed to determine whether use of lipid-lowering medication reduces the risk of DR and the need for treatment in patients with type 2 diabetes using a real-world health claims database.

METHODS

This was an observational analysis using a nation-wide health claims database of the Japan Medical Data Center (JMDC). Type 2 diabetes was defined according to ICD-10 codes for use of glucose-lowering medication. Use of lipid-lowering medication for at least 1 year was confirmed by the Anatomical Therapeutic Chemical Classification System. DR and diabetic macular edema (DME) were determined by ICD-10 codes. DR-related treatments were determined by health insurance claims. A propensity score for use of lipid-lowering medication was estimated, and a doubly robust estimator, using the inverse probability weighting model with regression adjustment, was obtained to determine odds ratios (OR) with 95% confidence interval (95% CI) for cumulative incidence of DR and its treatments over 3 years.

RESULTS

There were 69 070 individuals with type 2 diabetes at baseline, among whom DR developed in 5687 over a period of 3 years. Use of lipid-lowering medication was associated with decreased risk of incidence of DR (OR, 0.772; 95% CI, 0.720-0.827; P < .001). Use of lipid-lowering medication was also associated with decreased incidence of DME, any treatments for DR, laser photocoagulation and vitrectomy in patients with DR at baseline.

CONCLUSIONS

In a population of patients with type 2 diabetes with a variety of risk profiles, use of lipid-lowering medication reduced the risk of DR and thus the risks involved in treatment with laser photocoagulation and vitrectomy.

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.

Serum apolipoprotein A-1 concentrations and the prevalence of cardiovascular autonomic neuropathy in individuals with type 2 diabetes

OBJECTIVE

To evaluate the relationship between levels of serum apolipoproteins and the prevalence of cardiovascular autonomic neuropathy (CAN) in type 2 diabetes.

METHODS

In total, 3199 individuals with type 2 diabetes were investigated in a cross-sectional study. The diagnosis of CAN was made based on the results of a cardiovascular reflex test. Serum apolipoprotein A-I (apoA-I) and apolipoprotein B (apoB) levels were measured.

RESULTS

Serum apoA-1 levels were significantly low in individuals with CAN, but there was no significant association between serum apoB levels and CAN. According to the degree of cardiovascular autonomic dysfunction, the average apoA-I levels were significantly different after adjusting for other covariates (normal, 1.32 g/l, 95% confidence interval [CI] 1.30-1.35; early, 1.29 g/l, 95% CI 1.27-1.31; definite, 1.27 g/l, 95% CI 1.25-1.30; P for trend = 0.010). In the multivariable analysis, the statistically significant association between apoA-I and CAN remained after adjusting for the risk factors (odds ratio per standard deviation increase in the log-transformed value, 0.65; 95% CI, 0.43-0.97, P = 0.036). Additional adjustments for serum high-sensitivity C-reactive protein (or fibrinogen) concentrations eliminated this relationship.

CONCLUSIONS

Serum apoA-I levels are inversely associated with the prevalence of CAN in individuals with type 2 diabetes. Our data also suggest that a putatively increased risk of CAN associated with decreased apoA-I levels might be mediated by correlated increases in the levels of inflammatory markers.

Concurrent Aerobic and Resistance Training Has Anti-Inflammatory Effects and Increases Both Plasma and Leukocyte Levels of IGF-1 in Late Middle-Aged Type 2 Diabetic Patients

Type 2 diabetes (T2D) is an age-related chronic disease associated with metabolic dysregulation, chronic inflammation, and activation of peripheral blood mononuclear cells (PBMC). The aim of this study was to assess the effects of a concurrent exercise training program on inflammatory status and metabolic parameters of T2D patients. Sixteen male patients (age range 55–70) were randomly assigned to an intervention group (n = 8), which underwent a concurrent aerobic and resistance training program (3 times a week; 16 weeks), or to a control group, which followed physicians' usual diabetes care advices. Training intervention significantly improved patients' body composition, blood pressure, total cholesterol, and overall fitness level. After training, plasma levels of adipokines leptin (−33.9%) and RBP4 (−21.3%), and proinflammatory markers IL-6 (−25.3%), TNF-α (−19.8%) and MCP-1 (−15.3%) decreased, whereas anabolic hormone IGF-1 level increased (+16.4%). All improvements were significantly greater than those of control patients. Plasma proteomic profile of exercised patients showed a reduction of immunoglobulin K light chain and fibrinogen as well. Training also induced a modulation of IL-6, IGF-1, and IGFBP-3 mRNAs in the PBMCs. These findings confirm that concurrent aerobic and resistance training improves T2D-related metabolic abnormalities and has the potential to reduce the deleterious health effects of diabetes-related inflammation.

Association of Blood Glucose Control and Lipids With Diabetic Retinopathy in the Veterans Affairs Diabetes Trial (VADT)

OBJECTIVE

This study examined whether lipids modify the relationship between intensive glucose control (INT) and diabetic retinopathy (DR).

RESEARCH DESIGN AND METHODS

The incidence and progression of DR were assessed in 858 of 1,791 participants with 7-field stereoscopic fundus photographs at baseline and 5 years later.

RESULTS

Odds of DR progression were lower by ∼40% in those with baseline total cholesterol (TC) ≥200 mg/dL (P = 0.007), LDL-C ≥120 mg/dL (P < 0.02), or HDL-C ≥40 mg/dL (P < 0.007) in the INT arm versus standard glycemic treatment. Odds of DR progression were reduced by ∼40% in those who had TC ≤140 mg/dL (P ≤ 0.024), triglycerides (TG) ≤120 mg/dL (P = 0.004), or HDL-C ≥45 mg/dL (P = 0.01) at the fifth year. Odds of DR progression were lower by ∼40-50% with reductions of TC by ≥40 mg/dL (P < 0.0001), of LDL-C of ≥40 mg/dL (P < 0.004), and of TG by ≥60 mg/dL (P = 0.004) at the fifth year. Odds of DR progression increased by 80% with increases in TC of ≥20 mg/dL (P < 0.0001) and by 180% with increases in LDL-C by ≥60 mg/dL (P < 0.004). After adjusting for covariants, those with higher TC at baseline and lower TC during and at the fifth year and higher HDL-C throughout study had significantly decreased odds of DR progression in INT.

CONCLUSIONS

INT was associated with decreased odds of progression but not with onset of retinopathy in those with worse lipid levels at baseline and more improved lipid levels during the study. Higher HDL-C was consistently associated with better response to INT throughout the study.

Lipids and Diabetic Retinopathy

The relationship between lipids and the development and/or severity of diabetic retinopathy (DR) is complex. Large epidemiologic studies suggest an inconsistent and overall modest association between serum triglycerides or major cholesterol species and the severity of DR; however, certain specific lipoprotein species may have stronger associations with DR severity, suggesting a pathophysiological role for lipoproteins analogous to that seen in atherosclerosis. In this lipoprotein-mediated DR pathogenesis model, damage to the blood-retinal barrier allows extravasation of lipoprotein species, which are modified in the intraretinal environment, creating substantial local damage. Additionally, hypolipidemic therapy with statins and fibrates--particularly the latter--have been shown to modulate DR in large-scale studies. Since serum lipid profile changes do not necessarily correlate with DR modulation, the efficacy of these agents may be due to their tissue-specific changes in lipoproteins and/or their anti-inflammatory, antioxidative, antiangiogenic, and antiapoptotic functions.

The clinical implications of recent studies on the structure and function of the retinal microvasculature in diabetes

The retinal blood vessels provide the opportunity to study early structural and functional changes in the microvasculature prior to clinically significant microvascular and macrovascular complications of diabetes. Advances in digital retinal photography and computerised assessment of the retinal vasculature have provided more objective and precise measurements of retinal vascular changes. Clinic- and population-based studies have reported that these quantitatively measured retinal vascular changes (e.g. retinal arteriolar narrowing and venular widening) are associated with preclinical structural changes in other microvascular systems (e.g. infarct in the cerebral microcirculation), as well as diabetes and diabetic complications, suggesting that they are markers of early microvascular dysfunction. In addition, there are new retinal imaging techniques to further assess alterations in retinal vascular function (e.g. flicker-induced vasodilatory response, blood flow and oxygen saturation) in diabetes and complications that result from the effects of chronic hyperglycaemia, inflammation and endothelial dysfunction. In this review, we summarise the latest findings on the relationships between quantitatively measured structural and functional retinal vascular changes with diabetes and diabetic complications. We also discuss clinical implications and future research to evaluate whether detection of retinal vascular changes has additional value beyond that achieved with methods currently used to stratify the risk of diabetes and its complications.

A Novel Curvature-Based Algorithm for Automatic Grading of Retinal Blood Vessel Tortuosity

Tortuosity of retinal blood vessels is an important symptom of diabetic retinopathy or retinopathy of prematurity. In this paper, we propose an automatic image-based method for measuring single vessel and vessel network tortuosity of these vessels. Simplicity of the algorithm, low-computational burden, and an excellent matching to the clinically perceived tortuosity are the important features of the proposed algorithm. To measure tortuosity, we use curvature which is an indicator of local inflection of a curve. For curvature calculation, template disk method is a common choice and has been utilized in most of the state of the art. However, we show that this method does not possess linearity against curvature and by proposing two modifications, we improve the method. We use the basic and the modified methods to measure tortuosity on a publicly available data bank and two data banks of our own. While interpreting the results, we pursue three goals. First, to show that our algorithm is more efficient to implement than the state of the art. Second, to show that our method possesses an excellent correlation with subjective results (0.94 correlation for vessel tortuosity, 0.95 correlation for vessel network tortuosity in diabetic retinopathy, and 0.7 correlation for vessel network tortuosity in retinopathy of prematurity). Third, to show that the tortuosity perceived by an expert and curvature possess a nonlinear relation.

Diabetes mellitus and risk of age-related macular degeneration: a systematic review and meta-analysis

Age-related macular degeneration (AMD) is a major cause of severe vision loss in elderly people. Diabetes mellitus is a common endocrine disorder with serious consequences, and diabetic retinopathy (DR) is the main ophthalmic complication. DR and AMD are different diseases and we seek to explore the relationship between diabetes and AMD. MEDLINE, EMBASE, and the Cochrane Library were searched for potentially eligible studies. Studies based on longitudinal cohort, cross-sectional, and case-control associations, reporting evaluation data of diabetes as an independent factor for AMD were included. Reports of relative risks (RRs), hazard ratios (HRs), odds ratio (ORs), or evaluation data of diabetes as an independent factor for AMD were included. Review Manager and STATA were used for the meta-analysis. Twenty four articles involving 27 study populations were included for meta-analysis. In 7 cohort studies, diabetes was shown to be a risk factor for AMD (OR, 1.05; 95% CI, 1.00–1.14). Results of 9 cross-sectional studies revealed consistent association of diabetes with AMD (OR, 1.21; 95% CI, 1.00–1.45), especially for late AMD (OR, 1.48; 95% CI, 1.44–1.51). Similar association was also detected for AMD (OR, 1.29; 95% CI, 1.13–1.49) and late AMD (OR, 1.16; 95% CI, 1.11–1.21) in 11 case-control studies. The pooled ORs for risk of neovascular AMD (nAMD) were 1.10 (95% CI, 0.96–1.26), 1.48 (95% CI, 1.44–1.51), and 1.15 (95% CI, 1.11–1.21) from cohort, cross-sectional and case-control studies, respectively. No obvious divergence existed among different ethnic groups. Therefore, we find diabetes a risk factor for AMD, stronger for late AMD than earlier stages. However, most of the included studies only adjusted for age and sex; we thus cannot rule out confounding as a potential explanation for the association. More well-designed prospective cohort studies are still warranted to further examine the association.

Retinopathy in non diabetics, diabetic retinopathy and oxidative stress: a new phenotype in Central Africa?

AIM

To evaluate the rates of retinopathy without diabetes and diabetic retinopathy (DR), associated with some markers of oxidative stress, antioxidants and cardiometabolic risk factors.

METHODS

We determined the prevalence of DR in 150 type 2 diabetes mellitus (T2DM) patients, that of retinopathy in 50 non diabetics, the levels of body mass index (BMI), waist circumference (WC), blood pressure, lipids, 8-isoprostane, 8-hydroxydeoxyguanosine (8-OHdG), gamma-glutamyl transferase GT (GGT), oxidized low-density lipoprotein (OxLDL), thiobarbituric acid reacting substances (TBARS), reduced glutathione (GSH), superoxide dismutase (SOD), uric acid, creatinine, albumin, total antioxidant status (TAOS), zinc, selenium, magnesium, vitamin C, vitamin D, vitamin E, glucose, apolipoprotein B (ApoB).

RESULTS

The prevalences of DR at 53y and Rtp at 62y were 44% (n=66) and 10% (n=5), respectively. The highest levels of 8-isoprostane, 8-OHdG, TBARS, SOD, and OxLDL were in DR. The lowest levels of vitamin D, vitamin C, TAOS, and vitamin E were in DR. In the case-control study discriminant analysis, the levels of vitamin C, vitamin D, ApoB, 8-OHdG, creatinine, Zn, vitamin E, and WC distinguished significantly non-diabetics without DR (controls), T2DM patients without DR and T2DM patients with DR.

CONCLUSION

Anticipation of DR onset is significantly associated with the exageration of oxidative stress biomarkers or decrease of antioxidants in African type 2 diabetics. Prevention of oxidative stress and abdominal obesity is needed. Supplementation in vitamin C, D, and E should be recommended as complement therapies of T2DM.

Phenotypes and biomarkers of diabetic retinopathy

Diabetic retinopathy (DR) remains a major cause of blindness as the prevalence of diabetes is expected to approximately double globally between 2000 and 2030. DR progresses over time at different rates in different individuals with only a limited number developing significant vision loss due to the two major vision-threatening complications, clinically significant macular edema and proliferative retinopathy. Good metabolic control is important to prevent and delay progression, but whereas some patients escape vision loss even with poor control, others develop vision loss despite good metabolic control. Our research group has been able to identify three different DR phenotypes characterized by different dominant retinal alterations and different risks of progression to vision-threatening complications. Microaneurysm turnover has been validated as a prognostic biomarker of development of clinically significant macular edema, whereas subclinical macular edema identified by OCT and mfERG appear to be also good candidates as organ-specific biomarkers of DR. Hemoglobin A1c remains the only confirmed systemic prognostic biomarker of DR progression. The availability of biomarkers of DR progression and the identification of different phenotypes of DR with different risks for development of vision-threatening complications offers new perspectives for understanding DR and for its personalized management.

Resting heart rate is associated with nonproliferative retinopathy in normoalbuminuric type 1 diabetic patients

Previous studies have reported that retinopathy might be already present in the normoalbuminuric state in type 1 diabetic patients. The aim of this study was to evaluate the prevalence and predictors of nonproliferative retinopathy in normoalbuminuric type 1 diabetic patients. The study included 312 normoalbuminuric type 1 diabetic patients with normal renal function before any interventions with statins, angiotensin-converting enzyme inhibitors, or angiotensin II receptor blockers. Diagnosis of nonproliferative retinopathy was made by fundoscopy after pupillary dilatation. Urinary albumin excretion (UAE) rate was measured from at least two 24-hour urine samples. Nonproliferative retinopathy was present in 36% of normoalbuminuric patients. Patients with nonproliferative retinopathy were older and had longer duration of diabetes, higher hemoglobin A1c , daily insulin dose, and higher resting heart rate (RHR) (P≤.01 for all). Patients in the 4th quartile of RHR were older and had longer duration of diabetes, higher hemoglobin A1c , daily insulin dose, serum creatinine, UAE, and a significantly higher prevalence of nonproliferative retinopathy compared with subjects in the 2nd, 3rd, and 4th quartiles (P<.05). In logistic regression analysis, after adjustment for risk factors, higher RHR was significantly associated with risk of nonproliferative retinopathy in patients (P<.001), with odds ratios of 1.02 to 1.08. These data suggest that RHR is independently associated with nonproliferative retinopathy in normoalbuminuric type 1 diabetic patients.

Glycation of apoprotein A-I is associated with coronary artery plaque progression in type 2 diabetic patients

OBJECTIVE

To investigate whether glycation level of apoprotein (apo)A-I is associated with coronary artery disease (CAD) and plaque progression in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Among 375 consecutive type 2 diabetic patients undergoing quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS), 82 patients with nonsignificant stenosis (luminal diameter narrowing <30% [group I]) and 190 patients with significant CAD (luminal diameter stenosis ≥70% [group II]) were included for analysis of apoA-I glycation level and serum activity of lecithin: cholesterol acyltransferase (LCAT). The control group had 136 healthy subjects. At the 1-year follow-up, angiography and IVUS were repeated mainly in group II patients for plaque progression assessment.

RESULTS

Relative intensity of apoA-I glycation by densitometry was increased, and serum LCAT activity was decreased stepwise across groups control, I, and II. These two measurements were associated with the number of diseased coronary arteries and extent index in group II. During 1-year follow-up, QCA detected 45 patients with plaque progression in 159 subjects, and IVUS found 38 patients with plaque progression in 127 subjects. Baseline relative intensity of apoA-I glycation was significantly increased in patients with plaque progression compared with those without, with values associated with changes in QCA and IVUS measurements. Multivariable regression analysis revealed that baseline relative intensity of apoA-I glycation was an independent determinant of CAD and plaque progression in type 2 diabetic patients.

CONCLUSIONS

ApoA-I glycation level is associated with the severity of CAD and coronary artery plaque progression in type 2 diabetic patients.

Retinal vessel tortuosity measures and their applications

Structural retinal vascular characteristics, such as vessel calibers, tortuosity and bifurcation angles are increasingly quantified in an objective manner, slowly replacing subjective qualitative disease classification schemes. This paper provides an overview of the current methodologies and calculations used to compute retinal vessel tortuosity. We set out the different parameter calculations and provide an insight into the clinical applications, while critically reviewing its pitfalls and shortcomings.