Blood pressure and retinopathy in type I diabetes

Systemic Predictors of Diabetic Retinopathy and Diabetic Macular Edema in an Adult Veteran Population

Purpose

To investigate the influence of systemic and serum measures and hypoglycemic medications on the initial presentation and ongoing development of diabetic retinopathy (DR) and diabetic macular edema (DME).

Design

Using Veterans Affairs electronic health records, we identified patients with a diabetes mellitus diagnosis and at least one eye examination between 1997 and 2010. After adjusting for sociodemographic factors, we used multivariable Cox regression models to evaluate the association of hemoglobin A1c (HbA1c) levels, blood pressure, albuminuria, blood urea nitrogen (BUN), and prescribed medications with the subsequent diagnosis of 1) any diabetic eye disease (defined for this analysis as DR and/or DME, 2) diabetic retinopathy, and 3) diabetic macular edema.

Results

Of 4089 diabetic Veteran patients, 821 (20%) were subsequently diagnosed with diabetic retinopathy and 88 (2%) had macular edema. Patients were more likely to receive a diabetic retinopathy diagnosis if they presented with HbA1c > 8.5 (HR=2.66, 95% CI 1.88-3.77, p<0.01), systolic blood pressure > 140 mmHg (HR=1.45, 95% CI 1.26-1.66, p<0.01), blood urea nitrogen (BUN) > 35 mg/dL (HR=2.17, 95% CI 1.60-2.93, p<0.01), and/or used insulin (HR=2.04, 95% CI 1.74-2.40, p<0.01). Patients were more likely to be diagnosed with diabetic macular edema if they had systolic blood pressure > 140 mmHg (HR=2.00, CI 1.29-3.08, p<0.01) and/or used insulin (HR=2.48, CI 1.53-4.03, p<0.01).

Conclusion

Markers of systemic health may be useful predictors for incident diabetic retinopathy or diabetic macular edema, evaluated collectively in Veteran patients. Higher HbA1c levels, systolic blood pressure, BUN levels, and insulin use (suggestive of more severe and/or long-standing diabetes) appear to be highly associated with the development of diabetic eye disease, and, in particular, diabetic retinopathy.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Elucidating glial responses to products of diabetes-associated systemic dyshomeostasis

Diabetic retinopathy (DR) is a leading cause of blindness in working age adults. DR has non-proliferative stages, characterized in part by retinal neuroinflammation and ischemia, and proliferative stages, characterized by retinal angiogenesis. Several systemic factors, including poor glycemic control, hypertension, and hyperlipidemia, increase the risk of DR progression to vision-threatening stages. Identification of cellular or molecular targets in early DR events could allow more prompt interventions pre-empting DR progression to vision-threatening stages. Glia mediate homeostasis and repair. They contribute to immune surveillance and defense, cytokine and growth factor production and secretion, ion and neurotransmitter balance, neuroprotection, and, potentially, regeneration. Therefore, it is likely that glia orchestrate events throughout the development and progression of retinopathy. Understanding glial responses to products of diabetes-associated systemic dyshomeostasis may reveal novel insights into the pathophysiology of DR and guide the development of novel therapies for this potentially blinding condition. In this article, first, we review normal glial functions and their putative roles in the development of DR. We then describe glial transcriptome alterations in response to systemic circulating factors that are upregulated in patients with diabetes and diabetes-related comorbidities; namely glucose in hyperglycemia, angiotensin II in hypertension, and the free fatty acid palmitic acid in hyperlipidemia. Finally, we discuss potential benefits and challenges associated with studying glia as targets of DR therapeutic interventions. In vitro stimulation of glia with glucose, angiotensin II and palmitic acid suggests that: 1) astrocytes may be more responsive than other glia to these products of systemic dyshomeostasis; 2) the effects of hyperglycemia on glia are likely to be largely osmotic; 3) fatty acid accumulation may compound DR pathophysiology by promoting predominantly proinflammatory and proangiogenic transcriptional alterations of macro and microglia; and 4) cell-targeted therapies may offer safer and more effective avenues for DR treatment as they may circumvent the complication of pleiotropism in retinal cell responses. Although several molecules previously implicated in DR pathophysiology are validated in this review, some less explored molecules emerge as potential therapeutic targets. Whereas much is known regarding glial cell activation, future studies characterizing the role of glia in DR and how their activation is regulated and sustained (independently or as part of retinal cell networks) may help elucidate mechanisms of DR pathogenesis and identify novel drug targets for this blinding disease.

Blood pressure control and its associated factors in patients with hypertension and type 2 diabetes

In this retrospective study, the medical records of hypertensive patients with type 2 diabetes attending two major hospitals were reviewed to find the factors associated with poor blood pressure control in patients who have diabetes as a comorbid disease with hypertension. Binary regression analysis was conducted to find the factors independently associated with BP control. A total of 522 participants were included in the study. Most of the participants had uncontrolled hypertension (63.4%) and uncontrolled type 2 diabetes (51.3%). Regression results revealed that having retinopathy (OR=1.468 (95% CI: 1.020-2.113), p&lt;0.05), and not receiving dipeptidyl-peptidase 4 (DPP4) inhibitors were independently associated with uncontrolled BP (OR=0.633 (95%CI 0.423-0.946), p&lt;0.05). Therefore, greater efforts should be exerted to improve BP control in hypertensive patients with type 2 diabetes, particularly in those suffering from retinopathy.

Studies of the retinal microcirculation using human donor eyes and high-resolution clinical imaging: Insights gained to guide future research in diabetic retinopathy

The microcirculation plays a key role in delivering oxygen to and removing metabolic wastes from energy-intensive retinal neurons. Microvascular changes are a hallmark feature of diabetic retinopathy (DR), a major cause of irreversible vision loss globally. Early investigators have performed landmark studies characterising the pathologic manifestations of DR. Previous works have collectively informed us of the clinical stages of DR and the retinal manifestations associated with devastating vision loss. Since these reports, major advancements in histologic techniques coupled with three-dimensional image processing has facilitated a deeper understanding of the structural characteristics in the healthy and diseased retinal circulation. Furthermore, breakthroughs in high-resolution retinal imaging have facilitated clinical translation of histologic knowledge to detect and monitor progression of microcirculatory disturbances with greater precision. Isolated perfusion techniques have been applied to human donor eyes to further our understanding of the cytoarchitectural characteristics of the normal human retinal circulation as well as provide novel insights into the pathophysiology of DR. Histology has been used to validate emerging in vivo retinal imaging techniques such as optical coherence tomography angiography. This report provides an overview of our research on the human retinal microcirculation in the context of the current ophthalmic literature. We commence by proposing a standardised histologic lexicon for characterising the human retinal microcirculation and subsequently discuss the pathophysiologic mechanisms underlying key manifestations of DR, with a focus on microaneurysms and retinal ischaemia. The advantages and limitations of current retinal imaging modalities as determined using histologic validation are also presented. We conclude with an overview of the implications of our research and provide a perspective on future directions in DR research.

Imaging Modalities Employed in Diabetic Retinopathy Screening: A Review and Meta-Analysis

INTRODUCTION

Urbanization has caused dramatic changes in lifestyle, and these rapid transitions have led to an increased risk of noncommunicable diseases, such as type 2 diabetes. In terms of cost-effectiveness, screening for diabetic retinopathy is a critical aspect in diabetes management. The aim of this study was to review the imaging modalities employed for retinal examination in diabetic retinopathy screening.

METHODS

The PubMed and Web of Science databases were the main sources used to investigate the medical literature. An extensive search was performed to identify relevant articles concerning "imaging", "diabetic retinopathy" and "screening" up to 1 June 2021. Imaging techniques were divided into the following: (i) mydriatic fundus photography, (ii) non-mydriatic fundus photography, (iii) smartphone-based imaging, and (iv) ultrawide-field imaging. A meta-analysis was performed to analyze the performance and technical failure rate of each method.

RESULTS

The technical failure rates for mydriatic and non-mydriatic digital fundus photography, smartphone-based and ultrawide-field imaging were 3.4% (95% CI: 2.3-4.6%), 12.1% (95% CI: 5.4-18.7%), 5.3% (95% CI: 1.5-9.0%) and 2.2% (95% CI: 0.3-4.0%), respectively. The rate was significantly different between all analyzed techniques (p < 0.001), and the overall failure rate was 6.6% (4.9-8.3%; I2 = 97.2%). The publication bias factor for smartphone-based imaging was significantly higher than for mydriatic digital fundus photography and non-mydriatic digital fundus photography (b = -8.61, b = -2.59 and b = -7.03, respectively; p < 0.001). Ultrawide-field imaging studies were excluded from the final sensitivity/specificity analysis, as the total number of patients included was too small.

CONCLUSIONS

Regardless of the type of the device used, retinal photographs should be taken on eyes with dilated pupils, unless contraindicated, as this setting decreases the rate of ungradable images. Smartphone-based and ultrawide-field imaging may become potential alternative methods for optimized DR screening; however, there is not yet enough evidence for these techniques to displace mydriatic fundus photography.

Update on Screening for Sight-Threatening Diabetic Retinopathy

PURPOSE

The aim of this article was to describe recent advances in the use of new technology in diabetic retinopathy screening by looking at studies that assessed the effectiveness and cost-effectiveness of these technologies.

METHODS

The author conducts an ongoing search for articles relating to screening or management of diabetic retinopathy utilising Zetoc with keywords and contents page lists from relevant journals.

RESULTS

The areas discussed in this article are reference standards, alternatives to digital photography, area of retina covered by the screening method, size of the device and hand-held cameras, mydriasis versus non-mydriasis or a combination, measurement of distance visual acuity, grading of images, use of automated grading analysis and cost-effectiveness of the new technologies.

CONCLUSIONS

There have been many recent advances in technology that may be adopted in the future by screening programmes for sight-threatening diabetic retinopathy but each device will need to demonstrate effectiveness and cost-effectiveness before more widespread adoption.

Diabetic vitrectomy in a large type 1 diabetes patient population: long-term incidence and risk factors

PURPOSE

Diabetic vitrectomy represents an end-point of diabetic retinopathy progression. This study was designed to estimate long-term incidence of diabetic vitrectomy and associated risk factors.

METHODS

Retrospective review of prospectively collected data from a large diabetes centre between 1996 and 2010. Surgical history was obtained from The Danish National Patient Register.

RESULTS

The population consisted of 3980 patients with type 1 diabetes. Median follow-up was 10.0 years. In total, 106 patients underwent diabetic vitrectomy in the observation period. Surgery indications were nonclearing vitreous haemorrhage (43%) or tractional retinal detachment (57%). The cumulative incidence rates of diabetic vitrectomy were 1.6% after 5 years and 2.9% after 10 years. When excluding patients with no or mild diabetic retinopathy, the corresponding rates were higher; 3.7% and 6.4%, respectively (p < 0.001, log-rank test). The risk of reaching diabetic vitrectomy increased in patients experiencing glycosylated haemoglobin A1c > 75 mmol/mol in the observation period (p < 0.001, hazard ratio: 3.9, Cox regression analysis). Systolic blood pressure ≥ 140 mmHg, diastolic blood pressure ≥ 90 mmHg, diabetes duration, age, gender and nephropathy were not associated with an increased risk of reaching diabetic vitrectomy (p > 0.05 for all variables).

CONCLUSIONS

Diabetic vitrectomy is rarely required in a type 1 diabetes population with varying degrees of retinopathy, but the risk increases markedly with poor metabolic control.

Intraocular surgery in a large diabetes patient population: risk factors and surgical results

The prevalence of diabetes is on the increase in developed countries. Accordingly, the prevention and treatment of vision-threatening diabetic eye complications is assuming greater importance. The overall aim of this thesis is to analyse risk factors for intraocular surgery in a large diabetes population and to report surgical results. The specific objectives are to (1) estimate the incidence of diabetic vitrectomy and analyse risk factors (Study I), (2) report long-term results, prognostic factors and incidence of cataract surgery after diabetic vitrectomy (Study II), (3) report results and prognostic factors after cataract surgery in diabetes patients (Study III) and (4) analyse risk factors for diabetic papillopathy with emphasis on metabolic control variability (Study IV). All studies are based on a close-to-complete national surgery register and a large, closely followed diabetic retinopathy screening population. Study I (cohort study, 3980 type 1 diabetes patients) illustrates that diabetic vitrectomy is rarely required in a diabetes patient population with varying degrees of diabetic retinopathy. The risk of reaching diabetic vitrectomy increases fourfold with poor metabolic control, defined as glycosylated haemoglobin A1c > 75 mmol/mol (~9%), which points to good metabolic control as an important preventive measure. Study II (cohort study, 167 diabetes patients) shows that most diabetic vitrectomy patients stand to gain visual acuity ≥0.3 after surgery. Visual acuity is stable after 1 year, and the stability is maintained through 10 years of follow-up. The use of silicone oil for endotamponade is a consistent long-term predictor of low vision after surgery. The risk of requiring cataract surgery after diabetic vitrectomy is substantial, and the risk increases if silicone oil is used. Study III (cohort study, 285 diabetes patients) shows, on the other hand, that diabetes patients can expect a significant improvement in visual acuity after cataract surgery, regardless of the degree of diabetic retinopathy. Poor preoperative visual acuity, a high degree of diabetic retinopathy and advanced age are predictors of a poor visual acuity after surgery. The risk of diabetic macular oedema after surgery is 4%. Finally, Study IV (case-control study, 2066 type 1 diabetes patients) demonstrates that diabetic papillopathy shares characteristics with diabetic retinopathy. The risk of experiencing diabetic papillopathy increases markedly with a drastic, recent reduction in glycosylated haemoglobin A1c and a small optic disc. This lends support to the theory that diabetic eye complications may occur in anatomically predisposed patients in response to metabolic control variability. Overall, results after intraocular surgery in diabetes patients are favourable. Surgery, however, is associated with costs to society, patient discomfort and risk of complications. This thesis provides an analysis of risk factors for intraocular surgery and identifies prognostic factors for visual acuity after surgery, which can be used for preventive purposes, surgical decision-making and patient counselling.

Epidemiological issues in diabetic retinopathy

There is currently an epidemic of diabetes in the world, principally type 2 diabetes that is linked to changing lifestyle, obesity, and increasing age of the population. Latest estimates from the International Diabetes Federation (IDF) forecasts a rise from 366 million people worldwide to 552 million by 2030. Type 1 diabetes is more common in the Northern hemisphere with the highest rates in Finland and there is evidence of a rise in some central European countries, particularly in the younger children under 5 years of age. Modifiable risk factors for progression of diabetic retinopathy (DR) are blood glucose, blood pressure, serum lipids, and smoking. Nonmodifiable risk factors are duration, age, genetic predisposition, and ethnicity. Other risk factors are pregnancy, microaneurysm count in an eye, microaneurysm formation rate, and the presence of any DR in the second eye. DR, macular edema (ME), and proliferative DR (PDR) develop with increased duration of diabetes and the rates are dependent on the above risk factors. In one study of type 1 diabetes, the median individual risk for the development of early retinal changes was 9.1 years of diabetes duration. Another study reported the 25 year incidence of proliferative retinopathy among population-based cohort of type 1 patients with diabetes was 42.9%. In recent years, people with diabetes have lower rates of progression than historically to PDR and severe visual loss, which may reflect better control of glucose, blood pressure, and serum lipids, and earlier diagnosis.

Systemic factors influence the prognosis of diabetic macular edema after pars plana vitrectomy with internal limiting membrane peeling

PURPOSE/AIMS

To evaluate the prognostic factors for the best corrected visual acuity (BCVA) and central subfield macular thickness (CSMT) after vitrectomy with internal limiting membrane (ILM) peeling for diabetic macular edema.

MATERIALS AND METHODS

A total of 44 eyes of 35 patients who had undergone vitrectomy with ILM peeling between March 2008 and September 2009 were examined. The relationships between preoperative systemic or ocular factors and BCVA or CSMT were evaluated before and at 6 months after the surgical procedure.

RESULTS

Mean logarithm of the minimum angle of resolution improved from 0.74 ± 0.35 (mean ± SD) preoperatively to 0.55 ± 0.4 at 6 months postoperatively (p = 0.001). There was a significant improvement of the CSMT from 482 ± 116 μm before the operation to 355 ± 126 μm 6 months after the operation (p < 0.0001). The preoperative CSMT was significantly thicker with ischemic disease (p = 0.0016). Preoperative BCVA was significantly lower when subfoveal hard exudate was present (p = 0.0005). At the 6-month follow-up, CSMT was significantly thicker when there was a higher glycosylated hemoglobin (p = 0.008). BCVA at the 6-month follow-up was significantly lower in the group without any diabetes treatment history (p = 0.0075) prior to the diagnosis of diabetic retinopathy.

CONCLUSIONS

While BCVA and CSMT were associated with ocular factors before surgery, they were associated with glycemic control postoperatively. Glycemic control may be important for retinal thickness after ocular surgery.

Blood pressure, vessel caliber, and retinal thickness in diabetes

PURPOSE

In this study, we examine the association of blood pressure (BP), retinal thickness (RT), and vessel caliber in patients with type 2 diabetes and high HbA1c (elevated long-term blood glucose) with or without mild or moderate nonproliferative diabetic retinopathy (NPDR).

METHODS

Forty-three patients with type 2 diabetes and high HbA1c measures (23 without NPDR and 20 with mild to moderate NPDR) and 22 age-matched nondiabetic controls participated. The BP, RT (Stratus OCT3), fundus photography, and HbA1c were measured. Correlations between BP, HbA1c, vessel caliber, and RT were evaluated.

RESULTS

Diastolic BP (DBP) is positively and significantly associated with RT in patients with NPDR (p < 0.02). Blood pressure was not associated with RT in patients without NPDR (p = 0.83). There is an association between higher HbA1c and higher DBP within the NPDR group (p < 0.02). Furthermore, HbA1c modifies the slope of the relationship between DBP and RT in NPDR patients. Greater venule diameters and loss of the correlation between decreased arteriole size and increased systolic blood pressure, seen in controls, were observed in patients with and without NPDR.

CONCLUSIONS

The results of this study show that HbA1c and BP together have an impact on RT measures of patients with DR. These measures should be considered when evaluating RT in patients with DR both clinically and in future optical coherence tomography studies on this population.

Identification of independent risk factors for the development of diabetic retinopathy requiring treatment

INTRODUCTION

Diabetic retinopathy is screened by fundus photography and screening intervals are defined according to general rules to ensure that vision threatening complications are detected even if the progression of the disease is fast. The resulting superfluous examinations of patients with slow disease progression can be reduced by a more exact decision model that allows an adjustment of the screening interval to each patient's individual risk profile. This requires an identification of independent risk factors for reaching treatment end points for diabetic retinopathy.

METHODS

Clinical data from 5365 patients who had undergone 23 324 examinations at the Department of Ophthalmology, Århus University Hospital between Jan 1st 1994 and Dec 31st 2007 were used to identify independent risk factors for progression of treatment requiring retinopathy.

RESULTS

The risk of reaching a treatment end point was in both diabetes types independently affected by retinopathy grade and HbA1c. Furthermore, in type 1 diabetic patients the risk of reaching a treatment end point was independently affected by disease duration and by a recommended control interval of less than 3 months, in spite of correction for retinopathy grade and other studied confounders, whereas in type 2 diabetes this risk was affected by increasing age of diagnosis of the disease.

CONCLUSIONS

Only a subset of known risk factors for development and progression of diabetic retinopathy should be used to construct a decision model for optimizing screening intervals for diabetic retinopathy.

Medical and psychological risk factors for incident hypertension in type 1 diabetic african-americans

Objective. To determine risk factors for the development of hypertension among African-Americans living with type 1 diabetes. Methods. African-Americans with type 1 diabetes (n = 483) participated in a 6-year followup. At both baseline and followup blood pressure was measured twice in both sitting and standing positions using a standard protocol. Patients had a structured clinical interview, ocular examination, retinal photographs, and blood and urine assays and completed the Hostility and Direction of Hostility Questionnaire (HDHQ) and the Beck Depression Inventory (BDI). Results. Of the 280 diabetic patients with no hypertension at baseline, 82 (29.3%) subsequently developed hypertension over the 6-year followup. Baseline older age, longer duration of diabetes, family history of hypertension, greater mean arterial blood pressure, overt proteinuria, increasing retinopathy severity, peripheral neuropathy, smoking, and higher hostility scores were significantly associated with the development of hypertension. Multivariate analyses showed that higher hostility scores and overt proteinuria were significantly and independently associated with the development of hypertension in this population. Conclusions. The development of hypertension in African-Americans living with type 1 diabetes appears to be multifactorial and includes both medical (overt proteinuria) as well as psychological (high hostility) risk factors.

Prediction, by retinal location, of the onset of diabetic edema in patients with nonproliferative diabetic retinopathy

PURPOSE

To formulate a model to predict the location of the onset of diabetic retinal edema (DE) in adults with diabetic retinopathy (DR), at risk for DE.

METHODS

In all, 46 eyes from 23 patients with DR were included. Subjects were followed semiannually until DE developed or the study concluded. The presence or absence of DE within the central 45 ° at the final visit was the outcome measure, and data from the prior visit were used as baseline. A logistic regression model was formulated to assess the relationship between DE development and: multifocal electroretinogram (mfERG) implicit time (IT) Z-score, mfERG amplitude (Amp) Z-score, sex, diabetes duration, diabetes type, blood glucose, HbA1c, age, systolic (SBP) and diastolic blood pressure, and grade of retinopathy. A total of 35 retinal zones were constructed from the mfERG elements and each was graded for DE. Data from 52 control subjects were used to calculate the maximum IT and minimum Amp Z-scores for each zone. Receiver operating characteristic curves from a fivefold cross-validation were used to determine the model's predictive properties.

RESULTS

Edema developed in 5.2% of all retinal zones and in 35% of the eyes. The mfERG Amp, mfERG IT, SBP, and sex were together predictive of edema onset. Combined, these factors produce a model that has 84% sensitivity and 76% specificity.

CONCLUSIONS

Together mfERG, SBP, and sex are good predictors of local edema in patients with DR. The model is a useful tool for assessing risk for edema development and a candidate measure to evaluate novel therapeutics directed at DE.

[Clinical and pharmacological factors related to the requirements of laser photocoagulation in patients with diabetic nephropathy due to type 2 diabetes mellitus]

BACKGROUND AND OBJECTIVE

Diabetic retinopathy is a microvascular complication of diabetes mellitus whose prevalence is closely related to the presence of nephropathy and hypertension. The aim was to study clinical and pharmacological factors that are associated with an increased need for laser photocoagulation in patients with diabetic nephropathy and retinopathy.

PATIENTS AND METHODS

Cross sectional study of 63 patients followed in the Diabetic Nephropathy consultation. Patients were divided into 2 groups according to whether or not previously have received photocoagulation. In each subgroup were studied demographic variables, anthropometric, laboratory, cardiovascular risk factors and treatment received by each patient for the control of hypertension, diabetes and others diseases.

RESULTS

We observed that the group had received photocoagulation had more years of diabetes evolution, more history of cardiovascular disease and a lower creatinine clearance. Similarly, the percentage of patients treated with carvedilol was significantly higher in the subgroup who had not received photocoagulation while the percentage of patients treated with beta-blockers was significantly higher in the subgroup that received photocoagulation; no significant differences was observed in the degree of control blood pressure.

CONCLUSIONS

Clinical and pharmacological factors related to the requirements of laser photocoagulation were years of diabetes evolution, history of cardiovascular disease, the stage of kidney disease and the treatment with beta-blockers.

Mitigating micro-and macro-vascular complications of diabetes beginning in adolescence

Diabetes is a chronic disorder, which manifests when insulin levels or resistance to insulin action becomes insufficient to control systemic glucose levels. Although the number of available agents to manage diabetes continues to expand rapidly, the maintenance of euglycemia by individuals with diabetes remains a substantial challenge. Unfortunately, many patients with type 1 and type 2 diabetes will ultimately experience diabetes complications. These complications result from the toxic effects of chronic hyperglycemia combined with other metabolic derangements that afflict persons with diabetes. This review will present a comprehensive look at the complications of diabetes, the risk factors for their progression, the mechanistic basis for their development, and the clinical approach to screening for, preventing, and treating these sequelae. In addition, since diabetes is commonly diagnosed in childhood, we will provide a special focus on the care of the adolescent patient.

Risk Factors for Diabetic Retinopathy among Jordanian Diabetics

PURPOSE

To identify the risk factors associated with diabetic retinopathy among diabetic patients at Jordan University Hospital.

METHODS

A total of 986 patients with diabetes mellitus were assessed at Jordan University Hospital. The assessment included detailed relevant history, complete medical and ophthalmic evaluation.

RESULTS

Out of the 1961 eye examined, 64.1 percent had one form of diabetic retinopathy; 54.8 percent had nonproliferative diabetic retinopathy (NPDR), 9.3 percent had proliferative diabetic retinopathy (PDR) and 30.8 percent had maculopathy. Of all participants, 23.5 percent had combined NPDR and maculopathy while 7.6 percent had PDR and maculopathy. Using logistic regression analysis it was shown that old age group, long duration of diabetes, poor glycemic control, uncontrolled blood pressure and the presence of nephropathy were significantly associated with diabetic retinopathy. The incidence of maculopathy was significantly associated with the presence of hypertension, protienuria and high cholesterol level.

CONCLUSION

The challenge for the primary care physician and diabetologist is to attain excellent glycemic control, aggressive control of blood pressure and normalization of blood lipid in order to reduce the risk of blindness and lessen the burden from diabetic retinopathy.

Article Commentary: The English national screening programme for sight-threatening diabetic retinopathy

Objectives

The main objective of the national screening programme is to reduce the risk of sight loss among people with diabetes due to diabetic retinopathy (DR).

Methods

Offering two-field mydriatic digital photographic screening to all people with diabetes in England over the age of 12 years.

Stage of development

The programme is in its infancy, receiving the first year's annual reports from approximately 96 screening programmes, each of which have developed to offer screening to a minimum number of 12,000 people with diabetes, which would cover a population of 350,000 people with 3.4% diabetes prevalence. The national programme has commenced the External quality assurance (QA) programme in order to achieve and sustain the highest possible standards.

Potential benefits

England has a population of two million people with diabetes over the age of 12 and it is believed that there is a prevalence of blindness of 4200 and an annual incidence of blindness of 1280 people with diabetes. This programme has the potential to reduce the prevalence of blindness in England from 4200 people to 1000 people and a conservative estimate of reducing the annual incidence of DR blindness by one-third would save 427 people per annum from blindness. These figures are based on the UK certification of blindness but if World Health Organization (WHO) definitions are used the prevalence, incidence and potential reductions in blindness are much greater.

Early changes in glomerular size selectivity in young adults with type 1 diabetes and retinopathy. Results from the Diabetes Incidence Study in Sweden

OBJECTIVE

To investigate the relationship between early-onset retinopathy and urinary markers of renal dysfunction.

RESEARCH DESIGN AND METHODS

The Diabetes Incidence Study in Sweden (DISS) aims to register all new cases of diabetes in young adults (15-34 years). In 1987-1988, 806 patients were reported and later invited to participate in a follow-up study focusing on microvascular complications after approximately 10 years of diabetes. In the present study, 149 patients with type 1 diabetes, completed eye examination, and urine sampling were included.

RESULTS

The patients with retinopathy (n=58, 39%) had higher HbA(1c) (P<.001) and urinary IgG2/creatinine (P<.05) and IgG2/IgG4 ratios (P<.05). Patients with maculopathy had the highest levels. No significant differences in urinary albumin/creatinine, glycosaminoglycans (GAGs)/creatinine, Tamm-Horsfall protein (THP)/creatinine, and IgG4/creatinine ratios were found. Women had higher urinary albumin/creatinine (P<.01) and urinary IgG2/creatinine ratios (P<.01) than men.

CONCLUSIONS

Young adults with type 1 diabetes and early-onset retinopathy had higher IgG2/creatinine and IgG2/IgG4 ratios than patients without retinopathy indicating that retinopathy is associated with a change in glomerular size selectivity. This was found in association with normal urinary albumin and THP excretion and may be suspected to reflect early general vascular changes.

Circulating antipericyte autoantibodies: a novel modifier of risk of progression of diabetic retinopathy?

BACKGROUND

Antipericyte autoantibodies (APAAs) are present in high frequency among diabetic subjects with and without nonproliferative retinopathy. This study aimed to determine whether progression of retinopathy in type 2 diabetes was associated with the same medical risk factors in APAA-positive subjects as in APAA-negative subjects.

METHODS

Type 2 diabetic patients with nonproliferative diabetic retinopathy at baseline were followed prospectively for 2 years monitoring progression of retinopathy. Thirty-eight (21.7%) of 175 patients had progression in Early Treatment Diabetic Retinopathy Study grade by > or =2 steps in at least 1 eye. Serum APAAs were detected by immunofluorescence on tissue-cultured bovine retinal pericytes.

RESULTS

Progression of retinopathy was associated with HbA(1c) level (P = 0.002), diabetes duration (P = 0.03), and albumin/creatinine ratio (P = 0.02) in APAA-negative subjects but not in APAA-positive subjects. The association between progression and APAAs was strongest in the upper quartile for HbA(1c) level (>8.0%), where 71.4% of patients negative for APAAs had progression of retinopathy while only 24.1% of patients positive for APAAs had progression (P = 0.007).

CONCLUSION

The results suggest that APAA presence is a modifier of risk of progression of retinopathy due to hyperglycemia and that it could be useful as a biochemical marker of risk of progression of diabetic retinopathy in type 2 diabetic patients with poor metabolic control.

Ambulatory blood pressure monitoring and progression of retinopathy in normotensive, normoalbuminuric type 1 diabetic patients: a 6-year follow-up study

To investigate the relationship between diabetic retinopathy (DR) and 24-h ambulatory blood pressure (ABP) in a cohort of normotensive, normoalbuminuric type 1 diabetic patients. This is a 6.1+/-3.3 year prospective study of 44 normotensive, normoalbuminuric type 1 diabetic patients. ABP was measured at the beginning and at the end of the study. Measurements of urinary albumin excretion rate (UAER) and direct and indirect ophthalmoscopy after mydriasis were performed at the start and end of the study and at least once a year. DR was observed in 12 patients at baseline. At the end of the study, eight of these patients had progressed to more advanced stages of retinopathy. Four patients developed retinopathy after the study began. These patients were grouped and classified as progressors. At baseline, progressors were older, had longer duration of diabetes, higher levels of UAER, and higher 24-h diastolic (P=0.03) and diurnal diastolic blood pressure (P=0.03). UAER and diastolic blood pressure (24h or day) remained significantly associated with development and progression of DR after multivariate analysis. High normal ABP was associated with the development or progression of DR in this cohort of normotensive, normoalbuminuric type 1 diabetic patients. Abnormalities in blood pressure homeostasis could indicate higher susceptibility to DR.

Albuminuria and hypertension are independently associated with circulating antipericyte autoantibodies in type 2 diabetic patients

AIMS

To determine whether albuminuria, hypertension, or HbA 1c are independently associated with antipericyte autoantibodies (APAAs) in type 2 diabetes mellitus.

METHODS

Two hundred ninety-nine subjects with different degrees of retinopathy according to the Early Treatment Diabetic Retinopathy Study Scale participated in this study. Albuminuria was defined as an albumin/creatinine ratio above the normal cutoff limit, that is, 2.0 g/mol for men and 2.8 g/mol for women. Hypertension was defined as a diastolic blood pressure more than 90 mm Hg, a systolic blood pressure more than 140 mm Hg, or pharmacological antihypertensive treatment. Serum APAAs were detected by immunofluorescence on tissue-cultured bovine retinal pericytes. Association analysis was performed using univariate and multivariate statistical tools.

RESULTS

In type 2 diabetes, APAAs were independently associated with albuminuria (OR = 0.56; P < .04), hypertension (OR = 2.21; P < .01), as well as with proliferative retinopathy (OR = 0.39; P < .01).

CONCLUSIONS

The increased prevalence of APAA in patients with hypertension may suggest that these antibodies are related to tissue damage and repair and that the decline in frequency with albuminuria may serve as a marker for more advanced angiopathy. Future longitudinal studies are needed to determine whether the frequency of APAA is associated with the progression of angiopathy, and to determine the biological activity and antigens recognized by the antibody.

Pathogenesis of diabetic retinopathy and the renin-angiotensin system

Despite the beneficial effects of good glycaemic control, loss of vision because of diabetic retinopathy (DR) still occurs. Recent studies have suggested that hypertension is a risk factor for the development and progression of DR and that blood pressure reduction can delay the progression of retinopathy. The renin-angiotensin system is activated by chronic hyperglycaemia, and the vitreous fluid level of angiotensin II (AII) is elevated in patients with proliferative diabetic retinopathy and diabetic macular oedema. AII increases vascular permeability and promotes neovascularization. It has been suggested that an autocrine-paracrine relationship may exist between AII and vascular endothelial growth factor in the ocular tissues. Accordingly, angiotensin-converting enzyme inhibitors or AII Type 1 (AT1) receptor blockers may be useful therapeutic agents for preventing the progression of DR.

Increased serum IGF-I during pregnancy is associated with progression of diabetic retinopathy

The IGF system has been associated with development and progression of diabetic retinopathy. We examined whether a simple measurement of the IGF system (serum total IGF-I) correlated with progression of diabetic retinopathy in pregnancy in type 1 diabetes. A prospective observational study was performed in 103 pregnant women with type 1 diabetes. Serum IGF-I was measured in maternal serum from week 14, every fourth week until week 30, and every second week until delivery. Twenty-four-hour blood pressure was measured with a portable oscillometry monitor. The women had visual acuity testing and fundus photography before pregnancy, once in each trimester, and 4 months after birth. Each eye was assigned an overall retinopathy grade on a scale from 1 to 6 independently by two experienced graders. During pregnancy, serum IGF-I increased with increasing gestational age until a plateau was reached in week 32. Progression of retinopathy was significantly associated with a higher level of IGF-I (P < 0.01). Serum IGF-I increased with increasing progression of retinopathy. Change of retinopathy was significantly associated with level of IGF-I (P < 0.01). During pregnancy, serum IGF-I increased with increasing birth weight until a plateau was reached in week 32. Birth weight was significantly associated with a higher level of serum IGF-I (P < 0.01).

Blood pressure and cardiac autonomic function in relation to risk factors and treatment perspectives in Type 1 diabetes

The cumulative incidence of diabetic nephropathy in Type 1 diabetes mellitus is in the order of 25 30%. The recognition that elevated blood pressure (BP) is a major factor in the progression of these patients to end-stage renal failure has led to the widespread use of antihypertensive therapy in order to preserve glomerular filtration rate and ultimately to reduce mortality. The routine measurement of microalbuminuria allows early identification of the subgroup of patients at increased risk of developing clinical nephropathy. Microalbuminuric Type 1 diabetic patients show a number of characteristic pathological abnormalities. In addition to elevated BP and abnormal circadian rhythm, there are also associated abnormalities of vagal function, lipid profile and endothelial function, as well as an increased prevalence of retinopathy. The first section of this two-part review focusses on the early changes associated with renal involvement in Type 1 diabetes. It addresses the associations between urinary albumin excretion, glycaemic control, smoking, BP, circadian BP variation, QT interval abnormalities and autonomic function in three groups of patients; those with normoalbuminuria, those progressing towards microalbuminuria and those with established low-grade microalbuminuria.

Haemodynamics in microvascular complications in type 1 diabetes

Type 1 diabetes is commonly associated with microvascular complications. Most of the microvascular blood vessels are involved but those in the kidney, retina and large nerves exhibit the more significant pathology. Haemodynamic and metabolic factors both alone and through the activation of a common pathway contribute to the characteristic dysfunction observed in diabetic vasculopathy. The haemodynamic abnormalities in type 1 diabetes are characterized by increased systemic blood pressure and altered blood flow with subsequent activation of various vasoactive factors, which can contribute to the maintenance of the haemodynamic alterations and to the development and progression of the microvascular complications. These vasoactive factors include vasoconstrictors such as angiotensin II, and endothelin, as well as vasodilators such as nitric oxide (NO). Systemic hypertension and vasoactive factors independently and in interaction with the metabolic pathway activate intracellular second messengers, nuclear transcription factors and various growth factors which lead to the typical functional and structural alterations of diabetic microvascular complications. Therapeutic strategies involved in the management and prevention of diabetic complications currently include antihypertensive agents, particularly those that interrupt the renin-angiotensin system. Further understanding of the interactions among the vasoactive factors, the intracellular second messengers and the growth factors may help to identify novel strategies to influence the action of the vasoactive factors. These novel therapies, together with specific inhibitors of the metabolic pathway or the common pathway, may provide the possibility of preventing or even reversing the progression of diabetic microvascular complications.

Diabetic retinopathy, visual acuity, and medical risk indicators: a continuous 10-year follow-up study in Type 1 diabetic patients under routine care

The objective of this study was to describe incidence and progression of diabetic retinopathy in relation to medical risk indicators as well as visual acuity outcome after a continuous follow-up period of 10 years in a Type 1 diabetic population treated under routine care. The incidence and progression of retinopathy and their association to HbA(1c), blood pressure, urinary albumin, serum creatinine levels, and insulin dosage were studied prospectively in 452 Type 1 diabetic patients. The degree of retinopathy was classified as no retinopathy, background, or sight-threatening retinopathy, i.e. clinically significant macular edema, severe nonproliferative, or proliferative retinopathy. Impaired visual acuity was defined as a visual acuity <0.5 and blindness as a visual acuity < or =0.1 in the best eye. In patients still alive at follow-up (n=344), 61% (69/114) developed any retinopathy, 45% (51/114) background retinopathy, and 16% (18/114) sight-threatening retinopathy. Progression from background to sight-threatening retinopathy occurred in 56% (73/131). In 2% (6/335), visual acuity dropped to <0.5 and in less than 1% (3/340) to < or =0.1. Patients who developed any retinopathy and patients who progressed to sight-threatening retinopathy had higher mean HbA(1c) levels over time compared to those who remained stable (P<.001 in both cases). Patients who developed any retinopathy had higher levels of mean diastolic blood pressure (P=.036), whereas no differences were seen in systolic blood pressure levels between the groups. Cox regression analysis, including all patients, showed mean HbA(1c) to be an independent risk indicator for both development and progression of retinopathy, whereas mean diastolic blood pressure was only a risk indicator for the incidence of retinopathy. Metabolic control is an important risk indicator for both development and progression of retinopathy, whereas diastolic blood pressure is important for the development of retinopathy in Type 1 diabetes. The number of patients who became blind during 10 years of follow-up was low.

Systemic considerations in the management of diabetic retinopathy

PURPOSE

To highlight the systemic factors which affect onset and/or progression of diabetic retinopathy (DR) and to emphasize the role and responsibilities of ophthalmologists and other eye care providers to ensure that appropriate systemic medical evaluation of the patient with diabetes is being pursued.

DESIGN

Literature review of publications relevant to diabetic retinopathy, blood glucose control, diabetes mellitus type, hypertension, renal disease, elevated serum lipids, exercise, pregnancy, anticoagulation, thrombolysis, smoking, anemia and antioxidant ingestion.

FINDINGS

Intensive blood glucose control and control of systemic hypertension reduce the risk of new onset DR and slow the progression of existing DR. Severe DR may be an indicator of renal disease while severe renal disease and its treatment can affect the progression of DR. Elevated serum lipids are associated with macular exudate and moderate visual loss. Certain types of excessive exercise in patients with advanced stages of retinopathy may aggravate vitreous hemorrhage. During pregnancy, DR should be monitored closely as transient progression of DR can occur. Therapeutic anticoagulation and thrombolysis are not contraindicated at any stage of DR. Anemia can result in progression of DR, smoking in general should be discouraged, and the role of antioxidant therapy requires further study.

CONCLUSIONS

Blindness from diabetic retinopathy is now largely preventable with timely detection and appropriate interventional therapy. Routine, repetitive, lifelong, expert clinical retinal examination is essential for the fundamental ophthalmic care of the patient with diabetes. However, diabetes mellitus is a systemic disease and thus optimal ophthalmic care must include diligent evaluation and treatment of concomitant systemic disorders that influence the development, progression and ultimate outcome of diabetic retinopathy. Optimization of these systemic considerations through an intensive, multi-disciplinary, healthcare team-based approach will maximize the ophthalmic and general health of these patients. Ophthalmologists and other eye care providers are critical members of this team with unique responsibilities to ensure that appropriate systemic medical evaluation is being pursued.

Complications of pediatric and adolescent type 1 diabetes mellitus

Type 1 diabetes mellitus is potentially associated with serious microvascular and macrovascular complications, although these are usually subclinical during the pediatric and adolescent years. There is no "grace" period for the beginnings of such complications. Duration of diabetes, glycemic control, age, and pubertal stage are critical factors contributing toward development of such problems. Other risk factors include family history (genetic predisposition), hyperlipidemia, hypertension, and smoking. The Diabetes Control and Complications Trial (DCCT) proved the importance of glycemic control and emphasized the ability of improved glucose control to prevent or decrease retinopathy, nephropathy, and neuropathy using a multidisciplinary same-philosophy-of-care approach plus targeted glucose and hemoglobin A(1c) values. Other natural history and intervention studies support the findings of the DCCT. Although our current tools are not perfect, they allow us to decrease microangiopathic complications very significantly if we educate our patients and their family members. Metabolic control counts.

Macular circulation in patients with diabetes mellitus with and without arterial hypertension

BACKGROUND

Previous fluorescein angiographic studies have shown alterations in the macular microcirculation in patients with diabetes mellitus and arterial hypertension. In both diseases capillary blood velocity was reduced and capillary density decreased. These changes were more pronounced in diabetic patients. We have examined the influence of arterial hypertension in combination with diabetes mellitus.

METHODS

62 patients with diabetes mellitus and arterial hypertension (group 1) were matched with patients with diabetes mellitus but without arterial hypertension (group 2, match criteria: ETDRS stage of retinopathy). In all subjects fluorescein angiograms were performed with a scanning laser ophthalmoscope. Macular capillary blood velocity (CBV), perifoveal intercapillary area (PIA), the coefficient of variation of both parameters, the area of the foveal avascular zone (FAZ), and the arteriovenous passage time (AVP) were assessed by digital image analysis.

RESULTS

Systolic and diastolic blood pressures were significantly increased in the patients with arterial hypertension (systolic p=0.0008; diastolic p=0.03). Neither dynamic measures (AVP: 1.64 (0.49) seconds (group 1), 1.72 (0.58) seconds (group 2); CBV: 1.98 (0.39) mm/s (group 1), 2.09 (0.43) mm/s (group 2)) nor morphological measures (PIA: 7985 (3137) microm(2) (group 1), 8338 (3376) microm(2) (group 2); FAZ: 0.319 (0.206) mm(2) (group 1), 0.363 (0.237) mm(2) (group 2)) were significantly different between the two groups of diabetic patients.

CONCLUSION

Arterial hypertension did not result in more severe macular capillary dropout than diabetes without hypertension. This might be explained by the fact that most of the patients were being treated with antihypertensive drugs.

Early diabetes-related complications in children and adolescents with type 1 diabetes. Implications for screening and intervention

Although children and adolescents with type 1 diabetes are faced with the threat of the acute complications of hypoglycemia and ketoacidosis on a day-to-day basis, in the long-term, the microvascular and macrovascular complications of the disease place them at greatest risk for serious morbidity and earlier than expected mortality. The families of children with diabetes should be provided with information about the complications of diabetes beginning at the time of diagnosis, and this information needs to be reinforced throughout the follow-up period. Appropriate surveillance for the earliest evidence of microvascular disease should begin at the onset of puberty and after 3 to 5 years of diabetes. Therapeutic interventions, particularly excellent metabolic control, may be exceedingly effective in preventing complication onset or significantly retarding the rate of progression.

Risk factors for diabetic retinopathy among Saudi diabetics

PURPOSE

To describe the incidence of, and risk factors associated with, diabetic retinopathy in diabetic persons assessed at a Saudi diabetes centre.

METHODS

Five hundred and two patients with diabetes mellitus assessed by our service were studied. There were 174 patients (34.7%) with insulin-dependent diabetes mellitus (IDDM) and 328 patients (65.3%) with non-insulin-dependent diabetes mellitus (NIDDM).

RESULTS

The incidence of retinopathy was 157/502 (31.3%). The incidence was 42.5% in patients with IDDM and 25.3% in those with NIDDM. By logistic regression analysis, it was shown that old age (>60 years), insulin use, long duration of diabetes (>10 years), poor diabetes control, and the presence of nephropathy were significantly associated with the incidence of retinopathy. On the basis of the magnitudes of the regression coefficients in the hazard function, long duration of diabetes was the most important independent risk factor for the development of retinopathy; the presence of nephropathy, age >60 years, poor diabetes control, and use of insulin were less important (regression coefficients: 1.9, 1.71, 1.331, 0.8508 and 0.6178, respectively). The incidence of macular oedema was significantly associated with the presence of hypertension and high cholesterol levels in patients with IDDM. Polycotomous regression analysis showed that the presence of nephropathy was the only factor significantly associated with the severity of retinopathy.

CONCLUSIONS

The significant associations with poor control and duration of diabetes provide further strong evidence for the benefits of optimal glycaemic control. Other potentially modifiable risk factors for retinopathy may be important, including elevated blood pressure and serum cholesterol.

Diabetes complication screening in 937 children and adolescents

Results are presented of diabetes complication screening in children and adolescents aged 6-20 years. Their diabetes duration was 0.02-18.4 yr and median HbA1c over the preceding 36 months was 8.4% [IQR 7.8-9.3]. Gradable retinal photographs were obtained in 937: 110 less than 11 years (< 11 yr Gp). Albumin excretion rate (AER) was obtained from 3 timed overnight urine collections in 691: 100 in < 11 yr Gp. Early retinopathy was found in 27% (9% in < 11 yr Gp). Microalbuminuria (AER > or = 20 micrograms/min) was found in 4%. Significant individual risk factors for both complications were higher blood pressure, cholesterol, HbA1c, pubertal staging, older age and longer diabetes duration. Using multiple logistic regression, significant risk factors for retinopathy were longer duration and older age and in addition higher HbA1c. Diabetes complication screening detected early subclinical disease in children and adolescents who may benefit from lowering blood pressure and improving metabolic control. Screening should commence after five years of duration in young children, and after two years of duration in adolescents.

Monitoring for retinopathy in children and adolescents with type 1 diabetes

In children with an average diabetes onset at 11 y of age, the first retinal changes can be expected after a median diabetes duration of 9 y, while the median time until clinically relevant background retinopathy is 14 y. Periodic examinations of the retinal status become necessary with the onset of puberty or after 5 y of diabetes duration. Only sensitive methods should be used for retinopathy screening; the minimum recommended standard is a stereoscopic slit-lamp biomicroscopic examination in mydriasis. The degree of glycaemic control, both before and after puberty, appears to be of outstanding importance for the development of retinopathy, but the contribution of other factors (arterial blood pressure, lipid abnormalities, sex steroids, smoking and genetic factors) may be of varying relevance in the individual patient. Thus, to improve the long-term prognosis for children with diabetes appropriate screening for retinopathy and associated risk factors is mandatory.

Diabetic retinopathy in Down's syndrome

AIM

To determine the prevalence of diabetic retinopathy in patients with Down's syndrome and diabetes mellitus.

METHODS

Nine patients with Down's syndrome and diabetes mellitus were assessed. Factors recorded included type and duration of diabetes, level of diabetic control, blood pressure, urinalysis, and results of ophthalmological examination.

RESULTS

The duration of diabetes ranged from 8 to 41 years (mean 17.6 years). All had satisfactory glycaemic control and blood pressure measurements on the low side of normal (mean 106.6/70 mm Hg). One patient had early background diabetic retinopathy. The remainder had no evidence of diabetic retinopathy.

CONCLUSION

The low prevalence of diabetic retinopathy in these Down's syndrome patients, despite the long duration, is an interesting finding. It suggests some inherent protective factor against the development of diabetic retinopathy in this patient subgroup.

The association between retinopathy, nephropathy, cardiovascular disease and long-term metabolic control in type 1 diabetes mellitus: a 5 year follow-up study of 442 adult patients in routine care

The aim of the present study was to examine mean HbA1c and blood pressure levels during a 5 year period in 442 type 1 adult diabetic patients in relation to the incidence and progression of retinopathy, nephropathy and to cardiovascular morbidity and mortality. The study showed, that in patients under routine care at a diabetic unit with four visits to the out-patient clinic per year, the intraindividual coefficient of variation for HbA1c values was 11 +/- 4% (mean +/- S.D.), and 7 +/- 3 and 8 +/- 2% for systolic and diastolic blood pressure, respectively. In 121 patients without retinopathy at entry, the 5 year incidence of any retinopathy was 47% (n = 57). Patients who developed retinopathy had higher mean HbA1c levels (P < 0.01), as well as mean systolic (P < 0.01) and diastolic (P < 0.05) blood pressure levels. In 123 patients with background retinopathy at entry, progression to severe retinopathy, i.e. clinically significant macular oedema, severe non-proliferative or proliferative retinopathy, occurred in 41% (n = 51). In those patients, the degree of metabolic control was worse (P < 0.001), the systolic (P < 0.05) and diastolic (P < 0.01) blood pressure levels were higher. The patients were stratified into four groups according to their urinary albumin concentration at entry: (1) normal albuminuria (< 12.5 mg/l), (2) borderline albuminuria (12.5-30 mg/l), (3) microalbuminuria (31-299 mg/l), i.c. incipient nephropathy and (4) clinical nephropathy (> or = 300 mg/l). An increase of urinary albumin concentration in patients who had normoalbuminuria or borderline albuminuria at entry was associated with mean HbA1c levels (r = 0.24, P < 0.01 and r = 0.27, P < 0.01, respectively). No such association was seen in patients with microalbuminuria or clinical nephropathy at entry. There was no association between the increase of urinary albumin level and mean systolic blood pressure levels in patients who had normoalbuminuria and microalbuminuria at entry. In contrast, there was an association between the increase of urinary albumin level in patients with borderline albuminuria (r = 0.36, P < 0.001), clinical nephropathy (r = 0.26, P < 0.05) and mean systolic blood pressure (P < 0.05). There was no association between the increase of urinary albumin levels and mean diastolic blood pressure in any of the albuminuria groups. As for the incidence of cardiovascular disease, renal insufficiency or death, the duration of diabetes (P < 0.01), urinary albumin concentration at entry (P < 0.001), mean systolic blood pressure (P < 0.05) and treatment with loop diuretics (P < 0.001) were but age, age at onset of diabetes, mean levels of HbA1c and diastolic blood pressure as well as treatment with beta- or Ca-blockers or ACE inhibitors were not related to these end-points. In conclusion, the present study showed that there was an association between the degree of metabolic control and both development and progression of retinopathy and progression of nephropathy of early stages in type 1 diabetic patients treated under routine conditions. Moreover, both the incidence and progression of retinopathy and progression of nephropathy at later stages were also associated with the long-term blood pressure levels. However, HbA1c levels were not associated with morbidity and mortality in cardiovascular disease or development of renal insufficiency.

Analysis of the blood-retinal barrier: its relation to clinical and metabolic factors and progression to retinopathy in juvenile diabetics. A 4-year follow-up study

BACKGROUND

The study was carried out to evaluate the correlation between blood-retinal barrier (BRB) permeability and the development of diabetic retinopathy (DR) and to assess the metabolic and clinical factors related to DR over a 4-year period by means of vitreous fluorophotometry (VF).

METHODS

Thirty-five type I diabetics with no retinopathy, age 7-21 years (mean 14.32 +/- 2.1 years) were enrolled in this longitudinal study. Two visits included standard ophthalmological examination, fluorescein angiography and VF were performed, on entry into the study and 4 years later. The following risk factors in DR were analyzed: age, duration of diabetes, blood pressure, cholesterol, triglycerides, fasting blood glucose levels, glycosylated hemoglobin (HbA1c), insulin dose/kg body weight (IDBW), fructosamine and albuminuria. To estimate the BRB permeability we adopted the vitreous penetration ratio transmittance (VPRt) value.

RESULTS

At 4-year follow-up the mean VPRt had significantly increased. During that time 13 patients developed DR and their final mean VPRt was significantly higher than that in non-DR patients. Additionally, the initial mean VPRt was higher but not significantly so, in patients that later developed DR than in non-DR subjects. A constant linear correlation was found between VPRt and duration of diabetes, HbA1c and microalbuminuria.

CONCLUSION

VF is a quantitative method that could measure and predict the breakdown of the BRB before angiographic retinopathy in type I diabetics. The major clinical and metabolic factors related to alterations in the BRB are duration of diabetes, HbA1c and microalbuminuria.

Development and progression of diabetic retinopathy: adolescents at risk

The aims of this study were to evaluate short-term changes in retinopathy in adolescents, and to examine the relationship of these changes to risk factors. Two-hundred and three adolescents, with a median age of 14.5 (range 10.4 to 20.6) yr and a median duration of diabetes of 6.6 (1.1 to 16.3) yr, were included in the study. Retinopathy was assessed on two occasions, using stereoscopic fundus photography; the median time between assessment was 1.3 (0.5 to 3.0) yr. At baseline, 41% of the adolescents had background retinopathy. When patients were stratified according to the median diabetes duration (DD) (6.6 yr) and glycaemic control over the 12 months prior to assessment (HbA1C) (8.4%), the percentage of retinopathy in each group was: lowDD/lowHbA1C 13%; lowDD/highHbA1C 40%; highDD/lowHbA1C 42%; and highDD/highHbA1C 72%. Using a 2-step criteria for stability or change in retinopathy, 11% of the 203 adolescents showed progression of retinopathy, 41% had stable retinopathy, 5% showed regression, and 43% had no retinopathy at either assessment. Change in retinopathy was related to age at baseline assessment (borderline significance, p = 0.06), diabetes duration (p < 0.001), glycaemic control (p < 0.001) and total cholesterol (p = 0.04), and was also related to DD/HbA1C group membership (chi 2, p < 0.001). This study highlights the combined adverse effect of long diabetes duration and poor glycaemic control on the development and progression of retinopathy during adolescence, and identifies a group that is likely to show progression over a relatively short period.

The progression of retinopathy over 2 years: the Pittsburgh Epidemiology of Diabetes Complications (EDC) Study

This study examined potential risk factors for the incidence and progression of retinopathy in a large representative cohort of childhood onset insulin-dependent diabetic patients. Participants in the Epidemiology of Diabetes Complications (EDC) Study underwent a full clinical examination at baseline and again at a 2-year follow-up. Retinopathy status was ascertained using stereo fundus photographs graded according to the modified Airlie House System. The study population is based on a large cohort of childhood-onset insulin-dependent diabetic patients, seen within 1 year of diagnosis at the Children's Hospital of Pittsburgh between January 1950 and May 1980. A total of 657 subjects participated at baseline (1986-1988), with 80% of eligible survivors taking part in the follow-up examination. This report concerns risk factors associated with the progression of diabetic retinopathy over a 2-year period, and the interaction of these factors with the presence of nephropathy. Analyses showed that baseline diastolic blood pressure was significantly associated with the incidence of any retinopathy, while glycosylated hemoglobin, baseline severity of retinopathy, serum triglycerides, and, to a lesser extent, higher levels of low-density lipoprotein (LDL) cholesterol and fibrinogen were associated with the progression of retinopathy. Progression to proliferative retinopathy was related to higher LDL cholesterol, fibrinogen, serum triglycerides, albumin excretion rate, and glycosylated hemoglobin (GHb). Risk factors varied with the presence of nephropathy. In the absence of nephropathy, GHb was a significant predictor of progression, whilst this was not the case in the presence of nephropathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence and risk factors for retinopathy in adolescents with type 1 diabetes

OBJECTIVES

To establish the prevalence of, and risk factors associated with, diabetic retinopathy in an Australian adolescent diabetes clinic population.

DESIGN

A prospective longitudinal study; baseline findings.

PATIENTS

Two hundred and fifty-five patients with Type 1 (insulin-dependent) diabetes mellitus assessed by our service were studied. Entry criteria were: age 11.0-19.9 years; diabetes duration of at least two years; and gradable fundus photographs of at least one eye.

MAIN OUTCOME MEASURES

The presence and severity of retinopathy, as assessed by the grading of stereoscopic fundus photographs. Possible risk factors assessed were age, sex, diabetes duration, pubertal stage, blood pressure, glycaemic control and total cholesterol level.

RESULTS

The prevalence of retinopathy was 42%; all of those affected had mild background retinopathy. Highly significant associations were found with glycaemic control and both total and prepubertal duration of diabetes. No associations were found with age, sex, pubertal stage, blood pressure or total cholesterol level.

CONCLUSIONS

The high prevalence of early diabetic retinopathy in this group of Australian adolescents is comparable to recent reports from other centres. The significant associations with glycaemic control and duration of diabetes provide further strong evidence for the benefit of optimal glycaemic control during adolescence. Our finding that the prepubertal years of diabetes contribute to the development of retinopathy suggests that glycaemic control before puberty should also be optimised. The planned follow-up of this cohort will establish the risk of progression to vision-threatening retinopathy and allow risk factors to be further evaluated.

Severity of background retinopathy in type 1 diabetes increases with the level of long-term glycated haemoglobin

The relationship between severity of background retinopathy, and prior long-term glycaemic control was studied. Ninety patients with background retinopathy and Type 1 diabetes mellitus, diabetes duration < or = 25 years, and HbA1c monitored > 5 years (on average 9.2 years with 32 HbA1c measurements) were included. All patients had microaenurysms/haemorrhages, 33 had hard exudates, 27 soft exudates, 8 IRMA (intraretinal microangiopathy), three venous beading, and no patient had macula oedema. Patients with mean HbA1c > 8% had higher relative risks for all kinds of background retinopathy, compared to patients with HbA1c < or = 7%. In multiple regression analysis, long-term glycated haemoglobin had significant impact on all types of background retinopathy. Women had lower scores for all types of background retinopathy. No sex differences in HbA1c, age, or duration were found. We conclude that poor long-term glycaemic control is a major risk factor for all types of background retinopathy.

Factors influencing the onset and progression of diabetic retinopathy in subjects with insulin-dependent diabetes mellitus

BACKGROUND

The etiology of diabetic retinopathy is poorly understood. In the current study, factor associated with the onset and the progression or regression of retinopathy are evaluated.

METHODS

Two hundred seventy-seven subjects with insulin-dependent (type I) diabetes mellitus (IDDM) were evaluated longitudinally for retinal changes over a mean of 2.7 years. The multistate Markov model was used to analyze the influences of the duration of diabetes, a family history of hypertension, age, sex, cigarette smoking, systolic blood pressure, diastolic blood pressure, cholesterol levels, and longitudinal glycohemoglobin (GHb) values on the development and the progression or regression of retinopathy.

RESULTS

Univariate analysis confirmed that four factors were significantly associated with the etiology and the progression or regression of diabetic retinopathy: age, duration of diabetes, mean longitudinal GHb levels (all at P < 0.01), and diastolic blood pressure (P < 0.04). However, age was no longer significant when controlled by duration of diabetes. Cigarette smoking was only associated significantly with background retinopathy (stages 2 and 3). Systolic blood pressure, sex, a family history of hypertension, and cholesterol levels were not significantly associated with retinopathy.

CONCLUSIONS

The onset of diabetic retinopathy is associated with the duration of diabetes, mean longitudinal GHb levels, smoking, and diastolic blood pressure. A longer duration of diabetes, higher GHb values, and higher diastolic blood pressure levels are associated with an increased risk of progression and a decreased chance of regression of diabetic retinopathy.

Clinical and metabolic factors associated with the blood retinal barrier permeability in insulin dependent diabetes mellitus without retinopathy

The authors assessed a study pointing out the relationship between the permeability of Blood Retinal Barrier (BRB), using vitreous fluorophotometry, and several risk clinical and laboratory data in Insulin Dependent Diabetes Mellitus (IDDM). Eighty eyes of 40 IDDM patients were evaluated. Their mean age was 14.8 +/- 3.2 years. Twenty healthy volunteers served as control group (mean age 15.3 +/- 3.2 years). Preexisting diabetic retinopathy was dismissed after funduscopy and fluorescein angiography. The studied risk factors were: age, duration of diabetes, HLA antigens, blood pressure, cholesterol and triglycerides levels, glycosylated hemoglobin, insulin dose/kg body weight and fructosamine. Vitreous and lens fluorophotometry was performed in both groups (VPRt). The mean VPRt in IDDM patients was 3.56 +/- 1.47 x 10(-6) min-1. In healthy subjects it was 2.53 +/- 0.55 x 10(-6) min-1, establishing a significant difference (p < 0.01). We found a statistically significant correlation between VPRt and duration of diabetes, insulin dose/kg body weight and HbAlc. No correlation was found between VPRt and the rest of parameters. We conclude that vitreous fluorophotometry is a valid method to measure BRB; and the three factors mentioned above are related to the BRB permeability.

Elevation of resting and exercise blood pressures in subjects with type I diabetes and relation to albuminuria

The etiology of diabetic nephropathy is currently unknown, but blood pressure is believed an important risk factor. A total of 173 subjects with type I diabetes who participated in two or more exercise tests with simultaneous measurements of blood pressure (BP) and heart rate were studied. Subjects with diabetes had significantly elevated resting and exercise diastolic and systolic BPs when compared with controls. This was not related to the presence of albuminuria. During exercise, elevation of diastolic BP was present in 65 (38%) of the 173 test subjects. Elevated exercise diastolic BPs among the subjects with diabetes (excluding controls) was present only for subjects with elevated exercise and overnight albuminuria. It is concluded that factors other than early diabetic nephropathy are likely related to elevated resting and exercise BPs in subjects with diabetes compared with controls. Early renal damage, however, is related to further elevations in resting and exercise diastolic BPs within the group of subjects with diabetes.

Irreversible progression of severe retinopathy in young type I insulin-dependent diabetes mellitus patients after improved metabolic control

The impact of metabolic control on the development of rapidly progressive severe retinopathy was studied in 14 young type I insulin-dependent diabetes mellitus (IDDM) patients. Glycosylated hemoglobin (HbAlc) levels 45 months prior to and 12 months after the diagnosis of retinopathy were compared with HbAlc levels in 17 type I IDDM patients with no or minimal background retinopathy, matched for age and duration of diabetes. HbAlc levels were generally higher in patients with severe retinopathy (p less than 0.05) from 39 months until 6 months before the diagnosis of retinopathy. Thereafter, there was a gradual decrease in HbAlc levels reaching the same level as in control patients 6 months after diagnosis of retinopathy. Patients with severe retinopathy required higher doses of insulin prior to the diagnosis of retinopathy (p less than 0.05), but the insulin requirement decreased, and 12 months afterward, the insulin dosage was similar to patients with background retinopathy. Systolic blood pressure levels were slightly increased and higher in patients with severe retinopathy compared with control patients from 18 months before to diagnosis of retinopathy (p less than 0.05). Diastolic blood pressure levels likewise differed at 18 and 12 months before and at the time of diagnosis of retinopathy as well as 12 months afterward (p less than 0.05); however, no differences were seen in urinary albumin or serum creatinine levels between the groups. Thus, years of poor metabolic control, drastically improved, preceded the development of irreversible severe retinopathy in these young type I IDDM patients.

Limited joint mobility in subjects with insulin dependent diabetes mellitus: relationship with eye and kidney complications

Three hundred and fifty seven subjects (178 males and 179 females) with insulin dependent diabetes mellitus were evaluated for the presence of limited joint mobility of the interphalangeal joints. Sixty six subjects (19%) had stage 1 and 26 subjects (7%) had stage 2 involvement of their interphalangeal joints. The presence of contractures was significantly related to mean longitudinal glycated haemoglobin (HbA1) concentrations, duration of diabetes, age of onset, mean longitudinal cholesterol concentrations and blood pressure. Limited joint mobility was also significantly associated with early diabetic retinopathy and raised albumin excretion rates. Limited joint mobility remained a significant factor in the logistic regression model for albuminuria and grade of retinopathy when controlled for smoking, cholesterol concentrations, duration of diabetes, age, gender, and blood pressure. However, limited joint mobility was only significantly associated with diabetic retinopathy when the effect of HbA1 concentrations was included in the multivariate model.