Early worsening of diabetic retinopathy in the Diabetes Control and Complications Trial

Targeting intensive versus conventional glycaemic control for type 1 diabetes mellitus: a systematic review with meta-analyses and trial sequential analyses of randomised clinical trials

OBJECTIVE

To assess the benefits and harms of targeting intensive versus conventional glycaemic control in patients with type 1 diabetes mellitus.

DESIGN

A systematic review with meta-analyses and trial sequential analyses of randomised clinical trials.

DATA SOURCES

The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded and LILACS to January 2013.

STUDY SELECTION

Randomised clinical trials that prespecified different targets of glycaemic control in participants at any age with type 1 diabetes mellitus were included.

DATA EXTRACTION

Two authors independently assessed studies for inclusion and extracted data.

RESULTS

18 randomised clinical trials included 2254 participants with type 1 diabetes mellitus. All trials had high risk of bias. There was no statistically significant effect of targeting intensive glycaemic control on all-cause mortality (risk ratio 1.16, 95% CI 0.65 to 2.08) or cardiovascular mortality (0.49, 0.19 to 1.24). Targeting intensive glycaemic control reduced the relative risks for the composite macrovascular outcome (0.63, 0.41 to 0.96; p=0.03), and nephropathy (0.37, 0.27 to 0.50; p<0.00001. The effect estimates of retinopathy, ketoacidosis and retinal photocoagulation were not consistently statistically significant between random and fixed effects models. The risk of severe hypoglycaemia was significantly increased with intensive glycaemic targets (1.40, 1.01 to 1.94). Trial sequential analyses showed that the amount of data needed to demonstrate a relative risk reduction of 10% were, in general, inadequate.

CONCLUSIONS

There was no significant effect towards improved all-cause mortality when targeting intensive glycaemic control compared with conventional glycaemic control. However, there may be beneficial effects of targeting intensive glycaemic control on the composite macrovascular outcome and on nephropathy, and detrimental effects on severe hypoglycaemia. Notably, the data for retinopathy and ketoacidosis were inconsistent. There was a severe lack of reporting on patient relevant outcomes, and all trials had poor bias control.

28-week, randomized, multicenter, open-label, parallel-group phase III trial to investigate the efficacy and safety of biphasic insulin aspart 70 thrice-daily injections vs twice-daily injections of biphasic insulin aspart 30 in patients with type 2 diabetes

Aims/Introduction:  An insulin analogue formulation with a 7:3 ratio of rapid‐acting and intermediate‐acting fractions, biphasic insulin aspart 70 (BIAsp70) was developed to supplement basal insulin between meals and mimic the physiological pattern of postprandial insulin secretion.

Materials and Methods:  We carried out a randomized, open‐label study to compare the efficacy and safety profiles of BIAsp70 and an insulin analogue formulation with a 3:7 ratio of rapid‐acting and intermediate‐acting fractions (BIAsp30) in type 2 diabetes mellitus patients. Patients were randomized and received either thrice‐daily BIAsp70 (n = 145) or twice‐daily BIAsp30 (n = 144) for 28 weeks. The primary end‐point was glycated hemoglobin (HbA_1c) after 16 weeks of treatment.

Results:  Non‐inferiority of BIAsp70 vs BIAsp30 was confirmed and superiority was established with a between‐group difference (BIAsp70–BIAsp30) in HbA_1c after 16 weeks of treatment of −0.35% (95% CI: −0.51 to −0.19; P < 0.0001 for superiority). The mean postprandial glucose increment (19.96 vs 54.35 mg/dL; P < 0.0001) and M‐value (12.99 vs 17.94; P < 0.0001) at 16 weeks were smaller in the BIAsp70 group than in the BIAsp30 group, and were maintained at 28 weeks. Pre‐breakfast glucose (157.9 vs 140.7 mg/dL), total insulin dose (46.8 vs 38.1 U/day) and weight gain (+1.94 vs 1.23 kg) at week 28 were greater in the BIAsp70 group. Incidence of nocturnal hypoglycemia was significantly lower with BIAsp70 vs BIAsp30 (1.23 vs 3.21 events/subject year; P = 0.0002) at week 28.

Conclusions:  Thrice‐daily BIAsp70 was superior to twice‐daily BIAsp30 in terms of HbA_1c change, with less variation in daytime plasma glucose profiles. BIAsp70 was well tolerated, with a lower incidence of nocturnal hypoglycemia vs BIAsp30. This trial was registered with ClinicalTrial.gov (no. NCT00318786). (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00015.x, 2010)

Efficacy and safety of patient-directed titration of once-daily pre-dinner premixed biphasic insulin aspart 70/30 injection in Japanese type 2 diabetic patients with oral antidiabetic drug failure: STEP-AKITA study

Aims/Introduction:  To clarify clinical characteristics related to optimal glycemic control achieved after adding once‐daily pre‐dinner biphasic insulin aspart 70/30 (BIAsp 30) in Japanese type 2 diabetic (T2D) patients with oral antidiabetic drug (OAD) failure.

Materials and Methods:  Under this regimen, we evaluated changes in HbA_1c levels and daily self‐monitoring blood glucose (BG) profiles, as well as the incidences of hypoglycemia and retinopathy progression. The patients adjusted BIAsp 30 dosages themselves every 3–4 days according to a pre‐determined algorithm to achieve fasting BG levels of 101–120 mg/dL. HbA_1c levels were expressed as Japan Diabetes Society values.

Results:  Of 29 enrolled patients, 22 (HbA_1c levels, 8.5 ± 1.5% [mean ± SD]) and 20 patients completed the 16‐ and 24‐week follow‐up, respectively. At 16 weeks 68.2 and 45.5%, and at 24 weeks 80.0 and 35% of patients had achieved HbA_1c levels of <7.0 and <6.5%, respectively. The patients who had achieved optimal glycemic control, including daytime postprandial BG profiles after treatment, had lower post‐breakfast BG excursions at baseline, shorter diabetes durations and younger age. No severe hypoglycemic episodes were recorded. Progression of retinopathy was observed in 3 of the 29 enrolled patients.

Conclusions:  Lower post‐breakfast BG excursions, shorter diabetes duration and younger age in Japanese T2D patients with OAD failure might warrant optimal glycemic control with safety after adding once‐daily pre‐dinner BIAsp 30 initiating regimen. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00062.x, 2010)

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.

Posttranslational modification of mitochondrial transcription factor A in impaired mitochondria biogenesis: implications in diabetic retinopathy and metabolic memory phenomenon

Mitochondrial transcription factor A (TFAM) is one of the key regulators of the transcription of mtDNA. In diabetes, despite increase in gene transcripts of TFAM, its protein levels in the mitochondria are decreased and mitochondria copy numbers become subnormal. The aim of this study is to investigate the mechanism(s) responsible for decreased mitochondrial TFAM in diabetes. Using retinal endothelial cells, we have investigated the effect of overexpression of cytosolic chaperone, Hsp70, and TFAM on glucose-induced decrease in mitochondrial TFAM levels, and the transcription of mtDNA-encoded genes, NADH dehydrogenase subunit 6 (ND6) and cytochrome b (Cytb). To investigate the role of posttranslational modifications in subnormal mitochondrial TFAM, ubiquitination of TFAM was assessed, and the results were confirmed in the retina from streptozotocin-induced diabetic rats. While overexpression of Hsp70 failed to prevent glucose-induced decrease in mitochondrial TFAM and transcripts of ND6 and Cytb, overexpression of TFAM ameliorated decrease in its mitochondrial protein levels and transcriptional activity. TFAM was ubiquitinated by high glucose, and PYR-41, an inhibitor of ubiquitination, prevented TFAM ubiquitination and restored the transcriptional activity. Similarly, TFAM was ubiquitinated in the retina from diabetic rats, and it continued to be modified after reinstitution of normal glycemia. Our results clearly imply that the ubiquitination of TFAM impedes its transport to the mitochondria resulting in subnormal mtDNA transcription and mitochondria dysfunction, and inhibition of ubiquitination restores mitochondrial homeostasis. Reversal of hyperglycemia does not provide any benefit to TFAM ubiquitination. Thus, strategies targeting posttranslational modification could provide an avenue to preserve mitochondrial homeostasis, and inhibit the development/progression of diabetic retinopathy.

Does bariatric surgery adversely impact on diabetic retinopathy in persons with morbid obesity and type 2 diabetes? A pilot study

AIMS

To assess the incidence and progression of diabetic retinopathy (DR) 12 months post bariatric surgery in persons with morbid obesity and type 2 diabetes.

METHODS

A retrospective pilot analysis of electronic hospital records between 1998 and 2012.

RESULTS

40 of 148 subjects had pre- and post-surgery DR screening. Of those without DR pre-surgery 1.5% (n = 26) progressed to minimum background DR (BDR) post surgery. Those with minimum BDR (n = 9) pre-surgery revealed no progression, with 55.6% (n = 5) showing evidence of regression. One person with moderately severe BDR and two with pre-proliferative DR (PPDR) prior to surgery experienced progression. Two persons with PPDR prior to surgery remained under the hospital eye services and were therefore not eligible to be re-assessed by the screening service.

CONCLUSIONS

There was a low incidence of new DR and progression of DR in those either without evidence of retinopathy or with minimal BDR prior to surgery with some subjects showing evidence of regression. There was however a risk of progression of DR in those with moderate BDR or worse, and should therefore be monitored closely post-surgery.

Evolving strategies in the management of diabetic retinopathy

Diabetic retinopathy (DR), the most common long-term complication of diabetes mellitus, remains one of the leading causes of blindness worldwide. Tight glycemic and blood pressure control has been shown to significantly decrease the risk of development as well as the progression of retinopathy and represents the cornerstone of medical management of DR. The two most threatening complications of DR are diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR). Focal/grid photocoagulation and panretinal photocoagulation are standard treatments for both DME and PDR, respectively. Focal/grid photocoagulation is a better treatment than intravitreal triamcinolone acetonide in eyes with DME. Currently, most experts consider combination focal/grid laser therapy and pharmacotherapy with intravitreal antivascular endothelial growth factor agents in patients with center-involving DME. Combination therapy reduces the frequency of injections needed to control edema. Vitrectomy with removal of the posterior hyaloid seems to be effective in eyes with persistent diffuse DME, particularly in eyes with associated vitreomacular traction. Emerging therapies include fenofibrate, ruboxistaurin, renin-angiotensin system blockers, peroxisome proliferator-activated receptor gamma agonists, pharmacologic vitreolysis, and islet cell transplantation.

Systemic medical management of diabetic retinopathy

Diabetes mellitus (DM) has assumed epidemic proportions and as a consequence, diabetic retinopathy is expected to be a major societal problem across the world. Diabetic retinopathy (DR) affects the vision by way of proliferative disease that results in vitreous hemorrhage and traction retinal detachment or by way of diabetic maculopathy (DME). The present-day management of diabetic retinopathy revolves around screening the diabetics for evidence of retinopathy and treating the retinopathy with laser photocoagulation. DME is treated with laser photocoagulation and/or intra- vitreal injection of anti-vascular endothelial growth factor (VEGF) agents or steroids. Laser remains the mainstay of treatment and is potentially destructive. Systemic management aims at preventing or delaying the onset of retinopathy; reversing the early retinopathy; or delaying the progression of established retinopathy. Evidence from multiple studies has confirmed the protective role of rigid control of blood glucose and blood pressure. The evidence for lipid control versus maculopathy was less definitive. However, the use of fenofibrates (originally used for lowering serum lipids) has shown a benefit on both proliferative disease and maculopathy outside their lipid-lowering effect. Other drugs being tried are the Protein Kinase C (PKC) inhibitors, other peroxisome proliferator-activated receptors (PPAR) agonists, Forsoklin (which binds GLUT 1 receptor), minocycline (for its anti inflammatory effect), and Celecoxib (Cox-2 inhibitor).

Intensive glucose control versus conventional glucose control for type 1 diabetes mellitus

BACKGROUND

Clinical guidelines differ regarding their recommended blood glucose targets for patients with type 1 diabetes and recent studies on patients with type 2 diabetes suggest that aiming at very low targets can increase the risk of mortality.

OBJECTIVES

To assess the effects of intensive versus conventional glycaemic targets in patients with type 1 diabetes in terms of long-term complications and determine whether very low, near normoglycaemic values are of additional benefit.

SEARCH METHODS

A systematic literature search was performed in the databases The Cochrane Library, MEDLINE and EMBASE. The date of the last search was December 2012 for all databases.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that had defined different glycaemic targets in the treatment arms, studied patients with type 1 diabetes, and had a follow-up duration of at least one year.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data, assessed studies for risk of bias, with differences resolved by consensus. Overall study quality was evaluated by the 'Grading of Recommendations Assessment, Development, and Evaluation' (GRADE) system. Random-effects models were used for the main analyses and the results are presented as risk ratios (RR) with 95% confidence intervals (CI) for dichotomous outcomes.

MAIN RESULTS

We identified 12 trials that fulfilled the inclusion criteria, including a total of 2230 patients. The patient populations varied widely across studies with one study only including children, one study only including patients after a kidney transplant, one study with newly diagnosed adult patients, and several studies where patients had retinopathy or microalbuminuria at baseline. The mean follow-up duration across studies varied between one and 6.5 years. The majority of the studies were carried out in the 1980s and all trials took place in Europe or North America. Due to the nature of the intervention, none of the studies could be carried out in a blinded fashion so that the risk of performance bias, especially for subjective outcomes such as hypoglycaemia, was present in all of the studies. Fifty per cent of the studies were judged to have a high risk of bias in at least one other category.Under intensive glucose control, the risk of developing microvascular complications was reduced compared to conventional treatment for a) retinopathy: 23/371 (6.2%) versus 92/397 (23.2%); RR 0.27 (95% CI 0.18 to 0.42); P < 0.00001; 768 participants; 2 trials; high quality evidence; b) nephropathy: 119/732 (16.3%) versus 211/743 (28.4%); RR 0.56 (95% CI 0.46 to 0.68); P < 0.00001; 1475 participants; 3 trials; moderate quality evidence; c) neuropathy: 29/586 (4.9%) versus 86/617 (13.9%); RR 0.35 (95% CI 0.23 to 0.53); P < 0.00001; 1203 participants; 3 trials; high quality evidence. Regarding the progression of these complications after manifestation, the effect was weaker (retinopathy) or possibly not existent (nephropathy: RR 0.79 (95% CI 0.37 to 1.70); P = 0.55; 179 participants with microalbuminuria; 3 trials; very low quality evidence); no adequate data were available regarding the progression of neuropathy. For retinopathy, intensive glucose control reduced the risk of progression in studies with a follow-up duration of at least two years (85/366 (23.2%) versus 154/398 (38.7%); RR 0.61 (95% CI 0.49 to 0.76); P < 0.0001; 764 participants; 2 trials; moderate quality evidence), while we found evidence for an initial worsening of retinopathy after only one year of intensive glucose control (17/49 (34.7%) versus 7/47 (14.9%); RR 2.32 (95% CI 1.16 to 4.63); P = 0.02; 96 participants; 2 trials; low quality evidence).Major macrovascular outcomes (stroke and myocardial infarction) occurred very rarely, and no firm evidence could be established regarding these outcome measures (low quality evidence).We found that intensive glucose control increased the risk for severe hypoglycaemia, however the results were heterogeneous and only the 'Diabetes Complications Clinical Trial' (DCCT) showed a clear increase in severe hypoglycaemic episodes under intensive treatment. A subgroup analysis according to the baseline haemoglobin A1c (HbA1c) of participants in the trials (low quality evidence) suggests that the risk of hypoglycaemia is possibly only increased for patients who started with relatively low HbA1c values (< 9.0%). Several of the included studies also showed a greater weight gain under intensive glucose control, and the risk of ketoacidosis was only increased in studies using insulin pumps in the intensive treatment group (very low quality evidence).Overall, all-cause mortality was very low in all studies (moderate quality evidence) except in one study investigating renal allograft as treatment for end-stage diabetic nephropathy. Health-related quality of life was only reported in the DCCT trial, showing no statistically significant differences between the intervention and comparator groups (moderate quality evidence). In addition, only the DCCT published data on costs, indicating that intensive glucose therapy control was highly cost-effective considering the reduction of potential diabetes complications (moderate quality evidence).

AUTHORS' CONCLUSIONS

Tight blood sugar control reduces the risk of developing microvascular diabetes complications. The evidence of benefit is mainly from studies in younger patients at early stages of the disease. Benefits need to be weighed against risks including severe hypoglycaemia, and patient training is an important aspect in practice. The effects of tight blood sugar control seem to become weaker once complications have been manifested. However, further research is needed on this issue. Furthermore, there is a lack of evidence from RCTs on the effects of tight blood sugar control in older patient populations or patients with macrovascular disease. There is no firm evidence for specific blood glucose targets and treatment goals need to be individualised taking into account age, disease progression, macrovascular risk, as well as the patient's lifestyle and disease management capabilities.

Current trends in the monitoring and treatment of diabetic retinopathy in young adults

The diagnosis and treatment of diabetic retinopathy (DR) in young adults have significantly improved in recent years. Research methods have widened significantly, for example, by introducing spectral optical tomography of the eye. Invasive diagnostics, for example, fluorescein angiography, are done less frequently. The early introduction of an insulin pump to improve the administration of insulin is likely to delay the development of diabetic retinopathy, which is particularly important for young patients with type 1 diabetes mellitus (T1DM). The first years of diabetes occurring during childhood and youth are the most appropriate to introduce proper therapeutic intervention before any irreversible changes in the eyes appear. The treatment of DR includes increased metabolic control, laserotherapy, pharmacological treatment (antiangiogenic and anti-inflammatory treatment, enzymatic vitreolysis, and intravitreal injections), and surgery. This paper summarizes the up-to-date developments in the diagnostics and treatment of DR. In the literature search, authors used online databases, PubMed, and clinitrials.gov and browsed through individual ophthalmology journals, books, and leading pharmaceutical company websites.

Diabetic retinopathy and other ocular findings in the diabetes control and complications trial/epidemiology of diabetes interventions and complications study

OBJECTIVE To evaluate whether intensive treatment (INT) with the goal of achieving blood glucose levels as close to the nondiabetic range as safely possible reduced the risk of onset and progression of diabetic retinopathy (DR) in subjects with type 1 diabetes (T1D) compared with conventional therapy (CON). RESEARCH DESIGN AND METHODS The Diabetes Control and Complications Trial (DCCT) (1982-1993) was a multicenter, controlled clinical trial comparing INT with CON for onset and progression of DR. The Epidemiology of Diabetes Interventions and Complications (EDIC) study (1994-present) is an observational follow-up of the DCCT cohort. RESULTS Of the 1,441 DCCT subjects, 726 had no DR (primary prevention cohort) and 715 had mild DR (secondary intervention cohort) at baseline. Subjects were followed for a mean of 6.5 years. INT median HbA1c was 7% compared with CON median of 9%. INT reduced the adjusted mean risk for the development of DR by 76% and slowed progression of DR by 54% compared with CON. Following DCCT, the HbA1c levels in the original INT and CON groups converged (year 8, INT 7.98%; CON 8.07%); nevertheless, the groups continued to have a durable effect of initial assigned therapy with significantly lower incidence of further DR progression in the INT group (hazard reduction 53-56%). Severe retinal outcomes and procedures to treat them were reduced by 50% in the original INT group. CONCLUSIONS INT delays the onset and slows the progression of DR. Furthermore, the early effects of metabolic control continue to accrue over many years despite subsequent comparable glycemic control (metabolic memory). These results emphasize the need for optimizing glycemic control as early as possible in patients with diabetes.

Impact of changes in metabolic control on progression to photocoagulation for clinically significant macular oedema: a 20 year study of type 1 diabetes

AIMS/HYPOTHESIS

Although increasing hyperglycaemia, arterial hypertension and longer duration of diabetes raise the risk of progression of diabetic retinopathy, short-term benefits in terms of improved metabolic control and lowered blood pressure have not been demonstrated. We therefore examined the effect of changes in glycaemia and arterial blood pressure on the incidence of clinically significant macular oedema in a population of diabetic patients.

METHODS

We performed a retrospective review of all patients with type 1 diabetes who attended the retinopathy screening clinic at the Steno Diabetes Center from 1988 to 2008, using the endpoint referral to first photocoagulation treatment for clinically significant diabetic macular oedema. The analysis included 1,878 patients (median observation, 8 years). Changes were defined as the inter-visit change; in the case of an event the last event-free interval before referral, where the median screening interval was 6 months.

RESULTS

Risk of progression to photocoagulation for macular oedema increased with duration of diabetes (p < 0.001), current HbA1c (p < 0.0001) and with the magnitude of changes in HbA1c (p = 0.0002) and systolic blood pressure (p < 0.0001) in a multiple regression model. A recent decrease of ≥ 0.5 percentage points or an increase in HbA1c of >0.5 percentage points per 6 months was associated with HRs of 3.04 and 1.28, respectively, compared with lesser changes in HbA1c.

CONCLUSIONS/INTERPRETATION

In this study, large recent changes in metabolic control and systolic blood pressure, irrespective of direction, were independent risk factors for progression to photocoagulation for diabetic macular oedema. The effects of metabolic and haemodynamic stability on diabetic retinopathy should be examined in prospective studies.

Severe worsening of diabetic retinopathy following bariatric surgery

Intensive glycemic control results in long-term reduction of diabetic retinopathy, although initial short-term worsening of retinopathy is not uncommon. The authors report a patient with a history of stable diabetic retinopathy who, despite achieving abrupt glycemic control following laparoscopic Roux-en-Y gastric bypass surgery, suffered rapid worsening of her retinopathy within 1 month of surgery. Hemoglobin A1c levels were 8.8 preoperatively and declined to 7.2 at 3.5 months postoperatively. Although visual function in the left eye was spared, useful visual acuity was lost in the right eye. Retinal evaluation is recommended in all patients with diabetes mellitus who are considering bariatric surgery, with close follow-up as warranted.

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.

HbA1c variability as an independent correlate of nephropathy, but not retinopathy, in patients with type 2 diabetes: the Renal Insufficiency And Cardiovascular Events (RIACE) Italian multicenter study

OBJECTIVE

To examine the association of hemoglobin (Hb) A1c variability with microvascular complications in the large cohort of subjects with type 2 diabetes from the Renal Insufficiency And Cardiovascular Events (RIACE) Italian Multicenter Study.

RESEARCH DESIGN AND METHODS

Serial (3-5) HbA1c values collected in a 2-year period before enrollment were available from 8,260 subjects from 9 centers (of 15,773 patients from 19 centers). HbA1c variability was measured as the intraindividual SD of 4.52 ± 0.76 values. Diabetic retinopathy (DR) was assessed by dilated funduscopy. Chronic kidney disease (CKD) was defined based on albuminuria, as measured by immunonephelometry or immunoturbidimetry, and estimated glomerular filtration rate (eGFR) was calculated from serum creatinine.

RESULTS

Median and interquartile range of average HbA1c (HbA1c-MEAN) and HbA1c-SD were 7.57% (6.86-8.38) and 0.46% (0.29-0.74), respectively. The highest prevalence of microalbuminuria, macroalbuminuria, reduced eGFR, albuminuric CKD phenotypes, and advanced DR was observed when both HbA1c parameters were above the median and the lowest when both were below the median. Logistic regression analyses showed that HbA1c-SD adds to HbA1c-MEAN as an independent correlate of microalbuminuria and stages 1-2 CKD and is an independent predictor of macroalbuminuria, reduced eGFR, and stages 3-5 albuminuric CKD, whereas HbA1c-MEAN is not. The opposite was found for DR, whereas neither HbA1c-MEAN nor HbA1c-SD affected nonalbuminuric CKD.

CONCLUSIONS

In patients with type 2 diabetes, HbA1c variability affects (albuminuric) CKD more than average HbA1c, whereas only the latter parameter affects DR, thus suggesting a variable effect of these measures on microvascular complications.

Pregnancy-associated retinal diseases and their management

Pregnancy-associated retinal diseases are conditions that may occur uniquely in pregnancy or, more commonly, general conditions that may worsen or alter during pregnancy as a result of hematologic, hormonal, metabolic, cardiovascular, and immunologic changes. Diabetic retinopathy (DR) is by far the most common retinal condition that is altered by pregnancy. However, there are currently no widely accepted, precise clinical guidelines regarding its management during pregnancy. At present it is not possible to predict who will regress and who will progress without treatment. Some of the variation in progression of DR in pregnancy may be a result of well-known risk factors such as hypertension or inadequate glycemic control prior to pregnancy. Other pregnancy-associated retinal diseases are relatively uncommon, and their treatments are poorly characterized. Pre-existing conditions include the white dot syndromes, such as punctuate inner choroidopathy and ocular histoplasmosis syndrome, as well as chorioretinal neovascularization from many other etiologies. Retinal and chorioretinal disorders that can arise during pregnancy include central serous chorioretinopathy and occlusive vasculopathy such as retinal artery occlusion (Purtschers-like retinopathy) and retinal vein occlusion. There remains a small group that appear to be unique to pregnancy, with pre-eclampsia- and eclampsia-associated retinopathy, disseminated intravascular coagulopathy, or amniotic fluid embolism being the best described. In angiogenic retinal diseases outside of pregnancy, the use of anti-vascular endothelial growth factor (anti-VEGF agents) has proven helpful. There are no safety data about the use of anti-VEGF agents during pregnancy, and conventionally the proposed interventions have been laser photocoagulation and systemic or intravitreal injections of steroids. Most of the literature on the treatment of pregnancy associated-chorioretinal neovascularization is anecdotal.

Euglycemic progression: worsening of diabetic retinopathy in poorly controlled type 2 diabetes in minorities

AIMS

In type 2 diabetes, early effects of strict near-normalization of glucose control on macrovascular and microvascular disease are still uncertain. We evaluated the effects of early dramatic improvement in glycemia on retinal disease in poorly controlled diabetes.

METHODS

A retrospective, case-control study in public hospital patients with type 2 diabetes, who had annual retinal imaging as part of a case management program or standard diabetes care. Patients included had ≥2 two retinal images ≥1 one year apart, and at least 3 HbA1C measurements. Retinal images were graded using a modified Scottish Diabetic Retinopathy grading scheme. An 'intensive' group (n=34) with HbA1C decrease >1.5% was compared with randomly chosen patients (n=34) with minimal HbA1C changes.

RESULTS

Mean HbA1C (±SEM) over two years was similar in intensive (8.5 ± 0.21%) and control groups (8.1 ± 0.28%, p=NS). However, the intensive group had higher baseline HbA1C and a mean maximal decrease of 4.0 ± 0.41% in contrast to the control group (0.2 ± 0.11%). Retinopathy grade progressed +0.7 ± 0.25 units from baseline in the intensive group (p=0.015), a 22.6% worsening. The control group changed minimally from baseline (0.03 ± 0.14 units, p=NS). Change in retinopathy grade was significantly different between groups (p=0.02). More eyes worsened by ≥ 1 retinal grade (p=0.0025) and developed sight-threatening retinopathy (p=0.003) in the intensive group. Visual acuity was unchanged.

CONCLUSIONS

Diabetic retinopathy significantly worsened in poorly controlled type 2 diabetes after early intensification of glycemic control and dramatic HbA1C change. Retinal status should be part of risk-factor evaluation in patients likely to experience marked reductions in HbA1C in poorly controlled diabetes.

Optimal treatment of diabetic retinopathy

Diabetic retinopathy (DRP) is a common complication caused by multiple biochemical abnormalities of the underlying metabolic disease. While the incidence of DRP appears to decline due to evidence-based changes in diabetes management, the predicted increase in patients affected in particular by type 2 diabetes may outweigh the positive trend. The diagnosis is based on the alterations of the vessels, usually indicating abnormalities of the blood-retinal barrier and increased vasoregression, but the neuroglial elements appear equally vulnerable to the diabetic condition. Control of blood glucose, blood pressure and timely identification of coincident nephropathy are important to prevent progression to vision-threatening stages. Guidelines give specific indications for laser photocoagulation, in particular when euglycemia is no longer effective in preventing progression to advanced stages. Intravitreal administration of antibodies directed against the single best characterized propagator of clinically significant macular edema, vascular endothelial growth factor (VEGF), has become popular despite uncertainty about the patient subgroups which benefit best and the optimum administration schedule. Multifactorial intervention beyond glycemic control includes antihypertensive, lipid-lowering and antiaggregatory and is effective in type 2 diabetic patients with high-risk profiles, in particular coincident nephropathy.

Epigenetic modification of Sod2 in the development of diabetic retinopathy and in the metabolic memory: role of histone methylation

PURPOSE

Mitochondrial superoxide levels are elevated in the retina in diabetes, and their scavenging enzyme, MnSOD, becomes subnormal. The objective of this study is to investigate the role of histone methylation of Sod2, the gene that encodes MnSOD, in the development of diabetic retinopathy and in the metabolic memory phenomenon associated with its continued progression after termination of hyperglycemia.

METHODS

Effect of high glucose on monomethyl H3K4 (H3K4me1), dimethyl H3K4 (H3K4me2), and lysine-specific demethylase-1 (LSD1) was quantified at Sod2 by chromatin immunoprecipitation in isolated retinal endothelial cells. The role of histone methylation in the metabolic memory phenomenon was investigated in the retina of rats maintained in poor glycemic control (PC, approximately 12% glycated hemoglobin [GHb]) for 3 months followed by in good glycemic control (GC, approximately 6% GHb) for 3 months.

RESULTS

Hyperglycemia reduced H3K4me1 and -me2, and increased the binding of LSD1 and Sp1 at Sod2. Regulation of LSD1 by LSD1-siRNA ameliorated glucose-induced decrease in H3K4 methylation at Sod2, and prevented decrease in Sod2 gene expression. In rats, re-institution of GC failed to reverse decrease in H3K4me1 and -me2 at Sod2, and LSD1 remained active with increased binding of LSD1 and Sp1 at Sod2. Retina from human donors with diabetic retinopathy also had decreased H3K4me2 and increased LSD1 at Sod2.

CONCLUSIONS

Histone methylation of retinal Sod2 has an important role in the development of diabetic retinopathy and in the metabolic memory phenomenon associated with its continued progression. Targeting enzymes important for histone methylation may serve as a potential therapy to halt the development of diabetic retinopathy.

Retinopathy in diabetes

With the incidence, and prevalence of diabetes mellitus increasing worldwide, diabetic retinopathy is expected to reach epidemic proportions. The aim of this chapter is to introduce diabetic retinopathy, a leading cause of blindness in people of the working age. The clinical course of retinopathy, anatomical changes, its pathogenesis and current treatment are described, followed by an overview of the emerging drug therapies for the potential treatment of this sight-threatening complication of diabetes.

[Diagnosis, therapy and follow up of diabetic eye disease]

Diabetes mellitus causes diabetic retinopathy, diabetic macular edema, optic neuropathy, cataract or dysfunction of the eye muscles. The incidence of these defects correlates with disease duration and quality of the metabolic control. The recommendations of the Austrian Diabetes Association for the diagnosis, the therapeutic procedures and requirements for adequate follow up depending on the stages of the different forms of diabetic eye disease are summarized.

Current trends in the pharmacotherapy of diabetic retinopathy

Diabetic retinopathy (DR) is one of the most debilitating disorders of microvasculature of the retina and one of the leading causes of vision loss among the working class worldwide. At present, intravitreal anti-inflammatory (corticosteroids) and anti-angiogenesis (anti-Vascular Endothelial Growth Factor) agents are being used as wide options for the pharmacotherapy of DR and diabetic macular edema (DME). Anti-inflammatory agents (Triamcinolone acetonide and other agents) have shown evidence-based clinical benefits in various randomized clinical trials for the treatment of DR and DME, and also shown improvement in best corrected visual acuity. However, direct intravitreal injections are associated with serious side-effects like cataract and elevation of Intra Ocular Pressure. Despite this, corticosteroid therapy has been effective for DR and DME, therefore current focus is on the development of novel intravitreal steroid delivery devices that release a small quantity over a prolonged period of time. In addition to corticosteroids, anti-angiogenic agents are found to be effective for the treatment of DR and DME. The most popular target of these agents is the subfamily of proteins known as VEGF, whose over-expression is believed to play a role in numerous diseases including DR and Age-related Macular Degeneration. Intravitreal bevacizumab (Avastin®) and Ranibizumab (Lucentis®) are gaining popularity as a clinical adjunct to panretinal photocoagulation in patients with proliferative DR. Moreover, Lucentis has been recently approved by the United States Food and Drug Administration for macular edema following retinal vein occlusion. Further, systemic agents (specially, hypoglycemic, hypolipidemic and anti-hypertensive agents) have shown beneficial results in reducing the progression of DR. In conclusion, it can be stated that for the present scenario systematic use of available pharmacotherapy as an adjunct to laser photocoagulation, which is gold standard therapy, can be a useful tool in the prevention of vision loss from DR and related disorders. This article summarizes the up-to-date developments in the pharmacotherapy of DR. Method- Literature search was done on online database, Pubmed, Google Scholar, clinitrials.gov and browsing through individual ophthalmology journals and leading pharmaceutical company websites.

Current epidemiology of diabetic retinopathy and diabetic macular edema

With increasing global prevalence of diabetes, diabetic retinopathy (DR) is set to be the principle cause of vision impairment in many countries. DR affects a third of people with diabetes and the prevalence increases with duration of diabetes, hyperglycemia, and hypertension-the major risk factors for the onset and progression of DR. There are now increasing data on the epidemiology of diabetic macular edema (DME), an advanced complication of DR, with studies suggesting DME may affect up to 7 % of people with diabetes. The risk factors for DME are largely similar to DR, but dyslipidemia appears to play a more significant role. Early detection of DR and DME through screening programs and appropriate referral for therapy is important to preserve vision in individuals with diabetes. Future research is necessary to better understand the potential role of other risk factors such as apolipoproteins and genetic predisposition to shape public health programs.

The rise and fall of HbA(1c) as a risk marker for diabetes complications

It is still unclear whether short-term, within-day, variability in glycaemic control is contributory to the development of diabetes micro- or macrovascular complications. However, consistent and compelling data are emerging that longer term fluctuations in glucose, as evidenced by increases in HbA(1c) variability, do indeed add to the mean HbA(1c) value in predicting the risk of microvascular disease. Until now, studies have found this to be the case mainly in type 1 diabetes, but in this issue of Diabetologia (DOI: 10.1007/s00125-012-2572-7 ) an analysis of the Tsukuba Kawai Diabetes Registry in Japan has found that HbA(1c) variability also predicts the risk of nephropathy in type 2 diabetic patients. These observations raise the possibility that reducing rises and falls in HbA(1c) may help avoid hyperglycaemia-related vascular disease without running the same risk of hypoglycaemia that a strategy focusing purely on lower HbA(1c) might incur.

A crossover comparison of glycemic variations in Japanese patients with type 1 diabetes receiving insulin glargine versus insulin detemir twice daily using continuous glucose monitoring (CGM): J COLLECTION (Jikei COmparison of Lantus and LEvemir with Cgm for Thinking Insulin OptimizatioN)

BACKGROUND

This study aimed to compare glycemic variations seen among Japanese patients with type 1 diabetes treated with insulin glargine versus insulin detemir using continuous glucose monitoring (CGM) in a crossover design.

SUBJECTS AND METHODS

Twenty-three patients with type 1 diabetes were enrolled in this study. The subjects were on either insulin glargine followed by insulin detemir twice daily, or vice versa, with no change in the timing of injections. The glycemic variations during 4-day hospitalizations were monitored by CGM while the patients were on either regimen, with a second hospitalization scheduled more than 1 month after the change of the long-acting insulin analogs. CGM data obtained on Day 3 of both hospitalizations were compared.

RESULTS

The subjects had a median age of 44.0 years, a median body mass index of 22.2 kg/m(2), and a median glycosylated hemoglobin of 7.3%. There was no significant difference between the two treatments with a mean glucose level of 156 mg/dL with the insulin glargine treatment versus 150 mg/dL with the insulin detemir treatment; their SD values were 60 versus 51 mg/dL, their mean amplitude of glycemic excursions values were 121 versus 105 mg/dL, and their mean of daily differences values were 45.7 versus 41.4 mg/dL, respectively. In addition, the insulin detemir treatment was associated with a narrower range of postprandial glucose increases after lunch (80 vs. 59 mg/dL; P=0.007).

CONCLUSIONS

A comparison of the long-acting insulin analogs administered twice daily in type 1 diabetes demonstrated that insulin detemir may potentially offer better glycemic control after lunch than insulin glargine.

Impact of hypoglycemia associated with antihyperglycemic medications on vascular risks in veterans with type 2 diabetes

OBJECTIVE

Hypoglycemia is associated with failure to show cardiovascular benefit and increased mortality of intensive glycemic control in randomized clinical trials. This retrospective cohort study aimed to examine the impact of hypoglycemia on vascular events in clinical practice.

RESEARCH DESIGN AND METHODS

Patients with type 2 diabetes were identified by ICD-9-CM codes (250.xx except for 250.x1 and 250.x3) between 1 January 2004 and 1 September 2010 from the Veterans Integrated Service Network 16. Index date was defined as the first date of new antihyperglycemic medications (index treatment). Patients with 1-year preindex records of hypoglycemia, cardiovascular, and microvascular diseases were excluded. The hypoglycemia group was identified by ICD-9-CM codes (250.8, 251.0, 251.1, and 251.2) within the index treatment period. A propensity score-matched group was used as control subjects. Cardiovascular events, microvascular complications, and all-cause death were compared using Kaplan-Meier analysis and Cox proportional hazards regression model.

RESULTS

Among the unmatched sample (N = 44,261), the hypoglycemia incidence rate was 3.57/100 patient-years. The matched sample (hypoglycemia group: n = 761; control group: n = 761) had a median follow-up of 3.93 years, mean age of 62.6 ± 11.0 years, and preindex HbA(1c) of 10.69 ± 2.61%. The 1-year change in HbA(1c) was similar (hypoglycemia group -0.51 vs. control group -0.32%, P = 0.7244). The hypoglycemia group had significantly higher risks of cardiovascular events (hazard ratio 2.00 [95% CI 1.63-2.44]) and microvascular complications (1.76 [1.46-2.11]) but no statistical mortality difference. Patients with at least two hypoglycemic episodes were at higher risks of vascular events than those with one episode (1.53 [1.10-1.66]).

CONCLUSIONS

Hypoglycemia is associated with higher risks of incident vascular events. Patients with hypoglycemia should be monitored closely for vascular events.

Matrix metalloproteinases in diabetic retinopathy: potential role of MMP-9

INTRODUCTION

Diabetic retinopathy remains one of the most feared complications of diabetes. Despite extensive research in the field, the molecular mechanism responsible for the development of this slow progressing disease remains unclear. In the pathogenesis of diabetic retinopathy, mitochondria are damaged and inflammatory mediators are elevated before the histopathology associated with the disease can be observed. Matrix metalloproteinases (MMPs) regulate a variety of cellular functions including apoptosis and angiogenesis. Diabetic environment stimulates the secretion of several MMPs that are considered to participate in complications, including retinopathy, nephropathy and cardiomyopathy. Patients with diabetic retinopathy and also animal models have shown increased MMP-9 and MMP-2 in their retina and vitreous. Recent research has shown that MMPs have dual role in the development of diabetic retinopathy; in the early stages of the disease (pre-neovascularization), MMP-2 and MMP-9 facilitate the apoptosis of retinal capillary cells, possibly via damaging the mitochondria, and in the later phase, they help in neovascularization.

AREAS COVERED

This article reviews the literature to evaluate the role of MMPs, especially MMP-9, in the development of diabetic retinopathy, and presents existing evidence that the inhibitors targeted toward MMP-9, depending on the duration of diabetes at the times their administration could have potential to prevent the progression of this blinding disease, and protect the vision loss.

EXPERT OPINION

Inhibitors of MMPs could have dual role: in the early stages of the diseases, inhibit capillary cell apoptosis, and if the disease has progressed to the angiogenic stage, inhibit the growth of new vessels.

Telehealth practice recommendations for diabetic retinopathy, second edition

Ocular telemedicine and telehealth have the potential to decrease vision loss from DR. Planning, execution, and follow-up are key factors for success. Telemedicine is complex, requiring the services of expert teams working collaboratively to provide care matching the quality of conventional clinical settings. Improving access and outcomes, however, makes telemedicine a valuable tool for our diabetic patients. Programs that focus on patient needs, consider available resources, define clear goals, promote informed expectations, appropriately train personnel, and adhere to regulatory and statutory requirements have the highest chance of achieving success.

Potential Therapeutic Roles for Inhibition of the PI3K/Akt/mTOR Pathway in the Pathophysiology of Diabetic Retinopathy

Novel therapeutics such as inhibitors of PI3K/Akt/mTOR pathway presents a unique opportunity for the management of diabetic retinopathy (DR). Second generation mTOR inhibitors have the prospect to be efficacious in managing various stages of disease progression in DR. During early stages, the mTOR inhibitors suppress HIF-1α, VEGF, leakage, and breakdown of the blood-retinal barrier. These mTOR inhibitors impart a pronounced inhibitory effect on inflammation, an early component with diverse ramifications influencing the progression of DR. These inhibitors suppress IKK and NF-κB along with downstream inflammatory cytokines, chemokines, and adhesion molecules. In proliferative DR, mTOR inhibitors suppress several growth factors that play pivotal roles in the induction of pathological angiogenesis. Lead mTOR inhibitors in clinical trials for ocular indications present an attractive treatment option for chronic use in DR with favorable safety profile and sustained ocular pharmacokinetics following single dose. Thereby, reducing dosing frequency and risk associated with chronic drug administration.

Retinal function in relation to improved glycaemic control in type 1 diabetes

AIMS/HYPOTHESIS

To study long-term changes in retinal function in response to sustained glycaemia reduction in participants with type 1 diabetes.

METHODS

Prospective study using objective measures of retinal function in 17 participants with type 1 diabetes mellitus and minimal to moderate retinopathy who switched from conventional subcutaneous injection to continuous subcutaneous infusion of insulin (CSII).

RESULTS

Glycated haemoglobin HbA(1c) gradually decreased from 9.1% at baseline before CSII to 7.4% after 1 year on CSII. Glycaemia was markedly reduced within 1 week after initiation of CSII and remained stable thereafter. Dark adaptation and retinal electroretinographic function at 1, 4 and 16 weeks after initiation of CSII were comparable with baseline values, whereas a significant improvement in rod photoreceptor dark adaptation and dark-adapted b-wave amplitudes were seen after 52 weeks (time to rod-cone break -25% [p < 0.0001], time to a standardised rod intercept -13% [p < 0.0001], dark-adapted rod b-wave full-field amplitude +15% [p = 0.0125], standard combined rod-cone b-wave amplitude +8% [p = 0.049]). No detectable change was observed in cone adaptation, electroretinographic cone function or retinopathy.

CONCLUSIONS/INTERPRETATION

After initiation of CSII, the retinal visual pathway of the rods improved with a delay of more than 4 months, over a time scale comparable with the duration of the diabetic retinopathy early worsening response to sustained glycaemia reduction. This indicates that glycaemia has a long-term effect on the disposition of functional capacity in the retinal visual pathway of rod photoreceptors, the cells that appear to be driving the development of diabetic retinopathy.

Diabetic retinopathy: pathogenic mechanisms and current treatments

Since diabetes is now a global epidemic, the incidence of retinopathy, a leading cause of blindness in patients aged 20-74 years, is also expected to rise to alarming levels. The risk of development and progression of diabetic retinopathy is closely associated with the type and duration of diabetes, blood glucose, blood pressure and possibly lipids. It is an unmet medical need that can lead to severe and irreversible loss of vision in people of working age worldwide. The aim of this review is to give an overview of the clinical and anatomical changes during the progression of retinopathy, the underlying pathogenic mechanisms that link hyperglycemia with retinal tissue damage, current treatments, and the emerging pharmacological therapies for this sight-threatening complication of diabetes.

Diabetic retinopathy - An update

Management of diabetes should involve both systemic and ocular aspects. Control of hyperglycemia, hypertension and dyslipidemia are of major role in the management of diabetic retinopathy. In the ocular part; laser treatment remains the cornerstone of treatment of diabetic macular edema (focal/grid), severe non-proliferative and proliferative diabetic retinopathy (panretinal photocoagulation). There is a strong support to combination therapy. Using one or two intravitreal injections such as anti-VEGF and or steroid to reduce central macular thickness followed by focal or grid laser to give a sustained response may offer an alternative to treatment in diabetic macular edema. Anti-VEGF were found to be effective as an adjunct therapy in proliferative diabetic retinopathy patient who is going to have vitrectomy for vitreous hemorrhage with neovascularization, panretinal photocoagulation, and other ocular surgery such as cases with neovascular glaucoma and cataract with refractory macular edema.

Advances in the treatment of diabetic retinopathy

Diabetic retinopathy, the most common long-term complication of diabetes mellitus, remains one of the leading causes of blindness worldwide. Strict metabolic control, tight blood pressure control, laser photocoagulation, and vitrectomy remain the standard care for diabetic retinopathy. Focal/grid photocoagulation is a better treatment than intravitreal triamcinolone acetonide in eyes with diabetic macular edema and should be considered as the first-line therapeutic option. The current evidence suggests that intravitreal triamcinolone acetonide or anti-vascular endothelial growth factor agents result in a temporary improvement of visual acuity and a short-term reduction in central macular thickness in patients with refractory diabetic macular edema and are an effective adjunctive treatments to laser photocoagulation or vitrectomy. However, triamcinolone is associated with risks of elevated intraocular pressure and cataract. Vitrectomy with the removal of the posterior hyaloid without internal limiting membrane peeling seems to be effective in eyes with persistent diffuse diabetic macular edema, particularly in eyes with associated vitreomacular traction. Emerging therapies include islet cell transplantation, fenofibrate, ruboxistaurin, pharmacologic vitreolysis, rennin-angiotensin system blockers, and peroxisome proliferator-activated receptor gamma agonists.

Diabetic retinopathy, superoxide damage and antioxidants

Retinopathy, the leading cause of acquired blindness in young adults, is one of the most feared complications of diabetes, and hyperglycemia is considered as the major trigger for its development. The microvasculature of the retina is constantly bombarded by high glucose, and this insult results in many metabolic, structural and functional changes. Retinal mitochondria become dysfunctional, its DNA is damaged and proteins encoded by its DNA are decreased. The electron transport chain system becomes compromised, further producing superoxide and providing no relief to the retina from a continuous cycle of damage. Although the retina attempts to initiate repair mechanisms by inducing gene expressions of the repair enzymes, their mitochondrial accumulation remains deficient. Understanding the molecular mechanism of mitochondrial damage should help identify therapies to treat/retard this sight threatening complication of diabetes. Our hope is that if the retinal mitochondria are maintained healthy with adjunct therapies, the development and progression of diabetic retinopathy can be inhibited.