Prevalence of diabetic retinopathy in relation to age at onset of the diabetes, treatment, duration and glycemic control

Role of Systemic Factors in Improving the Prognosis of Diabetic Retinal Disease and Predicting Response to Diabetic Retinopathy Treatment

Topic

To review clinical evidence on systemic factors that might be relevant to update diabetic retinal disease (DRD) staging systems, including prediction of DRD onset, progression, and response to treatment.

Clinical relevance

Systemic factors may improve new staging systems for DRD to better assess risk of disease worsening and predict response to therapy.

Methods

The Systemic Health Working Group of the Mary Tyler Moore Vision Initiative reviewed systemic factors individually and in multivariate models for prediction of DRD onset or progression (i.e., prognosis) or response to treatments (prediction).

Results

There was consistent evidence for associations of longer diabetes duration, higher glycosylated hemoglobin (HbA1c), and male sex with DRD onset and progression. There is strong trial evidence for the effect of reducing HbA1c and reducing DRD progression. There is strong evidence that higher blood pressure (BP) is a risk factor for DRD incidence and for progression. Pregnancy has been consistently reported to be associated with worsening of DRD but recent studies reflecting modern care standards are lacking. In studies examining multivariate prognostic models of DRD onset, HbA1c and diabetes duration were consistently retained as significant predictors of DRD onset. There was evidence of associations of BP and sex with DRD onset. In multivariate prognostic models examining DRD progression, retinal measures were consistently found to be a significant predictor of DRD with little evidence of any useful marginal increment in prognostic information with the inclusion of systemic risk factor data apart from retinal image data in multivariate models. For predicting the impact of treatment, although there are small studies that quantify prognostic information based on imaging data alone or systemic factors alone, there are currently no large studies that quantify marginal prognostic information within a multivariate model, including both imaging and systemic factors.

Conclusion

With standard imaging techniques and ways of processing images rapidly evolving, an international network of centers is needed to routinely capture systemic health factors simultaneously to retinal images so that gains in prediction increment may be precisely quantified to determine the usefulness of various health factors in the prognosis of DRD and prediction of response to treatment.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Assessment of Prevalence and Risk Factors for Diabetic Retinopathy in Patients with Type 1 and Type 2 Diabetes Examined at a Tertiary Care

Introduction: Diabetic retinopathy (DR) is a microvascular complication of diabetes mellitus and the leading cause of visual impairment and blindness. The aim of the study was to estimate and compare the prevalence of DR and to determine an association between DR and systemic risk factors in hospitalized type 1 (DMT1) and type 2 (DMT2) diabetic patients. Material and methods: We analyzed 260 patients with diabetes, 43 with DMT1 and 217 with DMT2. The following data were collected: age, gender, type and duration of diabetes, glycemic control, blood pressure, estimated glomerular filtration rate, ophthalmologic examinations and routine biochemical parameters. Results: Out of the total number of 260 patients, 77 (29.6%) had non-proliferative DR (NPDR), 21 (8.1%) had proliferative DR (PDR), 29 (11.1%) had diabetic macular edema (DME), and 69 (23.5%) had diabetic cataracts. Forty-three (16.5%) patients were previously diagnosed with DMT1 and 217 (83.5%) with DMT2. The duration of diabetes was not significantly longer in DMT1 (12.8±11.2 years) in comparison to DMT2 (11.07±8.1 years). The prevalence of NPDR and PDR did not differ statistically in either groups. DME was more prevalent in DMT2 than in DMT1 (P<0.05). Diabetic cataract was found in 26.7% vs. 6.7% of patients with DMT2 and DMT1, respectively (p<0.01). The duration of diabetes significantly correlated with NPDR and PDR in DMT1 (r=o.31, p<0.05; r=0.55, p<0.001, respectively). In DMT2, significant correlations were found between the duration of diabetes and cataract, NPDR, PDR and DME (r=0.31, p<0.001; r=0.43 p<0.01, r=0.16 p<0.05 and r=0.20 p<0.01, respectively). Fasting plasma glucose (FPG) significantly correlated with PDR (r=0.258, p<0.05), while HbA1c with DME (r= 0.15 p<0.05). Conclusion: The duration of diabetes and hyperglycemia were associated with DR in both types of diabetes.

Predictive Value of the Advanced Lipoprotein Profile and Glycated Proteins on Diabetic Retinopathy

This study aimed to assess whether the advanced characteristics of serum lipoprotein subclasses could better predict the risk of developing diabetic retinopathy (DR) and its severity compared to other established risk factors in subjects with type 1 (T1D) and type 2 (T2D) diabetes. This observational, cross-sectional substudy analyzed DR-related data from 309 T1D and 264 T2D subjects. The advanced lipoprotein and glycoprotein profile was determined by nuclear magnetic resonance (NMR) spectroscopy (Liposcale test). NMR analysis of lipoproteins revealed that T1D subjects with DR showed standard non-HDL particles, despite higher IDL lipid concentrations. Notably, IDL lipids were elevated in T1D subjects with worsened DR. VLDL and LDL were smaller, whereas HDL triglycerides were increased in DR compared with non-DR. On the other hand, the T2D subjects with DR showed altered characteristics in the LDL fraction, mainly revealed by a significant decrease in smaller LDL and a reduction in LDL-C. Moreover, the glycoprotein profile did not reveal significant changes among DR groups, regardless of the type of diabetes. However, lipoprotein characteristics and glycoproteins unveiled by NMR analysis did not improve the predictive value of conventional lipids or other traditional, well-established biomarkers of DR in our cohorts.

Early-onset type 2 diabetes: A high-risk factor for proliferative diabetic retinopathy (PDR) in patients with microalbuminuria

We aim to explore the relationship between early-onset diabetes and proliferative diabetic retinopathy (PDR) in type 2 diabetes mellitus (T2DM) patients with microalbuminuria.A total of 461 T2DM patients with microalbuminuria were enrolled. Subjects were defined as early-onset or late-onset based on the age at which they were diagnosed with diabetes (<40 and ≥40 years, respectively). Medical history, anthropometry, and laboratory indicators were documented. PDR was defined as the presence of any of the following changes on fundus photography: neovascularization, vitreous hemorrhage, or preretinal hemorrhage.The prevalence of PDR was 6-fold higher in patients with early-onset than late-onset T2DM [(6.1% vs 1.0%), P = .004]. Univariate correlation analysis showed that early-onset diabetes, use of oral hypoglycemic drugs, and insulin therapy were risk factors for PDR. In multivariate logistic analysis, patients with early-onset diabetes exhibited a 7.00-fold [(95% confidence interval 1.40-38.26), P = .019] higher risk of PDR than subjects with late-onset diabetes after adjusting for sex; T2DM duration; systolic blood pressure; total triglyceride; glycated hemoglobin; insulin therapy; and the use of oral hypoglycemic drugs, antihypertensive drugs, and lipid-lowering drugs.In T2DM patients with microalbuminuria, early-onset diabetes is an independent risk factor for the development of PDR.

Cinnamon Attenuated Long-Term IGT-Induced Retinal Abnormalities via Regulation of Glucose Homeostasis in Neonatal Streptozotocin Induced Rat Model

Diabetic retinopathy (DR) is one of the major causes of blindness all over the world. According to the previous studies, impaired glucose tolerance (IGT) has been linked to retinal dysfunction/vascular damage. Decreased retinal function is an initial event of early DR. Although the biochemical and molecular events are not fully understood, glial activation, angiogenesis and oxidative stress are some of the pathways associated with early retinal abnormalities. Since IGT is associated with development of retinal dysfunction/vascular damage; as a preventive strategy, we have studied beneficial effect of Cinnamon as a hypoglycaemic agent on long-term IGT induced retinal abnormalities using neonatal streptozotocin (nSTZ) rat model. Control, IGT rats were maintained on AIN-93M diet alone and another set of IGT rats were maintained on AIN-93M diet with 3% Cinnamon for 8 months. At the end of the study, untreated IGT rats developed retinal functional abnormalities as assessed by electroretinogram (ERG) and the retinal structure did not alter as assessed by H&E staining. Further, increase in expressions of GFAP, VEGF and decreased expression of rhodopsin in untreated IGT rat retinas. 4-HNE, a marker of oxidative stress was also elevated in IGT state. Supplementation of Cinnamon to IGT rats had lowered fasting and postprandial glucose levels and also prevented retinal functional abnormalities. Further, Cinnamon protected photoreceptor cell damage, suppressed glial activation, angiogenesis and oxidative stress as there was an improved rhodopsin expression, inhibited elevated expressions of GFAP, VEGF and 4-HNE respectively. In conclusion, Cinnamon attenuated IGT induced retinal abnormalities probably through its hypoglycemic property.

Time to onset of type 2 diabetes mellitus in Ghana

BACKGROUND

Type 2 diabetes affects an increasing number of Ghanaians. The timing of the onset of diabetes is linked to several other co-morbid conditions, yet no study has examined the timing of the onset of type 2 diabetes in Ghana.

METHODS

To fill this gap in the literature, this study applied logit models to data extracted from the medical records at the Diabetes Clinic of the Komfo Anokye Teaching Hospital in Kumasi, Ghana. Gender-specific models were also estimated.

RESULTS

The results show that obesity was a significant predictor of the timing of the first onset of diabetes among both males and females. Women with high school education compared with no formal education, and female employees compared with the unemployed were more likely to experience an early onset of type 2 diabetes.

CONCLUSION

Policymakers must educate Ghanaians about behaviors that will reduce their risk of obesity and diabetes.

Effect of combination of chlorella intake and aerobic exercise training on glycemic control in type 2 diabetic rats

OBJECTIVES

Chlorella is a type of unicellular green algae that contains various nutrients. Habitual exercise and chlorella treatment can improve insulin resistance in obese or diabetic animal models. However, the additive effects of combined chlorella intake and aerobic exercise training remain unclear. The aim of this study was to investigate whether a combination of chlorella intake and aerobic exercise training would produce greater effects on improving glycemic control in rats with type 2 diabetes.

METHODS

Twenty-wk-old male rats with type 2 diabetes (Otsuka Long-Evans Tokushima Fatty [OLETF] rats) were randomly divided into four groups: sedentary control, aerobic exercise training (treadmill running for 1 h, 25m/min, 5 d/wk), chlorella intake (0.5% chlorella powder in normal diet), or combination of aerobic exercise training and chlorella intake for 8 wk (n = 7 per group).

RESULTS

Chlorella intake and aerobic exercise training significantly decreased fasting blood glucose, insulin levels, and total glucose area under the curve during the oral glucose tolerance test and increased the insulin sensitivity index concomitant with muscle phosphatidylinositol-3 kinase (PI3K) activity, protein kinase B (Akt) phosphorylation, and glucose transporter 4 (GLUT4) translocation levels. Furthermore, a combination of chlorella intake and aerobic exercise training significantly further improved these effects compared with aerobic exercise training or chlorella intake alone.

CONCLUSIONS

These results suggested that chlorella intake combined with aerobic exercise training had more pronounced effects on the improvement of glycemic control via further activation of muscle PI3K/Akt/GLUT4 signaling in rats with type 2 diabetes.

Early onset of type 2 diabetes among visible minority and immigrant populations in Canada

OBJECTIVES

Type 2 diabetes is a chronic condition that affects nearly over three million Canadians, including immigrants. The timing of the first onset of diabetes has been linked to several other severe diseases. Yet, there is a dearth of empirical studies that examine the timing of the first onset of diabetes among Canadians, in general, and among immigrants and ethnic minority populations within Canada, in particular.

DESIGN

Applying event history techniques to the 2013 Canadian Community and Health Survey, we address this research void by examining factors that contribute to the first onset of diabetes among immigrant and visible minority populations in Canada (N = 8905). Given the gendered patterns in the epidemiology of diseases and the differences in risk factors for men and women, gender-specific models were estimated.

RESULTS

Results showed that South Asian, Black and Filipino women developed diabetes earlier, compared to women from the UK. Similarly, South Asian, Chinese, Filipino, Black, South East Asian and Arab men developed diabetes earlier than men from the UK. A significant and important finding of this analysis was that the risks of developing diabetes vanished completely for Black and Filipino women, after accounting for lifestyle factors. For South Asian women, however, there was significant attenuation in their risks after accounting for lifestyle factors. The findings were strikingly different for immigrant men. Specifically, their risks of developing diabetes increased after accounting for lifestyle factors.

CONCLUSIONS

These results suggest the development of gender-specific and lifestyle interventions, targeted at specific immigrant groups with increased risks of developing diabetes earlier in the life course.

Fundus Photography as a Screening Method for Diabetic Retinopathy in Children With Type 1 Diabetes: Outcome of the Initial Photography

PURPOSE

To determine the success rate of the initial fundus photography session in producing gradable images for screening diabetic retinopathy in children <18 years of age with type 1 diabetes (T1D), and to analyze outcome-associated factors.

DESIGN

Retrospective observational cohort study.

METHODS

Mydriatic red-free monochromatic 60-degree digital fundus images centered on the macula and optic disc of 213 patients were graded. Photography success was classified as "complete" if both images of both eyes were gradable, "partial" if both images of 1 eye were gradable, "macula-centered image(s) only" if only the macula-centered image of one or both eyes was gradable, and "unsuccessful" if neither macula-centered image was gradable.

RESULTS

Complete success was reached in 97 (46%; 95% confidence interval [CI], 39-52) patients, at least partial success in 153 (72%; 95% CI, 65-78) patients, success of macula-centered image(s) only in 47 (22%; 95% CI, 17-28) patients, and in 13 (6%; 95%CI, 3-10) patients fundus photography was unsuccessful. Macula-centered images were more often gradable in both eyes than optic disc-centered images (P < .001). Success of photography did not differ between right and left eye. Sex, age at diagnosis of T1D, and the duration of diabetes, age, and glycemic control at the time of initial photography were unassociated with complete success. Partial success tended to decrease with increasing age category (P = .093), and the frequency of gradable macula-centered image(s) only increased with increasing age (P = .043).

CONCLUSIONS

Less than half of the children achieved complete success, but in only 6% initial fundus photography was unsuccessful, indicating its value in assessing retinopathy in the pediatric setting.

Association analysis of PPARγ (p.Pro12Ala) polymorphism with type 2 diabetic retinopathy in patients from north India

BACKGROUND

The present study aimed to examine the association of PPARγ (p.Pro12Ala) polymorphism with type 2 diabetic retinopathy (DR) in patients from north India.

MATERIAL AND METHODS

In this case-control association study a total of 1325 subjects (717 DR patients and 608 individuals with confirmed type 2 diabetes mellitus (T2DM) without retinopathy taken as controls (CDR)), were recruited. Genotyping for PPARγ (p.Pro12Ala) polymorphism was performed by Taqman SNP Genotyping Assays using Real time PCR.

RESULTS

Statistically significant differences were observed between the two analyzed groups in the duration of diabetes and random blood glucose levels (p = 0.000 and p = 0.011, respectively). However, genotype and allele frequency distribution of PPARγ (p.Pro12Ala) polymorphism did not differ significantly between DR and CDR groups (p = 0.507 and 0.625, respectively).

CONCLUSIONS

These findings suggest no significant association of p.Pro12Ala polymorphism with retinopathy in tested type 2 diabetic retinopathy patients as compared to T2DM individuals take as controls. To our knowledge, this is the first report of association analysis of p.Pro12Ala polymorphism in PPARγ in DR patients from India.

Improving visual prognosis of the diabetic patients during the past 30 years based on the data of the Finnish Register of Visual Impairment

PURPOSE

To evaluate changes in visual impairment (VI) due to diabetic retinopathy (DR) recorded in the Finnish Register of Visual Impairment (RVI) during the past 30 years.

METHODS

Data from the visually impaired diabetic persons included in the RVI were analysed using three 10-year cohorts (1982-90, 1991-2000, 2001-10). Information on the age at the time of the first VI registration, severity of VI determined according to the World Health Organisation (WHO) definition, and the age at death was collected. VI due to proliferative (PDR) and non-proliferative (NPDR) DR were analysed separately.

RESULTS

Data of 4080 patients whose primary cause for VI was DR were analysed. The median age at the time of notification of VI for the three cohorts was 39, 62 and 59 years in the PDR group and 71, 73 and 73 in the NPDR group, respectively. The proportion of blind persons was 42%, 22% and 15% in the PDR group and 10%, 9% and 4% in the NPDR group, respectively. The median age at death in the three cohorts was 54, 73 and 72 years in PDR group and 76, 79 and 80 years in the NPDR group, respectively. The standardized mortality ratio (SMR) compared with the general population was 8.3, 2.9 and 1.4 in persons with PDR and 3.4, 2.0 and 1.2 in those with NPDR, respectively.

CONCLUSIONS

A significant change in the profile of the VI in the PDR group has taken place in Finland. It was characterized by increased age at the time of VI notification, decreased severity of VI and higher age at death. Most evidently these improvements took place in the 1990s. The profile of VI in the NPDR group has changed only modestly. Compared with the general population, SMRs improved both in NPDR and PDR groups continuously.

Iranian risk model as a predictive tool for retinopathy in patients with type 2 diabetes

OBJECTIVE

Diabetic retinopathy (DR) is the leading cause of blindness in patients with type 1 or type 2 diabetes. The gold standard for the detection of DR requires expensive equipment. This study was undertaken to develop a simple and practical scoring system to predict the probability of DR.

METHODS

A total of 1782 patients who had first-degree relatives with type II diabetes were selected. Eye examinations were performed by an expert ophthalmologist. Biochemical and anthropometric predictors of DR were measured. Logistic regression was used to develop a statistical model that can be used to predict DR. Goodness of fit was examined using the Hosmer-Lemeshow test and the area under the receiver operating characteristic (ROC) curve.

RESULTS

The risk model demonstrated good calibration and discrimination (ROC area=0.76) in the validation sample. Factors associated with DR in our model were duration of diabetes (odds ratio [OR]=2.14, confidence interval [CI] 95%=1.87 to 2.45); glycated hemoglobin (A1C) (OR=1.21, CI 95%=1.13 to 1.30); fasting plasma glucose (OR=1.83, CI 95%=1.28 to 2.62); systolic blood pressure (OR=1.01, CI 95%= 1.00 to 1.02); and proteinuria (OR=1.37, CI 95%=1.01 to 1.85). The only factor that had a protective effect against DR were body mass index and education level (OR=0.95, CI 95%=0.92 to 0.98).

CONCLUSIONS

The good performance of our risk model suggests that it may be a useful risk-prediction tool for DR. It consisted of the positive predictors like A1C, diabetes duration, sex (male), fasting plasma glucose, systolic blood pressure and proteinuria, as well as negative risk factors like body mass index and education level.

Molecular and pathological studies in the posterior interosseous nerve of diabetic and non-diabetic patients with carpal tunnel syndrome

AIMS/HYPOTHESIS

We sought to establish the molecular and pathological changes predisposing diabetic and non-diabetic patients to the development of carpal tunnel syndrome (CTS).

METHODS

The posterior interosseous nerve (PIN) was biopsied in 25 diabetic and 19 non-diabetic patients undergoing carpal tunnel decompression for CTS. Detailed morphometric and immunohistological analyses were performed in the nerve biopsy.

RESULTS

In diabetic patients median nerve distal motor latency was prolonged (p < 0.05 vs non-diabetic patients), PIN myelinated fibre density (p < 0.05), fibre area (p < 0.0001) and axon area (p < 0.0001) were reduced, the percentage of unassociated Schwann cell profiles (p < 0.0001) and unmyelinated axon density (p < 0.0001) were increased and the axon diameter was reduced (p < 0.0001). Endoneurial capillary basement membrane area was increased (p < 0.0001) in diabetic patients, but endothelial cell number was increased (p < 0.01) and luminal area was reduced (p < 0.05) in non-diabetic patients with CTS. There was no difference in the expression of hypoxia-inducible factor 1α between diabetic and non-diabetic patients with CTS. However, the expression of vascular endothelial growth factor A (VEGF) (p < 0.05) and its receptors VEGFR-1 (p < 0.01) and VEGFR-2 (p < 0.05) was significantly increased in diabetic patients, particularly those with type 1 diabetes, and related to the severity of nerve fibre pathology.

CONCLUSIONS/INTERPRETATION

This study demonstrates increased nerve fibre and microvascular pathology in relation to enhanced expression of VEGF and its receptors in a non-compressed nerve in diabetic compared with non-diabetic patients with CTS. It therefore provides a potential molecular and pathological basis for the predisposition of diabetic patients to the development of CTS.

The prevalence of retinopathy in subjects with and without type 2 diabetes mellitus

PURPOSE

To evaluate the prevalence of and risk factors for, retinopathy in a geographically defined population with type 2 diabetes mellitus compared with a control group of subjects without diabetes, matched by age, sex and residence in order to find the retinopathy attributable to type 2 diabetes.

METHODS

The study populations are, on one hand, a prevalence cohort of subjects with type 2 diabetes resident in the community of Laxå, Sweden, and on the other a control group, matched by age, gender and residence with those with a diagnosis of type 2 diabetes mellitus. Retinopathy was graded from fundus photographs using a modification of the Early Treatment Retinopathy Study (ETDRS) adaptation of the modified Airlie House classification of diabetic retinopathy (DR).

RESULTS

Any retinopathy was found in 34.6% in the type 2 diabetes cohort and in 8.8% in the control group without diabetes. Among the diabetic patients, any retinopathy was significantly associated with duration of diabetes (p = 0.0001), HbA1c (p = 0.0056), systolic blood pressure (p = 0.0091) and lower serum cholesterol (p = 0.0197) in multivariate logistic regression analyses. Having retinopathy in the control group was associated only with systolic blood pressure (p = 0.0014) in logistic regression analysis.

CONCLUSIONS

The prevalence of retinopathy among patients with type 2 diabetes in Laxå, Sweden, was similar or somewhat lower compared with other studies in the Nordic countries. The prevalence of retinopathy in a control group without diabetes equalled numbers from population studies worldwide. Our study indicates that the retinopathy that can be attributed to hyperglycaemia in the diabetic state is less common than is usually accounted for. A considerable fraction of retinopathy in subjects with diabetes may instead be due to other factors such as hypertension and should thus be treated correspondingly.

Higher age at onset of type 1 diabetes increases risk of macular oedema

PURPOSE

To investigate whether age at onset of type 1 diabetes is a risk factor for clinically significant macular oedema (CSME).

METHODS

A sample of 1354 patients with a mean duration of diabetes 24.6 ± 11.6 years was drawn from the FinnDiane Study population and divided into age at onset groups 0-4 (n = 184), 5-14 (n = 662) and 15-40 years (n = 508). Type 1 diabetes was defined as age at onset ≤40 years, C-peptide negativity and insulin treatment initiated within 1 year of diagnosis. Retinopathy status was assessed from fundus photographs and stereoscopic fundus examinations and graded with the ETDRS scale.

RESULTS

After 30 years of diabetes, the estimated cumulative incidences of CSME were 17% (95% CI 11-26) in age at onset group 0-4 years, 27% (95% CI 23-32) in age at onset group 5-14 years and 34% (95% CI 27-41) in age at onset group 15-40 years (p = 0.002, Gray's test). In a competing risks regression model, adjusted for covariates selected with Bayesian information criteria, age at onset 5-14 years (HR 1.89 [95% CI 1.22-2.91], p = 0.004), and age at onset 15-40 years (HR 3.72 [95% CI 2.35-5.89], p < 0.0001), were significant overall risk factors for CSME (p < 0.0001). Higher ETDRS score (HR 1.04 ([95% CI 1.03-1.05], p < 0.0001), HbA1c (HR 1.12 [95% CI 1.02-1.23], p = 0.016), and total cholesterol (HR 1.19 [95% CI 1.04-1.37], p = 0.013) also increased the risk of CSME.

CONCLUSIONS

Higher age at onset of type 1 diabetes is a significant risk factor for macular oedema. This suggests that ageing may modify the risk of retinopathy in type 1 diabetes.

TNF-alpha levels in tears: a novel biomarker to assess the degree of diabetic retinopathy

We assess the level of tumour necrosis factor alpha (TNF-alpha) in tear fluids and other serum parameters associated with diabetes in different degrees of diabetic retinopathy. We have performed a prospective, nonrandomized, observational study. Study population consisted of 16 healthy subjects (controls) and 32 type 2 diabetic patients: 16 affected by proliferative diabetic retinopathy (PDR) and 16 with nonproliferative retinopathy (NDPR, background/preproliferative). Body mass index, urinary albumin, blood glucose, HbA1c, and tear levels of TNF-alpha were measured in all subjects. The value of glycaemia, microalbuminurea, and Body mass index in diabetic retinopathy groups were higher than those in control group (P < 0.05). Glycemia in NPDR: 6.6 mmol/L (range: 5.8-6.3); in PDR: 6.7 mmol/L (range: 6.1-7.2); in control: 5.7 mmol/L (range: 4.9-6.1); microalbuminurea in NPDR: 10.6 mg/L (range: 5.6-20); in PDR: 25.2 mg/L (range: 17-40); in control: 5.3 mg/L (range: 2.6-10); Body mass index in NPDR: 26 Kg/m(2) (range: 20.3-40); in PDR: 28 Kg/m(2) (range 20.3-52); in control: 21 Kg/m(2) (range 19-26). The TNF-alpha concentrations in tears increase with the severity of pathology and were lower in control group than in diabetic subjects. In the end, the level of TNF-alpha is highly correlated with severity of diabetic retinopathy and with nephropathy. Tear fluid collection may be a useful noninvasive method for the detection of proliferative diabetic retinopathy.

Diabetic retinopathy in sub-Saharan Africa: meeting the challenges of an emerging epidemic

BACKGROUND

Sub-Saharan Africa faces an epidemic of diabetes. Diabetes causes significant morbidity including visual loss from diabetic retinopathy, which is largely preventable. In this resource-poor setting, health systems are poorly organized to deliver chronic care with multiple system involvement. The specific skills and resources needed to manage diabetic retinopathy are scarce. The costs of inaction for individuals, communities and countries are likely to be high.

DISCUSSION

Screening for and treatment of diabetic retinopathy have been shown to be effective, and cost-effective, in resource-rich settings. In sub-Saharan Africa, clinical services for diabetes need to be expanded with the provision of effective, integrated care, including case-finding and management of diabetic retinopathy. This should be underpinned by a high quality evidence base accounting for differences in diabetes types, resources, patients and society in Africa. Research must address the epidemiology of diabetic retinopathy in Africa, strategies for disease detection and management with laser treatment, and include health economic analyses. Models of care tailored to the local geographic and social context are most likely to be cost effective, and should draw on experience and expertise from other continents. Research into diabetic retinopathy in Africa can drive the political agenda for service development and enable informed prioritization of available health funding at a national level. Effective interventions need to be implemented in the near future to avert a large burden of visual loss from diabetic retinopathy in the continent.

SUMMARY

An increase in visual loss from diabetic retinopathy is inevitable as the diabetes epidemic emerges in sub-Saharan Africa. This could be minimized by the provision of case-finding and laser treatment, but how to do this most effectively in the regional context is not known. Research into the epidemiology, case-finding and laser treatment of diabetic retinopathy in sub-Saharan Africa will highlight a poorly met need, as well as guide the development of services for that need as it expands.

Epidemiology of diabetic retinopathy and maculopathy in Africa: a systematic review

AIM

To summarize findings from studies reporting the prevalence and incidence of diabetic retinopathy and diabetic maculopathy in African countries in light of the rising prevalence of diabetes mellitus.

METHODS

Using a predefined search strategy, we systematically searched MEDLINE, EMBASE, Science Citation index and Conference Proceedings Citation index, African Index Medicus and the grey literature database 'OpenSIGLE' for studies published between January 1990 and February 2011. Included studies reported prevalence or incidence of diabetic retinopathy or diabetic maculopathy of subjects with diabetes resident in African countries.

RESULTS

Sixty-two studies from 21 countries were included: three population-based surveys; two cohort studies; five case-control studies; 32 diabetes clinic-based, nine eye clinic-based and 11 other hospital-based surveys. Included studies varied considerably in terms of patient selection, method of assessing the eye and retinopathy classification. In population-based studies, the reported prevalence range in patients with diabetes for diabetic retinopathy was 30.2 to 31.6%, proliferative diabetic retinopathy 0.9 to 1.3%, and any maculopathy 1.2 to 4.5%. In diabetes clinic-based surveys, the reported prevalence range for diabetic retinopathy was 7.0 to 62.4%, proliferative diabetic retinopathy 0 to 6.9%, and any maculopathy 1.2 to 31.1%. No obvious association between prevalence and income level of the country was detected.

CONCLUSIONS

Large, community-based cross-sectional and cohort studies are needed to investigate rates and determinants of prevalence of diabetic retinopathy, incidence and progression in Africa. Consensus is needed on the most appropriate methods of identification and classification of retinopathy for research and clinical practice. Estimates of prevalence of diabetic retinopathy, proliferative diabetic retinopathy and maculopathy are comparable with recent European and American studies.

Prevalence of diabetic retinopathy in Type 2 diabetes in developing and developed countries

BACKGROUND

As the global prevalence of diabetes increases, so will the numbers of people with diabetic retinopathy. Our review aimed to provide a comprehensive picture of available studies of diabetic retinopathy and how prevalence varies around the developed and developing world.

METHODS

A detailed literature search using PubMed was undertaken. The following search term was used: 'diabetic retinopathy AND prevalence'. The titles and abstracts of all publications identified by the search were reviewed and 492 studies were retrieved. Inclusion and exclusion criteria were applied.

RESULTS

A total of 72 articles from 33 countries were included. There were only 26 population-based studies using fundus photography (12 in developing countries), of which only 16 (eight in developing countries) were published since 2000. Prevalence estimates varied from as low as 10% to as high as 61% in persons with known diabetes and from 1.5 to 31% in newly diagnosed diabetes. Across all the studies, the median (interquartile range) prevalence of any diabetic retinopathy in known diabetes was 27.9% (22-37%) and 10.5% (6-16%) in newly diagnosed diabetes. Prevalence of diabetic retinopathy was higher in developing countries.

CONCLUSION

Significant gaps exist in that reliable population-based data from developing nations and indigenous populations in particular are lacking. Major differences in study characteristics and methodologies make comparisons very difficult. More research is required and study methodologies must be better standardized. This will provide important information for prevention and treatment strategies.

Prevalence of diabetic retinopathy in Norway: report from a screening study

PURPOSE

The purpose of the present study was to investigate the prevalence of diabetic retinopathy (DR) in Norway and adherence to the Norwegian Guidelines for screening for diabetic eye disease.

METHODS

Two hundred and ninety-nine people with diabetes were randomly recruited from the patient lists of randomly selected general practitioners from three different regions in Norway. Retinopathy was evaluated from retinal photographs after dilation of the pupils using a red-free digital camera and visual acuity was measured using the Snellen chart. The patients were interviewed about their ophthalmological and general diabetes control, duration and type of diabetes and medical treatment.

RESULTS

The prevalence of any DR was 28%, 66% for type 1 and 24% for type 2 diabetes. The prevalence of proliferative retinopathy was 38% in type 1 and 1.5% in type 2 diabetes. Two patients (one type 1 and one insulin-treated type 2) were visually impaired (visual acuity 0.3 or worse in the better eye) because of proliferative DR. Twenty-six per cent of the patients had never been to an eye examination, and only 69% attended routine eye examinations. Patients who did not attend regular eye screenings were mostly people with type 2 diabetes.

CONCLUSION

The prevalence of DR was higher than previously reported in Norway. Screening for DR did not follow guidelines in a considerable proportion of the patients with type 2 diabetes. There is place for improvement in the implementation of guidelines for screening for DR for people with type 2 diabetes in Norway.

Increased IL-6 levels are not related to NF-κB or HIF-1α transcription factors activity in the vitreous of proliferative diabetic retinopathy

PURPOSE

The purpose was to assess the activity of nuclear factor (NF)-κB and hypoxia inducible factor (HIF)-1α transcription factors and the expression levels of inflammation markers [interleukin (IL)-6 and IL-8] in the vitreous of patients suffering from proliferative diabetic retinopathy (PDR) scheduled for elective vitreous surgery in a single academic-based retina practice in a prospective clinical study.

METHODS

Twenty-seven patients with PDR were enrolled in the study. The severity of retinopathy was classified (0, 1, 2, 3, 4) and the activity of neovascularization was graded (0, 1, 2, 3, 4) by the surgeon intraoperatively. Samples of the vitreous were collected during surgery, and the activity of NF-κB and HIF-1α transcription factors and the expression levels of IL-6 and IL-8 were measured.

RESULTS

The majority of samples fell into the retinopathy class 3 (n = 12) or 4 (n = 13). The level of IL-6 increased from 68.9 ± 46.8 pg/ml to 102.7 ± 94.1 pg/ml, and IL-8 increased from 165.1 ± 136.0 pg/ml to 521.0 ± 870.9 pg/ml (mean ± S.D., nonsignificant change: normality test followed with Mann-Whitney Rank Sum Test). According to the neovascularization activity, the samples fell into grade 1 (n = 7), 2 (n = 12) or 3 (n = 7). In IL-6, there was a statistically significant increase (P < .05) from grade 2 to 3: 58.6 ± 40.3 pg/ml and 158.4 ± 102.5 pg/ml, respectively (Kruskal-Wallis One-Way Analysis of Variance on Ranks followed with Dunn's Method). The level of IL-8 was as follows: in grade 1: 118.0 ± 62.4 pg/ml, in grade 2: 192.3 ± 127.1 pg/ml and in grade 3: 884.3 ± 1161.0 pg/ml (statistically nonsignificant change). There was a statistically significant linear regression between IL-6 and IL-8 (P < .001): IL-6 = 51.88 pg/ml + (0.092*IL-8), r = 0.772. Increased activity of the NF-κB and HIF-1α transcription factors was not observed.

CONCLUSION

Interleukin-6 is a candidate to indicate activity of neovascularization process in PDR. It might be a new molecular therapeutic target to regulate innate immunity response in vitreous.

Prevalence of chronic complications in korean patients with type 2 diabetes mellitus based on the korean national diabetes program

BACKGROUND

The Korean National Diabetes Program (KNDP) cohort study is performing an ongoing large-scale prospective multicenter investigation to discover the pathogenesis of type 2 diabetes in Korean patients. This study was performed to examine the prevalence of chronic complications in patients with type 2 diabetes among those registered in the KNDP cohort within the past 4 years.

METHODS

This study was performed between June 2006 and September 2009 at 13 university hospitals and included 4,265 KNDP cohort participants. Among the participants, the crude prevalence of microvascular and macrovascular diseases of those checked for diabetes-related complications was determined, and the adjusted standard prevalence and standardization of the general population prevalence ratio (SPR) was estimated based on the 2005 Korean National Health and Nutrition Examination Survey (KNHANES) population demographics.

RESULTS

Among the KNDP registrants, 43.2% had hypertension, 34.8% had dyslipidemia, 10.8% had macrovascular disease, and 16.7% had microvascular disease. The SPR of the KNDP registrants was significantly higher than that of the KNHANES subjects after adjusting for demographics in the KNHANES 2005 population. However, with the exception of cardiovascular disease in females, the standardized prevalence for the most complicated items in the survey was significantly higher than that in the KNHANES subjects.

CONCLUSION

The prevalence of macrovascular disease and peripheral vascular disease were significantly higher in Korean patients with type 2 diabetes than in the normal population. However, no significant difference was noted in the prevalence of cardiovascular disease in females.

Protection from retinopathy and other complications in patients with type 1 diabetes of extreme duration: the joslin 50-year medalist study

OBJECTIVE

To assess complication prevalence and identify protective factors in patients with diabetes duration of ≥50 years. Characterization of a complication-free subgroup in this cohort would suggest that some individuals are protected from diabetes complications and allow identification of endogenous protective factors.

RESEARCH DESIGN AND METHODS

Cross-sectional, observational study of 351 U.S. residents who have survived with type 1 diabetes for ≥50 years (Medalists). Retinopathy, nephropathy, neuropathy, and cardiovascular disease were assessed in relation to HbA(1c), lipids, and advanced glycation end products (AGEs). Retrospective chart review provided longitudinal ophthalmic data for a subgroup.

RESULTS

A high proportion of Medalists remain free from proliferative diabetic retinopathy (PDR) (42.6%), nephropathy (86.9%), neuropathy (39.4%), or cardiovascular disease (51.5%). Current and longitudinal (the past 15 years) glycemic control were unrelated to complications. Subjects with high plasma carboxyethyl-lysine and pentosidine were 7.2-fold more likely to have any complication. Of Medalists without PDR, 96% with no retinopathy progression over the first 17 years of follow-up did not experience retinopathy worsening thereafter.

CONCLUSIONS

The Medalist population is likely enriched for protective factors against complications. These factors might prove useful to the general population with diabetes if they can be used to induce protection against long-term complications. Specific AGE combinations were strongly associated with complications, indicating a link between AGE formation or processing with development of diabetic vasculopathy.

Prevalence and healthcare costs of diabetic retinopathy: a population-based register study in Sweden

AIMS/HYPOTHESIS

The aim of the present study was to estimate the prevalence and healthcare costs of diabetic retinopathy (DR).

METHODS

This population-based study included all residents (n = 251,386) in the catchment area of the eye clinic of Linköping University Hospital, Sweden. Among patients with diabetes (n = 12,026), those with and without DR were identified through register data from both the Care Data Warehouse in Ostergötland, an administrative healthcare register, and the Swedish National Diabetes Register. Healthcare cost data were elicited by record linkage of these two registers to data for the year 2008 in the Cost Per Patient Database developed by Ostergötland County Council.

RESULTS

The prevalence of any DR was 41.8% (95% CI 38.9-44.6) for patients with type 1 diabetes and 27.9% (27.1-28.7) for patients with type 2 diabetes. Sight-threatening DR was present in 12.1% (10.2-14.0) and 5.0% (4.6-5.4) of the type 1 and type 2 diabetes populations respectively. The annual average healthcare cost of any DR was euro72 (euro53-91). Stratified into background retinopathy, proliferative DR, maculopathy, and the last two conditions combined, the costs were euro26 (euro10-42), euro257 (euro155-359), euro216 (euro113-318) and euro433 (euro232-635) respectively. The annual cost for DR was euro106,000 per 100,000 inhabitants.

CONCLUSIONS

This study presents new information on the prevalence and costs of DR. Approximately one-third of patients with diabetes have some form of DR. Average healthcare costs increase considerably with the severity of DR, which suggests that preventing progression of DR may lower healthcare costs.

The potential of digital monochrome images versus colour slides in telescreening for diabetic retinopathy

We explored the potential of digital monochrome images as an alternative to colour slides in screening for diabetic retinopathy. Twenty-eight patients with diabetes were recruited for the study and 20 actually participated. Using a fundus camera (Nikon 505AF) one set of three digital images and one set of three colour slides were taken per eye. Two independent ophthalmologists graded the colour slides and the digital images for diabetic retinopathy. The ophthalmologists spent about two minutes grading each set of images, suggesting that specialists could potentially screen a large number of patients. The agreement between the two screening methods was 0.95 and 0.89, with respect to disease or no disease. The agreement (kappa) between the two ophthalmologists for grade of retinopathy was 0.47 when colour slides were employed and 0.61 when digital monochrome images were employed. The results indicate that digital red-free monochrome images represent a superior screening tool for diabetic retinopathy. Tele-screening may be beneficial when patients have to travel substantial distances to visit an ophthalmologist.

[Epidemiology of diabetic retinopathy in Lebanon]

AIMS

To assess the prevalence of diabetic retinopathy, evaluate risk factors underlying its development, and assess the epidemiological characteristics of documented diabetes in the Lebanese population.

PATIENTS AND METHOD

The population-based study was conducted in three regions in Lebanon from January 2nd 2000 until June 30th 2000. The study group comprised 112 known diabetic patients who had previously been identified among 4,063 randomly selected individuals. All known diabetic patients underwent an interview, a physical examination, and a thorough retinal examination that included evaluation for the absence or presence of diabetic retinopathy. Retinal examination was performed by an ophthalmologist using direct and indirect ophthalmoscopy through dilated pupils. Several risk factors were then evaluated in order to delineate those related to occurrence of diabetic retinopathy.

RESULTS

The prevalence of known diabetes was 2.95%. Of the 120 known diabetic patients, 112 accepted to be examined. The sex ratio (m:f) was 1.43, the mean patient age was 60.98 years, the mean age at onset of diabetes was 51.75 years, and the mean duration of diabetes was 9.19 years. Type 1 diabetes was found in 1.8% of the patients, whereas 98.2% had type 2 diabetes. Diabetic retinopathy was detected in 19 patients (16.96%). Duration of diabetes, frequency of fundoscopic surveillance, and altered vision were found to be significantly related to the occurrence of diabetic retinopathy.

CONCLUSION

In our study, diabetic retinopathy was found in 16.96% of known diabetic patients, a lower rate than in most of other countries. Most of the diabetic patients (84.82%) were aware that diabetes causes ocular disease, yet only a few (17.85%) were under regular fundoscopic surveillance.

The relationships between risk factors and the distribution of retinopathy lesions in type 2 diabetes

PURPOSE

Previous studies have shown that the progression of diabetic retinopathy to vision-threatening lesions may be related to the development of retinopathy lesions in specific retinal areas. The purpose of the present study was to examine whether the occurrence of retinopathy in these retinal areas is related to known risk factors for progression of retinopathy in type 2 diabetes.

METHODS

A total of 377 randomly selected patients with type 2 diabetes underwent examinations which included measurement of blood pressure, haemoglobin A1c and cholesterol, and a full eye examination including fundus photography. The fundus photographs were digitized and a computer-assisted technique was used to quantify retinopathy lesions in the macular area, around the vascular arcades and in the retinal periphery. Only the number of microaneurysms/haemorrhages was sufficient for statistical analysis.

RESULTS

Patients with retinopathy had significantly longer diabetes duration, and higher blood pressure and HgbA1c than patients without retinopathy. However, among the patients with retinopathy there was no correlation between these risk factors and the overall number of microaneurysms/haemorrhages or the number of these lesions in the local areas of the fundus studied.

CONCLUSIONS

The localized distribution of retinopathy lesions does not correlate with known risk factors and background factors for the development of diabetic retinopathy in the early stages of the disease. Future improvements of grading systems for diabetic retinopathy should focus on a quantification of the overall number and dynamics of retinopathy lesions in the early stages of retinopathy and the regional distribution and dynamics of lesions in more advanced stages of retinopathy.

Epidemiology of diabetic retinopathy and macular oedema: a systematic review

AIMS

To systematically review the literature on the prevalence and incidence of diabetic retinopathy (DR) and macular oedema (MO).

METHODS

A search of the bibliographic databases (Medline, Embase, CINAHL) was conducted up to October 2001. Selected relevant studies were scrutinized and included in the review.

RESULTS

A total of 359 studies were included. The studies were reported in nearly 100 different journals and in over 50 countries. The majority of the studies were US-based, with large studies such as the Wisconsin Epidemiologic Study of Diabetic Retinopathy dominating the literature. The studies were quite dated and highly heterogeneous in nature in terms of patient selection with variable inclusion criteria (age range, gender, diabetes duration and type, ethnicity, comorbidity, and DR status, assessment, and classification).

CONCLUSIONS

There are inconsistencies between epidemiological studies, and differences in study methods may contribute to conflicting reports of prevalence and incidence of DR and MO in diabetic populations. As new therapies for DR and its associated complications emerge, the need to capture and monitor new epidemiological data becomes increasingly important to be able to assess the impact and effectiveness of these therapies. Robust, longitudinal capture of patient data is, therefore, essential to evaluate the impact of current practice on the epidemiology of diabetic eye complications.

The prevalence of retinopathy in an unselected population of type 2 diabetes patients from Arhus County, Denmark

PURPOSE

To determine the prevalence of diabetic retinopathy and the causes of visual impairment in an unselected population of type 2 diabetes patients, and to describe the risk factors for developing diabetic retinopathy in this population.

METHODS

A total of 10 851 type 2 diabetes patients were identified in the county of Arhus. A representative sample of 378 patients underwent a routine ocular examination, including fundus photography. Blood pressure and serum haemoglobin A1c, total cholesterol, high density lipoprotein cholesterol, triglyceride and apolipoprotein a were measured.

RESULTS

The prevalence of diabetic retinopathy in the type 2 diabetes population was 31.5%. In all, 2.9% had proliferative diabetic retinopathy and 5.3% had clinically significant macular oedema. Of the latter, 8/20 (40%) were newly identified and had not yet been laser-treated. There was a positive correlation between severity of retinopathy and duration of diabetes, HbA(1c), systolic blood pressure and treatment with insulin. None of the patients had social blindness (visual acuity < 0.1), but 15/378 (4.0%) had developed visual impairment (VA < 0.3).

CONCLUSION

The prevalence of diabetic retinopathy and visual impairment in this unselected type 2 diabetes population was lower than anticipated from the existing literature, and causes other than diabetic retinopathy contributed significantly to the occurrence of visual loss. A substantial number of the patients with vision-threatening diabetic maculopathy had not been referred for timely photocoagulation treatment.

Incidence of sight-threatening retinopathy in patients with type 2 diabetes in the Liverpool Diabetic Eye Study: a cohort study

BACKGROUND

Incidence data on which to base targets and protocols for screening for sight-threatening diabetic retinopathy are few. We aimed to investigate yearly and cumulative incidence of any retinopathy, maculopathy, and sight-threatening diabetic retinopathy in patients with type 2 diabetes in an established systematic programme and to calculate optimum screening intervals according to retinopathy grade at baseline.

METHODS

We investigated all patients with type 2 diabetes registered with enrolled general practices (except those who were attending an ophthalmologist) who had retinopathy data available at baseline and at least one further screening event. To screen patients, we used non-stereoscopic three-field mydriatic photography and modified Wisconsin grading. Sight-threatening diabetic retinopathy was defined as moderate preproliferative retinopathy or worse, or clinically significant maculopathy in either or both eyes.

FINDINGS

Results were obtained from 20 570 screening events. Yearly incidence of sight-threatening diabetic retinopathy in patients without retinopathy at baseline was 0.3% (95% CI 0.1-0.5) in the first year, rising to 1.8% (1.2-2.5) in the fifth year; cumulative incidence at 5 years was 3.9% (2.8-5.0). Rates of progression to sight-threatening diabetic retinopathy in year 1 by baseline status were: background 5.0% (3.5-6.5), and mild preproliferative 15% (10.2-19.8). For a 95% probability of remaining free of sight-threatening diabetic retinopathy, mean screening intervals by baseline status were: no retinopathy 5.4 years (95% CI 4.7-6.3), background 1.0 years (0.7-1.3), and mild preproliferative 0.3 years (0.2-0.5).

INTERPRETATION

A 3-year screening interval could be safely adopted for patients with no retinopathy, but yearly or more frequent screening is needed for patients with higher grades of retinopathy.

Prevalence of diabetic eye disease in patients entering a systematic primary care-based eye screening programme

AIMS

Large-scale, baseline prevalence measurements in a population at the institution of systematic retinal screening are currently unavailable. We report the prevalence of all grades of retinopathy at entry into a systematic primary care-based diabetic eye screening programme.

METHODS

Primary care-based photographic screening utilizing mydriasis and three-field non-stereoscopic photography for all patients with diabetes (except those under continuing care of an ophthalmologist) in Liverpool. Sight-threatening diabetic eye disease (STED) was defined as any of: moderate preproliferative retinopathy or worse, circinate maculopathy or exudates within one disc diameter of the centre of fovea.

RESULTS

Type 1 diabetes mellitus (DM) (n = 831): baseline prevalence (95% confidence interval (CI)) of any retinopathy, proliferative diabetic retinopathy (PDR) and STED was 45.7% (42.3-49.1), 3.7% (2.4-5.0) and 16.4% (13.9-18.9), respectively. Presence of STED was associated with increased disease duration (odds ratio (OR) 1.09 per year; P < 0.0001) and higher in men (OR 2.15; P = 0.001). Type 2 DM (n = 7231): baseline prevalence (95% CI) of any retinopathy, PDR and STED was 25.3% (24.3-26.3), 0.5% (0.3-0.7) and 6.0% (5.5-6.5), respectively. Presence of STED was associated with longer time since diagnosis of DM (OR 1.03; P < 0.0001) and insulin use (OR 2.46; P < 0.0001).

CONCLUSION

This study provides baseline information for health providers on prevalence of all grades of retinopathy and STED in a large population at the establishment of systematic screening. Baseline prevalence of STED was high and highest in patients with a longer disease duration in both Type 1 and Type 2 DM.

Occurrence and predictors of retinopathy and visual acuity in Type 2 diabetic patients and control subjects. 10-year follow-up from the diagnosis

The evolution of visual acuity and retinopathy and their risk factors in patients with newly diagnosed type 2 diabetes and in control subjects. A 10-year prospective study consisting of a representative group of 133 (70 men, 63 women) newly diagnosed type 2 diabetic patients diagnosed at health centers between 1979 and 1981 and 144 (62 men, 82 women) non-diabetic control subjects recruited from the population register. The frequency of retinopathy was determined by grading of 45 degrees fundus photographs at baseline and after 5 and 10 years. By the 10-year follow-up the diabetic patients had lower visual acuity than the control subjects. The impairment of the visual acuity correlated inversely to HbA(1C) value of the 5-year examination. The frequency of retinopathy in type 2 diabetic patients increased sharply after 5 years and at 10-year 55% of diabetic patients had signs of retinopathy. The frequency of retinopathy in the control subjects was low, but detectable. In the diabetic patients poor glycemic control was the most important predictive factor for the development of retinopathy. In the control subjects blood pressure levels were higher and microalbuminuria more common in those with than in those without retinopathy. The visual acuity deteriorated and the frequency of retinopathy increased in newly diagnosed type 2 diabetic patients with duration of disease and poor glycemic control. Interestingly, higher blood pressure levels and microalbuminuria predicted retinopathy in control subjects.

The frequency and severity of retinopathy are related to HbA1c values after, but not at, the diagnosis of NIDDM

OBJECTIVES

To examine the relationship between previous glycaemic exposure and prevalence of retinopathy 8 years after diagnosis of diabetes in 58 islet cell antibodies (ICA)-negative noninsulin-dependent diabetes mellitus (NIDDM) patients and in a group of 14 ICA-positive 'NIDDM' and insulin-dependent diabetes mellitus (IDDM) patients.

DESIGN AND METHODS

The Wisconsin retinopathy scale was used to assess the retinopathy which was graded into mild, moderate and severe nonproliferative diabetic retinopathy (NPDR), or proliferative retinopathy (PDR). The frequency and severity of retinopathy was related to HbA1c levels at diagnosis, and 3 and 5 years later.

RESULTS

Thirty of the 58 ICA-negative NIDDM patients (52%) but only 2 of the 14 ICA-positive 'NIDDM' or IDDM patients (14%) had mild-moderate-severe NPDR 8 years after diagnosis (P = 0.02). None had PDR. Retinopathy 8 years after diagnosis in NIDDM (= 58 ICA-negative patients) was correlated with the degree of glycaemic control (HbA1c levels) at 3 and 5 years after diagnosis, but not to HbA1c levels at diagnosis. The relative risk for a higher average HbA1c (per percentage) at 3 and 5 years was 1.56 for any retinopathy vs. no retinopathy (95% confidence interval 1.1-2.2; P = 0.01) and 1.68 for moderate to severe NPDR in comparison with no DR and mild NPDR (95% confidence interval 1.0-2.8; P = 0.04).

CONCLUSIONS

Retinopathy after 8 years of diabetes in NIDDM patients was associated with impaired glycaemic control during previous years but not with glycaemic control at baseline. Good glycaemic control may prevent retinopathy in patients with NIDDM.

Prevalence and risk factors for diabetic retinopathy among Omani diabetics

AIMS

To study the prevalence of diabetic retinopathy in a population of patients attending a diabetic clinic and to evaluate the medical risk factors underlying its development.

METHODS

500 randomly selected diabetic patients attending the diabetes clinic in Al Buraimi hospital were referred to the ophthalmology department where they were fully evaluated for the absence or presence of retinopathy. Any retinopathy present was graded as mild non-proliferative retinopathy (NPR), moderate-severe NPR, and proliferative retinopathy. Several risk factors were then evaluated in order to delineate those related to occurrence of retinopathy in general as well as to the different grades of retinopathy in particular.

RESULTS

Diabetic retinopathy was detected in 212 patients (42.4%), with mild NPR present in 128 patient (25.6% of the total population), moderate-severe NPR in 20 patients (4%), and proliferative diabetic retinopathy present in 64 patients (12.8%). Factors significantly related to occurrence of retinopathy were age of the patient, duration of diabetes, presence of ischaemic heart disease, presence of hypertension, a high fasting capillary glucose level as well as elevated serum levels of urea, creatinine, cholesterol, and triglycerides. After adjustment for covariates, it was found that duration of diabetes was the only risk factor associated with mild NPR, while high diastolic blood pressure and high levels of serum creatinine, cholesterol, and triglycerides were significantly associated with the occurrence of proliferative retinopathy.

CONCLUSIONS

In addition to glycaemic control, lowering of blood lipids as well as diastolic blood pressure (in hypertensive patients) may be effective in lowering the incidence of retinopathy in compromised patients.

Incidence of blindness and visual impairment in diabetic patients participating in an ophthalmological control and screening programme

We studied the incidence of blindness and visual impairment in patients who were enrolled in a photographic control- and screening program for diabetic retinopathy. The study cohort consisted of 2133 patients examined between January 1990 and December 1992 and followed until October 1st 1995. The occurrence of blindness (visual acuity < or = 0.1) and moderate visual impairment (visual acuity 0.2-0.4) was assessed. The Wisconsin scale was used to grade retinopathy. The mean HbA1c value for the last 8 years was used to represent long-term glycaemic control. Average follow-up time was 2.9 years. Seven patients were blind and 24 had visual impairment caused by retinopathy at the entry of the study. Six patients went blind due to retinopathy during the study period, corresponding to an incidence of 1.0 per 1000 person-years (95% confidence interval 0.4-2.1), and 28 became visually impaired, corresponding to an incidence of 4.6 per 1000 person-years (95% confidence interval 3.0-6.6). Multivariate analysis showed a statistically significant association between blindness/visual impairment and old age, long duration of diabetes, and poor glycaemic control. HbA1c values in the highest quartile, i.e. > or = 8.5%, were associated with a 65% increase in risk of blindness/visual impairment (95% confidence interval 14-130%). Retinopathy was the major cause of blindness and visual impairment in patients with diabetes. The study revealed a low incidence of blindness, which is in line with recent reports. Control of hyperglycaemia may be of value for the prevention of visual loss.

Progression of retinopathy is related to glycaemic control even in patients with mild diabetes mellitus

To study the progression of retinopathy in patients with mild diabetes mellitus, we examined, in a cohort study, 347 patients treated with diet alone at baseline. The patients participated in an ophthalmological screening and control programme, and diet-treated patients who were examined between January 1990 and July 1992 were included in the study and followed until October 1995. Mean follow-up was 3.4 +/- 1.1 years. The alternative classification of the Wisconsin study was used to classify retinopathy, and the mean HbA1c values for the study period, to estimate the level of glycaemic control. At baseline, 314 of the patients (90.5%) had no retinopathy, and 33 (9.5%) had mild non-proliferative diabetic retinopathy. In 296 patients there was no retinopathy progression, in 27 patients there was progression by 1 level in the retinopathy scale, and in 24 patients by 2 levels or more. In 2 patients there was progression to proliferative diabetic retinopathy. The mean HbA1c (%) was 6.5 +/- 1.3. Higher HbA1c correlated to increased progression (r = 0.16; p = 0.005), and in a multivariate analysis, HbA1c remained associated with a progression of retinopathy by 2 levels or more, with a relative risk of 1.4 per percent increase in HbA1c (95% CI 1.1-2.0; p = 0.02). Furthermore, the presence of any retinopathy at baseline was associated with progression with a relative risk of 1.7 (95% confidence interval 1.1-2.8; (p = 0.02). These data indicate that even slightly elevated levels of HbA1c might be associated with a risk of retinopathy progression.