Longitudinal studies of incidence and progression of diabetic retinopathy assessed by retinal photography in pima indians

Scoring and validation of a simple model for predicting diabetic retinopathy in patients with type 2 diabetes based on a meta-analysis approach of 21 cohorts

AIM

To develop and validate a model for predicting diabetic retinopathy (DR) in patients with type 2 diabetes.

METHODS

All risk factors with statistical significance in the DR prediction model were scored by their weights. Model performance was evaluated by the area under the receiver operating characteristic (ROC) curve, Kaplan-Meier curve, calibration curve and decision curve analysis. The prediction model was externally validated using a validation cohort from a Chinese hospital.

RESULTS

In this meta-analysis, 21 cohorts involving 184,737 patients with type 2 diabetes were examined. Sex, smoking, diabetes mellitus (DM) duration, albuminuria, glycated haemoglobin (HbA1c), systolic blood pressure (SBP) and TG were identified to be statistically significant. Thus, they were all included in the model and scored according to their weights (maximum score: 35.0). The model was validated using an external cohort with median follow-up time of 32 months. At a critical value of 16.0, the AUC value, sensitivity and specificity of the validation cohort are 0.772 ((95% confidence interval (95%CI): 0.740-0.803), p < .01), 0.715 and 0.775, respectively. The calibration curve lied close to the ideal diagonal line. Furthermore, the decision curve analysis demonstrated that the model had notably higher net benefits. The external validation results proved the reliability of the risk prediction model.

CONCLUSIONS

The simple DR prediction model developed has good overall calibration and discrimination performance. It can be used as a simple tool to detect patients at high risk of DR.

Effects of the ABCC8 R1420H loss-of-function variant on beta-cell function, diabetes incidence, and retinopathy

INTRODUCTION

The ABCC8 gene regulates insulin secretion and plays a critical role in glucose homeostasis. The effects of an ABCC8 R1420H loss-of-function variant on beta-cell function, incidence of type 2 diabetes, and age-at-onset, prevalence, and progression of diabetes complications were assessed in a longitudinal study in American Indians.

RESEARCH DESIGN AND METHODS

We analyzed beta-cell function through the relationship between insulin secretion and insulin sensitivity in members of this population without diabetes aged ≥5 years using standard major axis regression. We used hierarchical logistic regression models to study cross-sectional associations with diabetes complications including increased albuminuria (albumin-to-creatinine ratio (ACR) ≥30 mg/g), severe albuminuria (ACR ≥300 mg/g), reduced estimated glomerular filtration rate (eGFR <60 mL/min/1.73 m2), and retinopathy. This study included 7675 individuals (254 variant carriers) previously genotyped for the R1420H with available phenotypic data and with a median follow-up time of 13.5 years (IQR 4.5-26.8).

RESULTS

Variant carriers had worse beta-cell function than non-carriers (p=0.0004; on average estimated secretion was 22% lower, in carriers), in children and adults, with no difference in insulin sensitivity (p=0.50). At any body mass index and age before 35 years, carriers had higher type 2 diabetes incidence. This variant did not associate with prevalence of increased albuminuria (OR 0.87, 95% CI 0.66 to 1.16), severe albuminuria (OR 0.96, 95% CI 0.55 to 1.68), or reduced eGFR (OR 0.44, 95% CI 0.18 to 1.06). By contrast, the variant significantly associated with higher retinopathy prevalence (OR 1.74, 95% CI 1.19 to 2.53) and this association was only partially mediated (<11%) by glycemia, duration of diabetes, risk factors of retinopathy, or insulin use. Retinopathy prevalence in carriers was higher regardless of diabetes presence.

CONCLUSIONS

The ABCC8 R1420H variant is associated with increased risks of diabetes and of retinopathy, which may be partially explained by higher glycemia levels and worse beta-cell function.

Glycemic Measures in Childhood as Predictors of Future Diabetes-Related Microvascular Complications in an Indigenous American Population

OBJECTIVE

To examine the role of glycemic measures performed during childhood in predicting future diabetes-related nephropathy and retinopathy in a high-risk indigenous American cohort.

RESEARCH DESIGN AND METHODS

We studied associations between glycated hemoglobin (HbA1c) and 2-h plasma glucose (PG), measured during childhood (age 5 to <20 years) in a longitudinal observational study of diabetes and its complications (1965-2007), and future albuminuria (albumin creatinine ratio [ACR] ≥30 mg/g), severe albuminuria (ACR ≥300 mg/g), and retinopathy (at least one microaneurysm or hemorrhage or proliferative retinopathy on direct ophthalmoscopy). Areas under the receiver operating characteristic curve (AUCs) for childhood glycemic measures when predicting nephropathy and retinopathy were compared.

RESULTS

Higher baseline levels of HbA1c and 2-h PG significantly increased the risk of future severe albuminuria (HbA1c: hazard ratio [HR] 1.45 per %; 95% CI 1.02-2.05 and 2-h PG: HR 1.21 per mmol/L; 95% CI 1.16-1.27). When categorized by baseline HbA1c, children with prediabetes had a higher incidence of albuminuria (29.7 cases per 1,000 person-years [PY]), severe albuminuria (3.8 cases per 1,000 PY), and retinopathy (7.1 cases per 1,000 PY) than children with normal HbA1c levels (23.8, 2.4, and 1.7 cases per 1,000 PY, respectively); children with diabetes at baseline had the highest incidence of the three complications. No significant differences were observed between AUCs for models with HbA1c, 2-h PG, and fasting PG when predicting albuminuria, severe albuminuria, or retinopathy.

CONCLUSIONS

In this study, higher glycemia levels ascertained by HbA1c and 2-h PG during childhood were associated with future microvascular complications; this demonstrates the potential utility of screening tests performed in high-risk children in predicting long-term health outcomes.

What is the impact of microvascular complications of diabetes on severe COVID-19?

Evidence suggests severe coronavirus disease-19 (COVID-19) infection is characterised by pulmonary and systemic microvasculature dysfunction, specifically, acute endothelial injury, hypercoagulation and increased capillary permeability. Diabetes, which is also characterised by vascular injury in itself, confers an increased risk of adverse COVID-19 outcomes. It has been suggested that pre-existing endothelial dysfunction and microvascular disease in diabetes will exacerbate the vascular insults associated with COVID-19 and thus lead to increased severity of COVID-19 infection. In this article, we evaluate the current evidence exploring the impact of microvascular complications, in the form of diabetic retinopathy and nephropathy, in individuals with COVID-19 and diabetes. Future insights gained from exploring the microvascular injury patterns and clinical outcomes may come to influence care delivery algorithms for either of these conditions.

Progression of Diabetic Retinopathy and Declining Renal Function in Patients with Type 2 Diabetes

BACKGROUND

At a university hospital in Korea, we conducted a retrospective study to determine the association of the progression of diabetic retinopathy (DR) with declining renal function in type 2 diabetes.

METHODS

We included a total of 1527 patients with type 2 diabetes who followed up in our diabetes clinic and underwent fundus photographic examinations from August 2006 to February 2014. DR was assessed by retinal ophthalmologists using comprehensive ophthalmologic examinations.

RESULTS

The baseline prevalence of nonproliferative DR (NPDR) and proliferative DR (PDR) was 26.5% and 14.7%, respectively. Among 1303 patients with no DR and NPDR, 134 (10.3%) patients progressed to NPDR or PDR. The progression group had longer duration of diabetes, higher fasting plasma glucose, higher HbA1c, and a higher rate of ≥20% decline in eGFR during the follow-up period. After multivariate analysis, ≥20% decline in eGFR (odds ratio 2.553, 95% CI 1.219-5.348, p = 0.013) was an independent risk factor for progression of DR in patients with NPDR.

CONCLUSION

Declining renal function was independently associated with DR progression in patients with NPDR, suggesting that investigation of DR status should be recommended for patients with declining renal function.

Increased Expression of Ecto-NOX Disulfide-thiol Exchanger 1 (ENOX1) in Diabetic Mice Retina and its Involvement in Diabetic Retinopathy Development

BACKGROUND/AIM

Diabetic retinopathy (DR) is a type of retinal damage caused by a complication of diabetes and is a major cause of blindness in working-age adults. Ecto-NOX disulfide-thiol exchanger 1 (ENOX1) is a member of the ecto-NOX family involved in the plasma membrane electron transport pathway. This study aimed to investigate the role of ENOX1 in the development of DR.

MATERIALS AND METHODS

Human retinal endothelial cells (HRECs) and human retinal pigment epithelial cells (HREpiCs) exposed to a high concentration (25 mM) of D-glucose and type 2 diabetes (T2D) mice (+Lepr^db/+Lepr^db, db/db) with retinopathy were used as models to determine the ENOX1 expression levels there.

RESULTS

Our results showed that ENOX1 expression levels did not significantly change in both HRECs and HREpiCs under hyperglycemic conditions for 48 h. Nevertheless, ENOX1 expression increased significantly in T2D mouse retinas, particularly in the photoreceptor layer, compared to the control mouse retinas.

CONCLUSION

Different retinal ENOX1 expression in T2D mice and control mice suggested that ENOX1 may be involved in DR development.

Self-reported eye diseases among American Indian individuals with type 2 diabetes from the northern Midwest

PURPOSE

To determine the prevalence of eye diseases and utilization of dilated eye exams among a sample of American Indian (AI) individuals with type 2 diabetes.

METHODS

AI adults with type 2 diabetes utilizing health care at two reservation clinics were randomly sampled and recruited for interviewer-assisted paper surveys. The prevalence of eye diseases was compared across gender, age, income, and educational attainment.

RESULTS

The prevalence of retinopathy, cataracts, macular degeneration, and glaucoma were 9.4%, 26.7%, 5.2%, and 10.6% respectively, and 59.2% reported past year dilated eye exams. Older participants were more likely to report cataracts (p < 0.001) and glaucoma (p = .003). Those with lower income were more likely to report cataracts (p = 0.001).

CONCLUSIONS

Rates of self-reported eye diseases in this sample were higher, and dilated eye exams lower than other samples of the general United States population with diabetes, suggesting improvement can be made to improve the provision of care for AI individuals with type 2 diabetes.

Loss of Response Gene to Complement 32 (RGC-32) in Diabetic Mouse Retina Is Involved in Retinopathy Development

Diabetic retinopathy (DR) is a severe and recurrent microvascular complication in diabetes. The multifunctional response gene to complement 32 (RGC-32) is involved in the regulation of cell cycle, proliferation, and apoptosis. To investigate the role of RGC-32 in the development of DR, we used human retinal microvascular endothelial cells under high-glucose conditions and type 2 diabetes (T2D) mice (+Lepr^db/ + Lepr^db, db/db). The results showed that RGC-32 expression increased moderately in human retinal endothelial cells under hyperglycemic conditions. Histopathology and RGC-32 expression showed no significant changes between T2D and control mice retina at 16 and 24 weeks of age. However, RGC-32 expression was significantly decreased in T2D mouse retina compared to the control group at 32 weeks of age, which develop features of the early clinical stages of DR, namely reduced retinal thickness and increased ganglion cell death. Moreover, immunohistochemistry showed that RGC-32 was predominantly expressed in the photoreceptor inner segments of control mice, while the expression was dramatically lowered in the T2D retinas. Furthermore, we found that the level of anti-apoptotic protein Bcl-2 was decreased (approximately 2-fold) with a concomitant increase in cleaved caspase-3 (approximately 3-fold) in T2D retina compared to control. In summary, RGC-32 may lose its expression in T2D retina with features of DR, suggesting that it plays a critical role in DR pathogenesis.

One-Hour Plasma Glucose Compared With Two-Hour Plasma Glucose in Relation to Diabetic Retinopathy in American Indians

OBJECTIVE

We compared the ability of 1- and 2-h plasma glucose concentrations (1h-PG and 2h-PG, respectively), derived from a 75-g oral glucose tolerance test (OGTT), to predict retinopathy. 1h-PG and 2h-PG concentrations, measured in a longitudinal study of an American Indian community in the southwestern U.S., a population at high risk for type 2 diabetes, were analyzed to assess the usefulness of the 1h-PG to identify risk of diabetic retinopathy (DR).

RESEARCH DESIGN AND METHODS

Cross-sectional (n = 2,895) and longitudinal (n = 1,703) cohorts were assessed for the prevalence and incidence of DR, respectively, in relation to deciles of 1h-PG and 2h-PG concentrations. Areas under the receiver operating characteristic (ROC) curves for 1h-PG and 2h-PG were compared with regard to predicting DR, as assessed by direct ophthalmoscopy.

RESULTS

Prevalence and incidence of DR, based on direct ophthalmoscopy, changed in a similar manner across the distributions of 1h-PG and 2h-PG concentrations. ROC analysis showed that 1h-PG and 2h-PG were of similar value in identifying prevalent and incident DR using direct ophthalmoscopy. 1h-PG cut points of 230 and 173 mg/dL were comparable to 2h-PG cut points of 200 mg/dL (type 2 diabetes) and 140 mg/dL (impaired glucose tolerance), respectively.

CONCLUSIONS

1h-PG is a useful predictor of retinopathy risk, has a predictive value similar to that of 2h-PG, and may be considered as an alternative glucose time point during an OGTT.

High levels of circulating endothelial progenitor cells in patients with diabetic retinopathy are positively associated with ARHGAP22 expression

Diabetic retinopathy (DR) is a common microvascular complication of diabetes. Circulating endothelial progenitor cells (EPCs) are derived from bone marrow and are characterized by pathological retinal neovascularization. Rho GTPase Activating Protein 22 (ARHGAP22) is a DR susceptibility gene that interacts with its downstream regulatory protein ras-related C3 botulinum toxin substrate 1 (Rac1), to assist in endothelial cell angiogenesis and increasing capillary permeability. The aim of this study was to elucidate the relationship between ARHGAP22 expression and EPC levels in type 2 diabetes (T2D) patients with DR. Fifty T2D patients with DR were recruited. Circulating EPCs were characterized as CD31⁺/vascular endothelial growth factor-2⁺/CD45^dim/CD133⁺ and were quantified using triple staining flow cytometry. Real-time polymerase chain reaction tests were used to quantify ARHGAP22 expression. We found that T2D patients with proliferative DR had significantly lower EPC levels than those with non-proliferative DR (P = 0.028). T2D patients with EPC levels above the median value (> 4 cells/10⁵ events) had higher levels of ARHGAP22 expression (P = 0.002). EPC levels were positively correlated with ARHGAP22 expression (r = 0.364, P = 0.009). Among T2D patients with DR, a higher expression of ARHGAP22 was associated with higher levels of EPCs. ARHGAP22 may be involved in the mobilization or active circulation of EPCs, thus contributing to neovascularization during DR development.

Circulating Biomarkers of Diabetic Retinopathy: An Overview Based on Physiopathology

Diabetic retinopathy (DR) is the main cause of working-age adult-onset blindness. The currently available treatments for DR are applicable only at advanced stages of the disease and are associated with significant adverse effects. In early stages of DR the only therapeutic strategy that physicians can offer is a tight control of the risk factors for DR. Therefore, new pharmacological treatments for these early stages of the disease are required. In order to develop therapeutic strategies for early stages of DR new diagnostic tools are urgently needed. In this regard, circulating biomarkers could be useful to detect early disease, to identify those diabetic patients most prone to progressive worsening who ought to be followed up more often and who could obtain the most benefit from these therapies, and to monitor the effectiveness of new drugs for DR before more advanced DR stages have been reached. Research of biomarkers for DR has been mainly based on the pathogenic mechanism involved in the development of DR (i.e., AGEs, oxidative stress, endothelial dysfunction, inflammation, and proangiogenic factors). This review focuses on circulating biomarkers at both early and advanced stages that could be relevant for the prediction or detection of DR.

Changes in retinal microvascular diameter in patients with diabetes

BACKGROUND AND OBJECTIVES

Diabetic retinopathy is the main microvascular complication in diabetes mellitus and needs to be diagnosed early to prevent severe sight-threatening retinopathy. The purpose of this study was to quantify the retinal microvasculature pattern and analyze the influence of blood glucose level and the duration of diabetes mellitus on the retinal microvasculature.

METHODS

Two groups were analyzed: patients with diabetes (N=26) and patients without diabetes, ie, controls (N=26). A quantitative semiautomated method analyzed retinal microvasculature. The diameters of arterioles and venules were measured. The total numbers of arterioles and venules were counted. The ratio of arteriole diameter to venule diameter was calculated. The retinal microvasculature pattern was related to clinical and biochemical parameters.

RESULTS

Patients with diabetes exhibited larger venule diameters in the upper temporal quadrant of the retina compared to the lower temporal quadrant (124.85±38.03 µm vs 102.92±15.69 µm; P<0.01). Patients with diabetes for 5 or more years had larger venule diameters in the upper temporal quadrant than patients without diabetes (141.62±44.44 vs 112.58±32.11 µm; P<0.05). The degree of venodilation in the upper temporal quadrant was positively correlated with blood glucose level and the estimated duration of diabetes mellitus.

INTERPRETATION AND CONCLUSION

The employed quantitative method demonstrated that patients with diabetes exhibited venule dilation in the upper temporal quadrant, and the duration of diabetes mellitus was positively correlated with blood glucose level. Therefore, the early assessment of retinal microvascular changes is possible prior to the onset of diabetic retinopathy.

Risk factors associated with diabetic retinopathy among type 2 diabetes patients at teaching hospital in Malaysia

BACKGROUND

Diabetic retinopathy (DR) is the leading cause of blindness in the United States and it is the leading cause of new cases of blindness in adults aged 20-74. It is estimated that about 20% of patients with type 2 DM have evidence of diabetic retinopathy at diagnosis with diabetes.

OBJECTIVE

To evaluate the prevalence of DR and to determine risk factors related to diabetic retinopathy among type 2 diabetes patients attending endocrinology clinics at Hospital Universiti Sains Malaysia (HUSM).

SUBJECTS AND METHODS

The study design was observational prospective longitudinal follow-up study, the study was conducted with sample of 1077 type 2 diabetes mellitus outpatient recruited via attended the diabetes clinics at HUSM. Diagnosis of retinopathy is based on finding the diagnostic signs of retinopathy on eye exams by fundoscopy. Logistic regression analysis was used to assess the independent variables that affect the development of retinopathy.

RESULTS

The prevalence of retinopathy was 39.3%. It has been noticed from this study findings, that the progression of retinopathy is been influenced by five independent risk factors such as duration of diabetes, presence neuropathy, total cholesterol at second and third visit and createnine clearance.

CONCLUSION

DR is highly prevalent among type 2 DM. The progression of retinopathy is been influenced by five independent risk factors such as duration of diabetes, presence neuropathy, total cholesterol at second and third visit and createnine clearance. DR is a serious diabetic complication and public health strategies are required in order to reduce its risk factors and decrease its prevalence.

Link between retinopathy and nephropathy caused by complications of diabetes mellitus type 2

While the correlation and chronology of appearance of diabetic nephropathy and retinopathy is well known in diabetes mellitus (DM) type 1 patients, in DM type 2 this correlation is less clear. A retrospective study including 917 patients with type 2 diabetes. Diabetic retinopathy (DR) was diagnosed based on fundus photographs taken with a non-mydriatic camera. Diabetic nephropathy (DN) was diagnosed based on urinary albumin concentration in a morning urine sample. Statistical analysis was performed with a seemingly unrelated regression (SUR) model. Our SUR model is statistically significant: the test for "model versus saturated" is 2.20 and its significance level is 0.8205. The model revealed that creatinine and glomerular filtration rate (GFR) have strong influence on albuminuria, while body mass index (BMI) and HbA1c have less significant impact. DR is affected positively by diabetes duration, insulin treatment, glucose levels, and HbA1c, and it is affected negatively by GFR, triglyceride levels, and BMI. The association between DR and DN was statistically significant and had a unidirectional correlation, which can be explained by chronological order; that is, DN precedes DR. The present study indicates that the level of renal impairment is proportional to the level of damage to the eye. Furthermore, such an association has a chronological aspect; the renal injury precedes retinal damage.

Genetics in diabetic retinopathy: current concepts and new insights

There is emerging evidence which indicates the essential role of genetic factors in the development of diabetic retinopathy (DR). In this regard it should be highlighted that genetic factors account for 25-50% of the risk of developing DR. Therefore, the use of genetic analysis to identify those diabetic patients most prone to developing DR might be useful in designing a more individualized treatment. In this regard, there are three main research strategies: candidate gene studies, linkage studies and Genome-Wide Association Studies (GWAS). In the candidate gene approach, several genes encoding proteins closely related to DR development have been analyzed. The linkage studies analyze shared alleles among family members with DR under the assumption that these predispose to a more aggressive development of DR. Finally, Genome-Wide Association Studies (GWAS) are a new tool involving a massive evaluation of single nucleotide polymorphisms (SNP) in large samples. In this review the available information using these three methodologies is critically analyzed. A genetic approach in order to identify new candidates in the pathogenesis of DR would permit us to design more targeted therapeutic strategies in order to decrease this devastating complication of diabetes. Basic researchers, ophthalmologists, diabetologists and geneticists should work together in order to gain new insights into this issue.

Four-year incidence of diabetic retinopathy in a Spanish cohort: the MADIABETES study

Objective

To evaluate the incidence of diabetic retinopathy in patients with Type 2 Diabetes Mellitus, to identify the risk factors associated with the incidence of retinopathy and to develop a risk table to predict four-year retinopathy risk stratification for clinical use, from a four-year cohort study.

Design

The MADIABETES Study is a prospective cohort study of 3,443 outpatients with Type 2 Diabetes Mellitus, sampled from 56 primary health care centers (131 general practitioners) in Madrid (Spain).

Results

The cumulative incidence of retinopathy at four-year follow-up was 8.07% (95% CI = 7.04–9.22) and the incidence density was 2.03 (95% CI = 1.75–2.33) cases per 1000 patient-months or 2.43 (95% CI = 2.10–2.80) cases per 100 patient-years. The highest adjusted hazard ratios of associated risk factors for incidence of diabetic retinopathy were LDL-C >190 mg/dl (HR = 7.91; 95% CI = 3.39–18.47), duration of diabetes longer than 22 years (HR = 2.00; 95% CI = 1.18–3.39), HbA1c>8% (HR = 1.90; 95% CI = 1.30–2.77), and aspirin use (HR = 1.65; 95% CI = 1.22–2.24). Microalbuminuria (HR = 1.17; 95% CI = 0.75–1.82) and being female (HR = 1.12; 95% CI = 0.84–1.49) showed a non-significant increase of diabetic retinopathy. The greatest risk is observed in females who had diabetes for more than 22 years, with microalbuminuria, HbA1c>8%, hypertension, LDL-Cholesterol >190 mg/dl and aspirin use.

Conclusions

After a four-year follow-up, the cumulative incidence of retinopathy was relatively low in comparison with other studies. Higher baseline HbA1c, aspirin use, higher LDL-Cholesterol levels, and longer duration of diabetes were the only statistically significant risk factors found for diabetic retinopathy incidence. This is the first study to demonstrate an association between aspirin use and diabetic retinopathy risk in a well-defined cohort of patients with Type 2 Diabetes Mellitus at low risk of cardiovascular events. However, further studies with patients at high cardiovascular and metabolic risk are needed to clarify this issue.

Diabetic retinopathy is associated with oxidative stress and mitigation of gene expression of antioxidant enzymes

Type 2 diabetes is a metabolic disease associated with serious complications, including diabetic retinopathy (DR). The authors' main aim was to investigate biochemical parameters and the oxidative stress associated with the type 2 DR patients and to study gene expression of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) among patients with DR [DR(+)] compared with a control nondiabetic group. In all, 67 patients with DR included in this study were diabetic for more than 10 years. Among them, 22 patients were DR(+), and 45 patients did not have DR [DR(-)]. The subjects' age range was 14 years to 80 years old with diabetes duration range between 2 and 45 years. Body mass index (BMI) was 31.43 ± 5.94 and 32.33 ± 6.54, systolic blood pressure was 117.15 ± 18.16 mmHg and 126.15 ± 20.26 mmHg, diastolic blood pressure was 81.11 ± 10.55 mmHg and 82.77 ± 10.85 mmHg, HbA1c was 7.2 ± 1.1 and 8.19 ± 1.95, serum total cholesterol was 6.61 ± 1.11 and 4.11 ± 0.31, serum triglycerides were 3.52 ± 0.89 and 3.42 ± 0.79, serum low-density lipoprotein (LDL) was 2.12 ± 0.10 and 2.42 ± 0.15, high-density lipoprotein (HDL) was 2.66 ± 0.30 and 2.55 ± 0.21, SOD was 3.12 ± 0.87 and 1.53 ± 0.14, GPx was 11.14 ± 2.21 and 8.2 ± 1.84, CAT was 26.43 ± 3.34 and 9.60 ± 2.14, for DR(-) and DR(+) patients, respectively. SOD, GPx and CAT polymerase chain reaction (PCR) products of the DR(+) patients revealed the diminished expression of CAT gene followed by GPx and SOD genes. All were significant compared with the normal controls, P < 0.05. Linear regression analysis revealed a strong significant positive correlation between the retinopathy grade and the diastolic blood pressure, diabetes duration, hemoglobin A1c (HA1c)%, and fasting blood glucose (P < 0.001). A marginally significant positive correlation between the retinopathy grade and LDL-cholesterol was observed (P < 0.05), and a significant negative correlation between the retinopathy grade and total cholesterol was observed (P < 0.05). Poor glycemic control and alteration in mRNA gene expression of antioxidant enzymes are strongly associated with development of DR and the regular screening is mandatory for early detection and treatment.

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.

Determination of diabetic retinopathy prevalence and associated risk factors in Chinese diabetic and pre-diabetic subjects: Shanghai diabetic complications study

BACKGROUND

The prevalence of diabetic retinopathy is not well studied in the Chinese pre-diabetic population, also known as impaired glucose regulation. Hence, we investigated the prevalence of and risk factors associated with retinopathy in diabetic and pre-diabetic subjects from Chinese communities.

METHODS

A total of 3736 Chinese subjects were recruited from urban communities in Shanghai. The participants were classified as normal glucose tolerance, impaired glucose regulation (IGR) and diabetes based on the 75 g oral glucose tolerance test. The levels of diabetic retinopathy (DR) were assessed with non-mydriatic retinal photographs according to the Diabetic Retinopathy Disease Severity Scale.

RESULTS

The prevalence of diabetic retinopathy in patients with diabetes and impaired glucose regulation subjects was 9.4% and 2.5%, respectively. In subjects with IGR, hypertension (odds ratio: 3.54, p = 0.028), including elevated systolic and diastolic blood pressure and obesity (odds ratio: 3.53, p = 0.028) were significantly associated with diabetic retinopathy after age and sex adjustments. The factors associated with retinopathy in diabetes included diabetes duration, blood glucose levels, glycated hemoglobin levels, and the presence of albuminuria. Diabetic retinopathy was significantly associated with fasting plasma glucose in known diabetes, whereas in newly-diagnosed subjects, diabetic neuropathy was closely correlated to postprandial plasma glucose.

CONCLUSIONS

Hyperglycemia was a strong risk factor for diabetic retinopathy. In pre-diabetic subjects, diabetic retinopathy was also associated with hypertension and obesity.

Factors associated with diabetic retinopathy in chinese patients with type 2 diabetes mellitus

Objective. To investigate the risk factors of DR in Chinese T2DM patients. Methods. 2009 patients with T2DM were included in this cross-sectional study. All patients underwent eye examination, and the DR stage was defined by an ophthalmologist. Correlation analysis was performed to evaluate the relation between DR and clinical variables. Logistic regression models were used to assess risk for those factors associated with DR. Results. A total of 597 T2DM patients (29.7%) had DR, of which 548 (27.3%) were nonproliferative diabetic retinopathy and 49 (2.4%) were proliferative diabetic retinopathy. Positive correlations were found between DR and duration of diabetes, systolic blood pressure (SBP), diastolic blood pressure, glycated hemoglobin, glycated albumin, 24 hurinary albumin excretion, peripheral atherosclerosis (PA), diabetes nephropathy (DN), diabetic peripheral neuropathy, and anemia. Negative correlations were found between DR and C-peptide and glomerular filtration rate. Logistic regression analysis revealed that duration of diabetes, SBP, DN, anemia, PA, and C-peptide were each independent risk factors of DR. Conclusion. The duration of diabetes, SBP, DN, anemia, and PA are positively associated with DR in Chinese T2DM patients, while C-peptide is negatively associated with DR. Monitoring and evaluation of these related factors will likely contribute to the prevention and treatment of DR.

Prevalence and associated factors of diabetic retinopathy in rural Korea: the Chungju metabolic disease cohort study

This study was aimed to investigate the prevalence of diabetic retinopathy and its associated factors in rural Korean patients with type 2 diabetes. A population-based, cross-sectional diabetic retinopathy survey was conducted from 2005 to 2006 in 1,298 eligible participants aged over 40 yr with type 2 diabetes identified in a rural area of Chungju, Korea. Diabetic retinopathy was diagnosed by a practicing ophthalmologist using funduscopy. The overall prevalence of diabetic retinopathy in the population was 18% and proliferative or severe non-proliferative form was found in 5.0% of the study subjects. The prevalence of retinopathy was 6.2% among those with newly diagnosed type 2 diabetes and 2.4% of them had a proliferative or severe non-proliferative diabetic retinopathy. The odds ratio of diabetic retinopathy increased with the duration of diabetes mellitus (5-10 yr: 5.2- fold; > 10 yr: 10-fold), postprandial glucose levels (> 180 mg/dL: 2.5-fold), and HbA1c levels (every 1% elevation: 1.34-fold). The overall prevalence of diabetic retinopathy in rural Korean patients was similar to or less than that of other Asian group studies. However, the number of patients with proliferative or severe non-proliferative diabetic retinopathy was still high and identified more frequently at the time of diagnosis. This emphasizes that regular screening for diabetic retinopathy and more aggressive management of glycemia can reduce the number of people who develop diabetic retinopathy.

Incidence of diabetic retinopathy in a Hong Kong Chinese population

BACKGROUND

The aim was to examine the progression and regression of diabetic retinopathy within a four-year period in a Chinese population with type 2 diabetes mellitus in a community optometry clinic in Hong Kong.

METHODS

During the period May 2005 to November 2009, 5,160 patients with type 2 diabetes mellitus who had attended at least two diabetic retinopathy screening sessions at a community optometry clinic were included as subjects in this study. All had retinal photographs taken of both eyes, which were of sufficiently good quality for grading. For the purpose of this study, diabetic retinopathy grading was based on the results of the worst eye. The main outcomes were the within four-year incidence of diabetic retinopathy and the incidence of progression and regression of diabetic retinopathy.

RESULTS

Of the 5,160 subjects in this study, 3,647 had no diabetic retinopathy, while 1,513 had diabetic retinopathy at the baseline visit. Of those 3,647 subjects with no diabetic retinopathy, the within four-year cumulative incidence of any diabetic retinopathy, mild or moderate non-proliferative diabetic retinopathy and sight-threatening diabetic retinopathy was 15.16 per cent, 14.45 per cent, 0.69 per cent and 0.03 per cent, respectively. Of those 1,513 subjects with diabetic retinopathy at baseline, the within four-year progression incidence of diabetic retinopathy was 6.61 per cent and the regression incidence of diabetic retinopathy was 45.54 per cent.

CONCLUSION

The high regression incidence of diabetic retinopathy suggests that it might not be necessary for all patients with diabetes to be screened annually. Other methods to determine the screening frequency for an individual patient should be explored.

Albuminuria and Diabetic Retinopathy in Type 2 Diabetes Mellitus Sankara Nethralaya Diabetic Retinopathy Epidemiology And Molecular Genetic Study (SN-DREAMS, report 12)

BACKGROUND

The concordance of microalbuminuria and diabetic retinopathy (DR) has been well reported in persons with type 1 diabetes; however, for type 2 diabetes, there is paucity of data especially from population-based studies. The aim of this study was to estimate the prevalence of albuminuria (micro - and macroalbuminuria) among persons with type 2 diabetes and determine its role as a risk factor for presence and severity of DR.

METHODS

A population-based cross sectional study was conducted in cohort of 1414 subjects with type 2 diabetes from Chennai metropolis. All the subjects underwent comprehensive eye examination including 45 degrees four-field stereoscopic digital photography. DR was clinically graded using Early Treatment Diabetic Retinopathy Study scales. A morning urine sample was tested for albuminuria. Subjects were considered to have microalbuminuria, if the urinary albumin excretion was between 30 and 300 mg/24 hours, and macroalbuminuria at more than 300 mg/24 hours. The statistical software used was SPSS for Windows, Chicago, IL. Student t-test for comparing continuous variables, and χ2 test, to compare proportions amongst groups were used.

RESULTS

The prevalence of microalbuminuria in the study subjects was 15.9% (226/1414), and that of macroalbuminuria, 2.7% (38/1414). Individuals with macroalbuminuria in comparison to micro- or normoalbuminuria showed a greater prevalence of DR (60.5% vs. 31.0% vs. 14.1%, p < 0.001), and also a greater severity of the disease (60.9% vs. 21.4 vs. 9.9, p < 0.001).

CONCLUSIONS

Every 6th individual in the population of type 2 diabetes is likely to have albuminuria. Subjects with microalbuminuria were around 2 times as likely to have DR as those without microalbuminuria, and this risk became almost 6 times in the presence of macroalbuminuria.

Hemoglobin A1c and fasting plasma glucose levels as predictors of retinopathy at 10 years: the French DESIR study

OBJECTIVE

To evaluate the predictive values of hemoglobin A(1c) (HbA(1c)) and fasting plasma glucose (FPG) for retinopathy 10 years after the baseline examination.

METHODS

Seven hundred men and women from the DESIR (Data From an Epidemiological Study on the Insulin Resistance Syndrome) Study underwent evaluation for retinopathy using a nonmydriatic digital camera. During the preceding 9 years, 235 had diabetes mellitus (treated or FPG level of ≥126 mg/dL at least once), 227 had an impaired FPG level (110-125 mg/dL) at least once, and 238 always had glucose levels within reference limits (<110 mg/dL).

RESULTS

Compared with those without retinopathy, the 44 participants with retinopathy at 10 years had higher baseline mean (SD) levels of FPG (130 [49] vs 106 [22] mg/dL) and HbA(1c) (6.4% [1.6%] vs 5.7% [0.7%]) (both, P < .001). The frequency of retinopathy at 10 years, standardized according to the distribution of glycemia across the entire DESIR population, was 3.6%. In our population, FPG levels of 108 and 116 mg/dL had positive predictive values of 8.4% and 14.0%, respectively, for retinopathy at 10 years; HbA(1c) levels of 6.0% and 6.5% had positive predictive values of 6.0% and 14.8%, respectively. After 10 years of follow-up, retinopathy was equally frequent in participants with impaired FPG levels and in those who became diabetic during the study (8.6% and 6.7%, respectively), lower than in those with diabetes at baseline (13.9%).

CONCLUSION

Because the positive predictive values for retinopathy increase sharply from 108 mg/dL for FPG and from 6.0% for HbA(1c) levels, these thresholds are proposed to identify those at risk of retinopathy 10 years later.

Identification of Diabetic Retinopathy Genes through a Genome-Wide Association Study among Mexican-Americans from Starr County, Texas

To identify genetic loci for severe diabetic retinopathy, 286 Mexican-Americans with type 2 diabetes from Starr County, Texas, completed physical examinations including fundus photography for diabetic retinopathy grading. Individuals with moderate-to-severe non-proliferative and proliferative diabetic retinopathy were defined as cases. Direct genotyping was performed using the Affymetrix GeneChip Human Mapping 100 K Set, and SNPs passing quality control criteria were used to impute markers available in HapMap Phase III Mexican population (MXL) in Los Angeles, California. Two directly genotyped markers were associated with severe diabetic retinopathy at a P-value less than .0001: SNP rs2300782 (P = 6.04 × 10(-5)) mapped to an intron region of CAMK4 (calcium/calmodulin-dependent protein kinase IV) on chromosome 5, and SNP rs10519765 (P = 6.21 × 10(-5)) on chromosomal 15q13 in the FMN1 (formin 1) gene. Using well-imputed markers based on the HapMap III Mexican population, we identified an additional 32 SNPs located in 11 chromosomal regions with nominal association with severe diabetic retinopathy at P-value less than .0001. None of these markers were located in traditional candidate genes for diabetic retinopathy or diabetes itself. However, these signals implicate genes involved in inflammation, oxidative stress and cell adhesion for the development and progression of diabetic retinopathy.

Prediction of incident stroke events based on retinal vessel caliber: a systematic review and individual-participant meta-analysis

The caliber of the retinal vessels has been shown to be associated with stroke events. However, the consistency and magnitude of association, and the changes in predicted risk independent of traditional risk factors, are unclear. To determine the association between retinal vessel caliber and the risk of stroke events, the investigators combined individual data from 20,798 people, who were free of stroke at baseline, in 6 cohort studies identified from a search of the Medline (National Library of Medicine, Bethesda, Maryland) and EMBASE (Elsevier B.V., Amsterdam, the Netherlands) databases. During follow-up of 5-12 years, 945 (4.5%) incident stroke events were recorded. Wider retinal venular caliber predicted stroke (pooled hazard ratio = 1.15, 95% confidence interval: 1.05, 1.25 per 20-micron increase in caliber), but the caliber of retinal arterioles was not associated with stroke (pooled hazard ratio = 1.00, 95% confidence interval: 0.92, 1.08). There was weak evidence of heterogeneity in the hazard ratio for retinal venular caliber, which may be attributable to differences in follow-up strategies across studies. Inclusion of retinal venular caliber in prediction models containing traditional stroke risk factors reassigned 10.1% of people at intermediate risk into different, mostly lower, risk categories.

Six-year retrospective follow-up study of safe screening intervals for sight-threatening retinopathy in patients with diabetes mellitus

BACKGROUND

We estimate safe screening intervals for sight-threatening diabetic retinopathy (STDR).

METHODS

A 6-year retrospective follow-up study to review screening results of two cohorts of patients with diabetes mellitus (DM) was conducted; a cohort free of diabetic retinopathy (DR) and a cohort with mild nonproliferative diabetic retinopathy (NPDR) at baseline. Patients had been screened by means of a nonmydriatic retinal camera. Baseline age, sex, and diabetes characteristics were also collected. Statistical analysis was based on life-table method of risk estimation.

RESULTS

A total of 286 patients with DM free of DR and 144 patients with mild NPDR at baseline were included in the study. For patients free of DR, the probability of remaining free of STDR was 97% (95% confidence interval [CI] 94-99%) at the end of the fourth year. In this cohort of patients, those with type 2 DM were more likely to progress to STDR than those who had type 1 DM (p < .01). For patients with mild NPDR, the probability of remaining free of STDR dropped to 94% (95% CI 88-97%) at the end of the second year, and it was still 100% at the end of the second year for those with a glycated hemoglobin level < or =7.5% at baseline (p < .05).

CONCLUSIONS

Screening at a 3-4 year interval for diabetes patients free of DR is safe because of their low risk of developing STDR. Patients with mild NPDR require screening at a 1 year interval, or at a 2 year interval with good metabolic control.

Incidence and progression of diabetic retinopathy in Hong Kong Chinese with type 2 diabetes mellitus

OBJECTIVE

We conducted a cohort study to determine the incidence and progression of diabetic retinopathy (DR) in a Chinese population with type 2 diabetes mellitus in a district hospital in Hong Kong, and to identify the risk factors associated with the development and progression of DR over 4 years.

RESEARCH DESIGN AND METHODS

A total of 413 type 2 diabetic patients who followed up in our diabetic clinic and had a diabetic complication screening performed in 2001 were studied. The final analysis included 354 subjects (85.7%) after a mean follow-up period of 4.2 years. The severity of DR was graded according to the modified Early Treatment Diabetic Retinopathy Study (ETDRS). The relationship between clinical variables and DR development and progression was determined.

RESULTS

The baseline prevalence of DR was 39.2%. On 4-year follow-up, the incidence of DR was 20.3% (43 of 212). In those with baseline DR, 34.7% (42 of 121) progressed by >or=2 steps in ETDRS. On multivariate analysis, a high baseline glycosylated hemoglobin (HbA(1c)) was the only predictor of DR development, while macroalbuminuria and high mean HbA(1c) predicted progression. Regression of DR, defined by a >or=2-step decrement in ETDRS, occurred in 13.2% (12 of 91) of subjects and was associated with lower baseline HbA(1c) and absence of albuminuria.

CONCLUSION

The incidence of DR in our study was similar to--but progression of DR was higher than--those reported in Caucasians. More frequent retinal screening should be offered to those with baseline DR, high HbA(1c), or albuminuria. Good glycemic control is important in order to prevent the development and progression of DR, and can lead to regression of DR.

Association between plasma osteoprotegerin concentrations and urinary albumin excretion in Type 2 diabetes

AIMS

Osteoprotegerin (OPG) is a recently identified inhibitor of bone resorption. Recent studies indicate that OPG is also associated with endothelial dysfunction in Type 2 diabetes. The aim was to investigate the relationship between plasma OPG levels and urinary albumin excretion (UAE) in Type 2 diabetic patients.

METHODS

This study included 154 newly diagnosed Type 2 diabetic patients and 46 healthy subjects. Plasma OPG and 24-h UAE were measured. High-resolution ultrasound was used to measure flow-mediated (endothelium-dependent arterial) dilation (FMD).

RESULTS

Compared with the normoalbuminuric subgroup, OPG levels in the microalbuminuric subgroup were significantly higher, and OPG levels in macroalbuminuria subgroup were significantly higher than those in the normoalbuminuria and albuminuria subgroups. Multiple regression analysis showed that only FMD (r = -0.26), C-reactive protein (r = 0.23), fasting blood glucose (r = 0.25), 2-h blood glucose (r = 0.21), HbA(1c) (r = 0.28), UAE (r = 0.27) and retinopathy (r = 0.27) were significant factors associated with OPG. Pearson's correlation analyses showed a positive correlation between OPG and logUAE (r = 0.440) and negative correlations between OPG and FMD (r = -0.284), and between FMD and logUAE (r = -0.602).

CONCLUSIONS

Plasma OPG levels are significantly associated with UAE in Type 2 diabetic patients.

Four years incidence of diabetic retinopathy and effective factors on its progression in type II diabetes

PURPOSE

To study the 4 years incidence of diabetic retinopathy in patients with type II diabetes and effective factors on its progression.

METHODS

Among diabetic patients referred to Yazd Diabetes Research Center, 120 patients with type II diabetes without diabetic retinopathy were selected. After complete ophthalmic examination, fasting blood sugar (FBS), postprandial blood sugar, triglyceride, and cholesterol were measured and height, weight, and blood pressure (BP) were recorded. Then patients were followed with eye examination yearly for 4 years.

RESULTS

Four-year cumulative incidence of diabetic retinopathy was 47.5% (95% CI: 38.6-56.4). The retinopathy was mild nonproliferative diabetic retinopathy (NPDR) in 43 (35.8%) whereas 10 (8.3%) patients had moderate NPDR, 3 (2.5%) patients had severe NPDR, and only one patient had proliferative diabetic retinopathy. The incidence of diabetic retinopathy was 5.8% in first year, 20.3% in the second year, 24.4% in the third year, and 7.4% in the fourth year. Duration of diabetes, FBS, and systolic BP had statistically significant relation with grades of diabetic retinopathy. However, there was no significant association between age, sex, body mass index, triglyceride, cholesterol, method of treatment, smoking, and diastolic BP with grades of diabetic retinopathy.

CONCLUSIONS

These data provide 4-year cumulative incidence of diabetic retinopathy in defined type 2 diabetic patients. The present study shows that duration of diabetes, hyperglycemia, and systolic BP appear to be the major factors associated with the development of any level of retinopathy in type 2 diabetic patients.

Heritability of the severity of diabetic retinopathy: the FIND-Eye study

PURPOSE

Diabetic retinopathy (DR) and diabetic nephropathy (DN) are serious microvascular complications of diabetes mellitus. Correlations between severity of DR and DN and computed heritability estimates for DR were determined in a large, multiethnic sample of diabetic families. The hypothesis was that (1) the severity of DR correlates with the presence and severity of nephropathy in individuals with diabetes mellitus, and (2) the severity of DR is under significant familial influence in members of multiplex diabetic families.

METHODS

The Family Investigation of Nephropathy and Diabetes (FIND) was designed to evaluate the genetic basis of DN in American Indians, European Americans, African Americans, and Mexican Americans. FIND enrolled probands with advanced DN, along with their diabetic siblings who were concordant and discordant for nephropathy. These diabetic family members were invited to participate in the FIND-Eye study to determine whether inherited factors underlie susceptibility to DR and its severity. FIND-Eye participants underwent eye examinations and had fundus photographs taken. The severity of DR was graded by using the Early Treatment Diabetic Retinopathy Study Classification (ETDRS). Sib-sib correlations were calculated with the SAGE 5.0 program FCOR, to estimate heritability of retinopathy severity.

RESULTS

This report summarizes the results for the first 2368 diabetic subjects from 767 families enrolled in FIND-Eye; nearly 50% were Mexican American, the largest single ethnicity within FIND. The overall prevalence of DR was high; 33.4% had proliferative DR; 7.5%, 22.8%, and 9.5% had severe, moderate, and mild nonproliferative DR, respectively; 26.6% had no DR. The severity of DR was significantly associated with severity of DN, both by phenotypic category and by increasing serum creatinine concentration (chi(2) = 658.14, df = 20; P < 0.0001). The sib-sib correlation for DR severity was 0.1358 in the total sample and 0.1224 when limited to the Mexican-American sample. Broad sense heritabilities for DR were 27% overall and 24% in Mexican-American families. The polygenic heritability of liability for proliferative DR approximated 25% in this FIND-Eye sample.

CONCLUSIONS

These data confirm that the severity of DR parallels the presence and severity of nephropathy in individuals with diabetes mellitus. The severity of DR in members of multiplex diabetic families appears to have a significant familial connection.

Longitudinal association of glucose metabolism with retinopathy: results from the Australian Diabetes Obesity and Lifestyle (AusDiab) study

OBJECTIVE

We determined the longitudinal association of glucose metabolism with retinopathy in a sample of the Australian population.

RESEARCH DESIGN AND METHODS

The Australian Diabetes Obesity and Lifestyle (AusDiab) study is a national, longitudinal study of adults aged > or =25 years from 42 randomly selected areas of Australia. Retinopathy was assessed at baseline in 1999-2000 and 5 years later in 2004-2005 in participants identified as having diabetes (based on self-report and oral glucose tolerance test) and impaired glucose metabolism and in a random sample with normal glucose tolerance. Complete retinal data were available for 1,192 participants. Photographs were graded at two time points according to a simplified version of the Wisconsin grading system.

RESULTS

The 5-year incidences of retinopathy were 13.9 and 3.0% among those with known and newly diagnosed diabetes at baseline, respectively. Of those who developed incident newly diagnosed diabetes at follow-up, 11.9% had retinopathy at baseline compared with 5.6% of those who did not progress to incident newly diagnosed diabetes (P = 0.037). After adjustment for factors identified as risk factors for diabetes, individuals with retinopathy signs at baseline were twice as likely to develop incident newly diagnosed diabetes compared with those who did not have retinopathy signs at baseline.

CONCLUSIONS

The 5-year incidence of retinopathy was 13.9% among individuals with known diabetes. Nondiabetic individuals with retinopathy signs at baseline had a twofold higher risk of developing incident newly diagnosed diabetes 5 years later. This result provides further evidence that mild retinopathy signs may be a preclinical marker of underlying microvascular disease and future diabetes risk.

Proliferative diabetic retinopathy is associated with microalbuminuria in patients with type 2 diabetes

Diabetic retinopathy is one of the leading causes of blindness in working-age individuals. Diabetic patients with proteinuria or those on dialysis usually present severe forms of diabetic retinopathy, but the association of diabetic retinopathy with early stages of diabetic nephropathy has not been entirely established. A cross-sectional study was conducted on 1214 type 2 diabetic patients to determine whether microalbuminuria is associated with proliferative diabetic retinopathy in these patients. Patients were evaluated by direct and indirect ophthalmoscopy and grouped according to the presence or absence of proliferative diabetic retinopathy. The agreement of diabetic retinopathy classification performed by ophthalmoscopy and by stereoscopic color fundus photographs was 95.1% (kappa = 0.735; P < 0.001). Demographic information, smoking history, anthropometric and blood pressure measurements, glycemic and lipid profile, and urinary albumin were evaluated. On multiple regression analysis, diabetic nephropathy (OR = 5.18, 95% CI = 2.91-9.22, P < 0.001), insulin use (OR = 2.52, 95% CI = 1.47-4.31, P = 0.001) and diabetes duration (OR = 1.04, 95% CI = 1.01-1.07, P = 0.011) were positively associated with proliferative diabetic retinopathy, and body mass index (OR = 0.90, 95% CI = 0.86-0.96, P < 0.001) was negatively associated with it. When patients with macroalbuminuria and on dialysis were excluded, microalbuminuria (OR = 3.3, 95% CI = 1.56-6.98, P = 0.002) remained associated with proliferative diabetic retinopathy. Therefore, type 2 diabetic patients with proliferative diabetic retinopathy more often presented renal involvement, including urinary albumin excretion within the microalbuminuria range. Therefore, all patients with proliferative diabetic retinopathy should undergo an evaluation of renal function including urinary albumin measurements.

Genome-wide linkage analyses to identify Loci for diabetic retinopathy

Hyperglycemia and long duration of diabetes are widely recognized risk factors for diabetic retinopathy, but inherited susceptibility may also play a role because retinopathy aggregates in families. A genome-wide linkage analysis was conducted in 211 sibships in which > or =2 siblings had diabetes and retinal photographs were available from a longitudinal study. These sibships were a subset of 322 sibships who had participated in a previous linkage study of diabetes and related traits; they comprised 607 diabetic individuals in 725 sibpairs. Retinal photographs were graded for presence and severity of diabetic retinopathy according to a modification of the Airlie House classification system. The grade for the worse eye was adjusted for age, sex, and diabetes duration and analyzed as a quantitative trait. Heritability of diabetic retinopathy in this group was 18% (95% CI 2-36). A genome-wide linkage analysis using variance components modeling found evidence of linkage on chromosome 1p. Using single-point analysis, the peak logarithm of odds (LOD) was 3.1 for marker D1S3669 (34.2 cM), whereas with multipoint analysis the peak LOD was 2.58 at 35 cM. No other areas of suggestive linkage were found. We propose that an area on chromosome 1 may harbor a gene or genes conferring susceptibility to diabetic retinopathy.

Biologic risk factors associated with diabetic retinopathy: the Los Angeles Latino Eye Study

OBJECTIVE

To identify biologic risk factors associated with having diabetic retinopathy (DR) in Latinos with type 2 diabetes mellitus (T2DM).

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Six thousand three hundred fifty-seven Latinos ages > or =40 years from 6 census tracts in Los Angeles, California.

METHODS

An in-home interview was administered to all participants in the Los Angeles Latino Eye Study (LALES). All participants diagnosed with T2DM underwent a complete ophthalmologic examination including stereoscopic fundus photography (7 standard Early Treatment Diabetic Retinopathy Study fields). Photographs were graded in a masked manner using a modified Airlie House grading system to assess presence and severity of DR. Univariate and stepwise logistic regression analyses were used to identify independent risk factors.

MAIN OUTCOME MEASURES

Biologic risk factors associated with any DR and proliferative DR (PDR).

RESULTS

Of the 7789 eligible individuals in LALES, 6357 (82%) had a clinical examination. One thousand two hundred sixty-three participants had definite diabetes and 1187 Latinos had T2DM. Of those with T2DM, 46% (544) had DR. Stepwise logistic regression analyses revealed that compared with females, males had a 50% higher risk of having any DR (OR = 1.50; P = 0.006). Factors independently associated with a greater risk of having any DR were longer duration of known diabetes (per year, OR = 1.08, P<0.0001), higher glycosylated hemoglobin levels (per 1%, OR = 1.22, P<0.0001); higher systolic blood pressure (per 20 mmHg, OR = 1.26, P = 0.002); and insulin treatment (OR = 1.60, P = 0.01). Factors independently associated with PDR included longer duration of known diabetes (per year, OR = 1.06, P<0.0001); being on insulin treatment (OR = 3.2, P<0.0001); and a higher systolic blood pressure (per 20 mmHg, OR = 1.44, P = 0.01). The relationship of these variables to the risk of having DR or PDR is not a constant linear function in all cases and varies depending on the variable.

CONCLUSIONS

Our study showed that the high risk of DR in adult Latinos is independently associated with both nonmodifiable and modifiable risk factors. These findings suggest that controlling hyperglycemia and hypertension in this ethnic group may reduce the high risk of having DR associated with T2DM.

Six year incidence and progression of diabetic retinopathy: results from the Mauritius diabetes complication study

AIMS

To determine the incidence, progression and risk factors for diabetic retinopathy in the multiethnic population of Mauritius.

METHOD

A longitudinal, population-based study was conducted in Mauritius, during 1987, 1992 and 1998. Participants identified through the study as having diabetes (both known and newly diagnosed, by self-report and oral glucose tolerance test) and one in four participants with impaired glucose tolerance (IGT) underwent complications screening in 1992 and 1998. Retinal photographs were taken using a TRC-50VT retinal camera in three fields of the right eye (centred on the optic disc; macula (temporal to the optic disc); and nasal to disc). Photographs were graded according to a simplified version of the Wisconsin grading system.

RESULTS

The 6-year incidence of diabetic retinopathy was 23.8% (sight-threatening in 0.4%). Among those with known diabetes mellitus (KDM) and free of retinopathy at baseline the incidence of non-proliferative diabetic retinopathy (NPDR) was 29.2% and proliferative diabetic retinopathy (PDR) was 1.0%. Among those with newly diagnosed diabetes mellitus (NDM) at baseline the incidence of NPDR was 19.1% (no incident cases of PDR were found). Independent risk factors for retinopathy using the baseline population characteristics were duration of diabetes and fasting plasma glucose.

CONCLUSIONS

This is one of the few recent population-based studies of diabetic retinopathy undertaken in a developing nation. The incidence of retinopathy in Mauritius was high among those with NDM at baseline, with one in five developing retinopathy over 6 years. These results support the concept that screening for diabetes is important.