Microvascular complications. Retinopathy and nephropathy

Association between albuminuria and retinal microvascular parameters measured with swept-source optical coherence tomography angiography in patients with diabetic retinopathy

PURPOSE

To evaluate the relationship between urine albumin excretion (UAE) and retinal microvascular parameters assessed using swept-source optical coherence tomography angiography (SS-OCTA) in patients with diabetic retinopathy (DR).

METHODS

This retrospective cross-sectional study included 180 patients with diabetes and 50 age-matched controls. Patients with diabetes were grouped according to the five-stage DR severity, combined with the presence of albuminuria. All subjects underwent 12×12mm2 field SS-OCTA. The foveal avascular zone metrics, vessel density, and capillary nonperfusion area (NPA) were quantified using a semi-automatic software algorithm on three different rectangular fields (3×3 mm2, 6×6 mm2, and 10×10 mm2). The correlations between albuminuria and the four OCTA parameters were analyzed.

RESULTS

A total of 105 subjects had normal UAE, and 75 subjects had albuminuria. Of the 102 subjects whose DR severity was higher than mild non-proliferative DR (NPDR), capillary NPA on the 3×3 mm2, 6×6 mm2, and 10×10 mm2 fields was significantly larger in the albuminuria group. None of the OCTA parameters were significantly different between the two groups in subjects with mild NPDR or without DR. Multiple logistic regression analysis showed that an increase in NPA in the 6×6 mm2 and 10×10 mm2 fields was a significant risk factor for the presence of albuminuria (odds ratio = 1.92 and 1.35).

CONCLUSION

An increase in capillary NPA was independently associated with albuminuria in patients with clinically significant DR levels. SS-OCTA imaging can be a useful marker for the early detection of diabetic nephropathy.

Parallelism and non-parallelism in diabetic nephropathy and diabetic retinopathy

Diabetic nephropathy (DN) and diabetic retinopathy (DR), as microvascular complications of diabetes mellitus, are currently the leading causes of end-stage renal disease (ESRD) and blindness, respectively, in the adult working population, and they are major public health problems with social and economic burdens. The parallelism between the two in the process of occurrence and development manifests in the high overlap of disease-causing risk factors and pathogenesis, high rates of comorbidity, mutually predictive effects, and partial concordance in the clinical use of medications. However, since the two organs, the eye and the kidney, have their unique internal environment and physiological processes, each with specific influencing molecules, and the target organs have non-parallelism due to different pathological changes and responses to various influencing factors, this article provides an overview of the parallelism and non-parallelism between DN and DR to further recognize the commonalities and differences between the two diseases and provide references for early diagnosis, clinical guidance on the use of medication, and the development of new drugs.

Diabetic retinopathy as the leading cause of blindness and early predictor of cascading complications-risks and mitigation

Proliferative diabetic retinopathy (PDR) the sequel of diabetic retinopathy (DR), a frequent complication of diabetes mellitus (DM), is the leading cause of blindness in the working-age population. The current screening process for the DR risk is not sufficiently effective such that often the disease is undetected until irreversible damage occurs. Diabetes-associated small vessel disease and neuroretinal changes create a vicious cycle resulting in the conversion of DR into PDR with characteristic ocular attributes including excessive mitochondrial and retinal cell damage, chronic inflammation, neovascularisation, and reduced visual field. PDR is considered an independent predictor of other severe diabetic complications such as ischemic stroke. A "domino effect" is highly characteristic for the cascading DM complications in which DR is an early indicator of impaired molecular and visual signaling. Mitochondrial health control is clinically relevant in DR management, and multi-omic tear fluid analysis can be instrumental for DR prognosis and PDR prediction. Altered metabolic pathways and bioenergetics, microvascular deficits and small vessel disease, chronic inflammation, and excessive tissue remodelling are in focus of this article as evidence-based targets for a predictive approach to develop diagnosis and treatment algorithms tailored to the individual for a cost-effective early prevention by implementing the paradigm shift from reactive medicine to predictive, preventive, and personalized medicine (PPPM) in primary and secondary DR care management.

Research Progress on the Positive and Negative Regulatory Effects of Rhein on the Kidney: A Review of Its Molecular Targets

Currently, both acute kidney injury (AKI) and chronic kidney disease (CKD) are considered to be the leading public health problems with gradually increasing incidence rates around the world. Rhein is a monomeric component of anthraquinone isolated from rhubarb, a traditional Chinese medicine. It has anti-inflammation, anti-oxidation, anti-apoptosis, anti-bacterial and other pharmacological activities, as well as a renal protective effects. Rhein exerts its nephroprotective effects mainly through decreasing hypoglycemic and hypolipidemic, playing anti-inflammatory, antioxidant and anti-fibrotic effects and regulating drug-transporters. However, the latest studies show that rhein also has potential kidney toxicity in case of large dosages and long use times. The present review highlights rhein's molecular targets and its different effects on the kidney based on the available literature and clarifies that rhein regulates the function of the kidney in a positive and negative way. It will be helpful to conduct further studies on how to make full use of rhein in the kidney and to avoid kidney damage so as to make it an effective kidney protection drug.

Microvascular changes at different stages of chronic kidney disease

Patients with progressing chronic kidney disease (CKD) are more likely to experience cardio‐ and cerebrovascular events than progressing to end‐stage renal disease. The authors explored whether retinal microvascular calibers differed with the degree of renal impairment and between the standard and extended optic disk and may serve as a simple additional tool for risk stratification in this highly vulnerable patient cohort. The authors analyzed central retinal arteriolar and venular equivalent calibers (CRAE, CRVE) at different retinal zones (zone B&C) using digital retinal imaging in hypertensive patients with stage 2 (n = 66) or stage 3 CKD (n = 30). Results were adjusted for age, sex, HbA1c, and 24‐hour diastolic blood pressure. Mean eGFR was 77.7 ± 8.9 and 48.8 ± 7.9 ml/min/1.73 m² for stage 2 and 3 CKD, respectively. CRAE and CRVE in zones B and C were significantly lower in patients with stage 3 CKD compared to patients with stage 2 CKD (CRAE‐B:141.1 ± 21.4 vs. 130.5 ± 18.9 µm, p = .030; CRAE‐C:137.4 ± 19.4 vs 129.2 ± 18.2 µm, p = .049; CRVE‐B:220.8 ± 33.0 vs. 206.0 ± 28.4 µm, p = .004; and CRVE‐C:215.9 ± 33.0 vs. 201.2 ± 25.1µm, p = .003). In patients with stage 2 CKD, CRAE‐B was higher than CRAE‐C (141.1 ± 21.4 vs. 137.4 ± 19.4µm, p < .001). In contrast, such a difference was not found in patients with stage 3 CKD. CRAE of both retinal zones correlated with eGFR for the entire cohort. In patients with stage 3 CKD, retinal narrowing is more pronounced compared to patients with stage 2 CKD. Whether the novel observation of difference in arteriolar caliber between zones B and C in stage 2 CKD could serve as an early marker of CKD progression warrants further investigation.

Macular Optical Coherence Tomography Angiography in Nephropathic Patients with Diabetic Retinopathy in Iran: A Prospective Case–Control Study

Background

Diabetic macular ischemia (DMI) is an important category of diabetic retinopathy (DR) which leads to severe visual loss. Clinically, it is defined by an enlargement of the foveal avascular zone (FAZ) that can be detected by optical coherence tomography angiography (OCTA). Studies have described a relationship between renal disease and these changes in FAZ area. The aim of this study was to compare disturbances in FAZ area in diabetic patients with or without overt nephropathy.

Methods

Following approval of the ethics committee, we examined diabetic patients with retinopathy. Patients were divided into two groups of DR, namely, with overt nephropathy and without overt nephropathy. The FAZ area was measured using OCTA. A P value of < 0.05 was considered to be statistically significant.

Result

A total of 46 patients (78 eyes) were enrolled in this study. All eyes with DR showed significant changes in FAZ area, but the sizes of the FAZ area were larger in both the superficial and deep layers in patients with clinical albuminuria than in those with no microalbuminuria (P = 0.007 and P = 0.002, respectively).

Conclusion

These results demonstrate that OCTA provides highly detailed information on retinal microvasculature and that it is a reliable modality to assess DR progression in patients with nephropathy. They also show that renal impairment as a systemic risk factor was associated with enlarged FAZ area in DM.

A Significant Association Between Rhein and Diabetic Nephropathy in Animals: A Systematic Review and Meta-Analysis

Background: Rhein is considered to have beneficial influence on diabetic nephropathy. Animal experiments suggested that the mechanisms of rhein against diabetic nephropathy may involve many processes, but the credibility of the evidence is unclear. Therefore, we conducted systematic review and meta-analysis of pre-clinical animal data to assess the current evidence for rhein effects and mechanisms in treating diabetic nephropathy.

Methods: The databases of PubMed, EMBASE, Web of Science, China National Knowledge Infrastructure, VIP information database, Wanfang Data Information Site, and Chinese Biomedical Literature were searched for this review. SYRCLE’s risk of bias tool for animal studies was applied to assess the methodological quality of studies. A meta-analysis was performed according to the Cochrane Handbook for Systematic Reviews of Interventions by using RevMan 5.3 and STATA/SE 12.0 software. This study was registered with PROSPERO, number CRD42018105220.

Results: Twenty-five studies involving 537 animals were included. There was significant association of rhein with levels of blood glucose (P < 0.05), serum creatinine (Scr) (P < 0.05), urine protein (P < 0.05), kidney tubules injury index (P < 0.05), relative area of kidney collagen (P < 0.05), transforming growth factor-β₁ (P < 0.05), malondialdehyde (P < 0.05), and superoxide dismutase (P < 0.05) compared with that in the control group. No significant association between rhein and endothelin (P > 0.05) was found. Subgroup analysis showed that the hypoglycemic effect of rhein on type 2 diabetic nephropathy was better than on type 1 diabetic nephropathy (P < 0.05).

Conclusions: These findings suggested that rhein has beneficial effects on animal models of diabetic nephropathy, and that the mechanisms are mostly involved with ameliorating levels of TGF-β₁, renal fibrosis, metabolism, and oxidative stress status. However, some factors such as possible publication bias, methodological quality, and sample size may affect the accuracy of positive findings. These limitations suggested that a cautious interpretation of the positive results of this systematic review and meta-analysis is necessary. Therefore, high methodological quality and well-reported animal experiments are needed in future research.

Diabetic Nephropathy in Type 2 Diabetic Retinopathy Requiring Panretinal Photocoagulation

PURPOSE

To investigate the risk factors of diabetic nephropathy in patients with diabetic retinopathy requiring panretinal photocoagulation (PRP) and the visual prognosis.

METHODS

A retrospective review of electronic medical records was conducted at Seoul St. Mary's Hospital, comprising 103 patients with type 2 diabetes mellitus and diabetic retinopathy who underwent PRP from 1996 to 2005. Patients with type 1 diabetes mellitus, non-diabetic renal disease, non-diabetic retinal disease, visually significant ocular disease, high-risk proliferative diabetic retinopathy, and advanced diabetic retinopathy were excluded. The patients were divided into three groups: no nephropathy (group 1, n = 45), microalbuminuria (group 2, n = 16), and advanced nephropathy (group 3, n = 42). Duration of diagnosis of retinopathy and nephropathy, glycosylated hemoglobin, visual acuity, complications, and treatment history were investigated.

RESULTS

The mean glycosylated hemoglobin of group 3 (8.4 ± 1.2) was higher than that of group 1 (7.7 ± 1.0) or group 2 (7.7 ± 1.0) (p = 0.04). Mean interval from PRP to diagnosis of nephropathy was 8.8 ± 6.0 years in group 2 and 8.7 ± 4.9 years in group 3. The significant decrease in visual acuity in group 3 (28 eyes, 35.9%) was significantly higher than that in group 1 (15 eyes, 18.1%, p = 0.01) or group 2 (6 eyes, 20.7%, p = 0.03). Only vitreous hemorrhage showed a significantly higher incidence in groups 2 and 3 than in group 1 (p = 0.02). Multivariate regression analysis revealed that female sex and lower glycosylated hemoglobin were significantly associated with a protective effect on development of nephropathy.

CONCLUSIONS

In the clinical setting, many patients with PRP-requiring diabetic retinopathy develop nephropathy an average of 8 to 9 years after PRP. Male sex and higher glycosylated hemoglobin could be risk factors of nephropathy.

The study of association of Vitamin B12 deficiency in type 2 diabetes mellitus with and without diabetic nephropathy in North Indian Population

AIM

Diabetic Mellitus is the chronic metabolic disorder associated with various complications of heart, eyes, nerves, kidney etc. Diabetic Nephropathy is one of the leading causes of death in diabetic patient. We hypothesized that decrease Vitamin B₁₂ levels is associated with Diabetic Nephropathy. Aim of our study is to study the serum Vitamin B₁₂ levels in type 2 diabetes mellitus patients with and without nephropathy.

METHODS

Our study population consist of 100 subjects out of which 50 cases of Diabetes Mellitus without Diabetic Nephropathy and 50 cases of Diabetes Mellitus with Diabetic Nephropathy. We measured various routine lab parameters, apart from it, we measured spot urinary albumin to creatinine ratio to assess diabetic nephropathy and in special investigation we measured serum Vitamin B₁₂ by chemiluminesence based immunoassay.

RESULT

Serum Vitamin B₁₂ level in the group with nephropathy (181.6±17.6pg/dl) was significantly lower than in the group without nephropathy (286±30.1pg/dl) (p=0.03).

CONCLUSION

Our study points towards the decrease levels of serum Vitamin B₁₂ levels associated with the complication of diabetic mellitus such as diabetic nephropathy. So treatment of Vitamin B₁₂ deficiency by supplementing could prevent the development and progression of diabetic nephropathy and improves the overall management of diabetic patient.

The Role of Oxidative Stress in Diabetic Neuropathy: Generation of Free Radical Species in the Glycation Reaction and Gene Polymorphisms Encoding Antioxidant Enzymes to Genetic Susceptibility to Diabetic Neuropathy in Population of Type I Diabetic Patients

Diabetic neuropathy (DN) represents the main cause of morbidity and mortality among diabetic patients. Clinical data support the conclusion that the severity of DN is related to the frequency and duration of hyperglycemic periods. The presented experimental and clinical evidences propose that changes in cellular function resulting in oxidative stress act as a leading factor in the development and progression of DN. Hyperglycemia- and dyslipidemia-driven oxidative stress is a major contributor, enhanced by advanced glycation end product (AGE) formation and polyol pathway activation. There are several polymorphous pathways that lead to oxidative stress in the peripheral nervous system in chronic hyperglycemia. This article demonstrates the origin of oxidative stress derived from glycation reactions and genetic variations within the antioxidant genes which could be implicated in the pathogenesis of DN. In the diabetic state, unchecked superoxide accumulation and resultant increases in polyol pathway activity, AGEs accumulation, protein kinase C activity, and hexosamine flux trigger a feed-forward system of progressive cellular dysfunction. In nerve, this confluence of metabolic and vascular disturbances leads to impaired neural function and loss of neurotrophic support, and over the long term, can mediate apoptosis of neurons and Schwann cells, the glial cells of the peripheral nervous system. In this article, we consider AGE-mediated reactive oxygen species (ROS) generation as a pathogenesis factor in the development of DN. It is likely that oxidative modification of proteins and other biomolecules might be the consequence of local generation of superoxide on the interaction of the residues of L-lysine (and probably other amino acids) with α-ketoaldehydes. This phenomenon of non-enzymatic superoxide generation might be an element of autocatalytic intensification of pathophysiological action of carbonyl stress. Glyoxal and methylglyoxal formed during metabolic pathway are detoxified by the glyoxalase system with reduced glutathione as co-factor. The concentration of reduced glutathione may be decreased by oxidative stress and by decreased in situ glutathione reductase activity in diabetes mellitus. Genetic variations within the antioxidant genes therefore could be implicated in the pathogenesis of DN. In this work, the supporting data about the association between the -262T > C polymorphism of the catalase (CAT) gene and DN were shown. The -262TT genotype of the CAT gene was significantly associated with higher erythrocyte catalase activity in blood of DN patients compared to the -262CC genotype (17.8 ± 2.7 × 10(4) IU/g Hb vs. 13.5 ± 3.2 × 10(4) IU/g Hb, P = 0.0022). The role of these factors in the development of diabetic complications and the prospective prevention of DN by supplementation in formulations of transglycating imidazole-containing peptide-based antioxidants (non-hydrolyzed carnosine, carcinine, n-acetylcarcinine) scavenging ROS in the glycation reaction, modifying the activity of enzymic and non-enzymic antioxidant defenses that participate in metabolic processes with ability of controlling at transcriptional levels the differential expression of several genes encoding antioxidant enzymes inherent to DN in Type I Diabetic patients, now deserve investigation.

Association of hearing impairment with insulin resistance, β-cell dysfunction and impaired fasting glucose before onset of diabetes

AIM

Diabetes is a known risk factor for hearing impairment. No study regarding the association of insulin resistance (IR), β-cell dysfunction and impaired fasting glucose (IFG) with hearing impairment has been reported in the population without diabetes. We examined these associations using a representative sample of the Korean population.

METHODS

Participants included 1589 males and 2496 females, who were ≥ 20 years of age and without diabetes from the Korea National Health and Nutritional Examination Surveys of the Korean population (2010). Audiometric tests and laboratory examinations were performed. Homeostasis model assessments of IR and β-cell function (HOMA-IR and HOMA-β) were calculated.

RESULTS

The prevalence of both high- and low-/mid-frequency hearing impairment among subjects with IFG was higher compared with those with normal glycaemia (42.2% vs. 24.5%, 14.7% vs. 7.8%, respectively). After adjustment for age, HOMA-IR and HOMA-β showed significant association with high-frequency hearing impairment in males. In the multiple logistic regression analyses adjusting for confounding variables, the presence of IFG, higher HOMA-IR and lower HOMA-β remained as independent risk factors for high-frequency mild hearing impairment in males < 70 years [odds ratio (OR) 1.441, 95% confidence interval (95% CI), 1.056 to 1.967; OR, 1.448, 95% CI, 1.039 to 2.101; and OR, 0.447, 95% CI, 0.274 to 0.729, P < 0.05, respectively).

CONCLUSIONS

IR, β-cell dysfunction and IFG are associated with high-frequency mild hearing impairment in the male population < 70 years before the onset of diabetes.

Novel Genetic Loci Associated With Retinal Microvascular Diameter

BACKGROUND

There is increasing evidence that retinal microvascular diameters are associated with cardiovascular and cerebrovascular conditions. The shared genetic effects of these associations are currently unknown. The aim of this study was to increase our understanding of the genetic factors that mediate retinal vessel size.

METHODS AND RESULTS

This study extends previous genome-wide association study results using 24 000+ multiethnic participants from 7 discovery cohorts and 5000+ subjects of European ancestry from 2 replication cohorts. Using the Illumina HumanExome BeadChip, we investigate the association of single-nucleotide polymorphisms and variants collectively across genes with summary measures of retinal vessel diameters, referred to as the central retinal venule equivalent and the central retinal arteriole equivalent. We report 4 new loci associated with central retinal venule equivalent, one of which is also associated with central retinal arteriole equivalent. The 4 single-nucleotide polymorphisms are rs7926971 in TEAD1 (P=3.1×10(-) (11); minor allele frequency=0.43), rs201259422 in TSPAN10 (P=4.4×10(-9); minor allele frequency=0.27), rs5442 in GNB3 (P=7.0×10(-10); minor allele frequency=0.05), and rs1800407 in OCA2 (P=3.4×10(-8); minor allele frequency=0.05). The latter single-nucleotide polymorphism, rs1800407, was also associated with central retinal arteriole equivalent (P=6.5×10(-12)). Results from the gene-based burden tests were null. In phenotype look-ups, single-nucleotide polymorphism rs201255422 was associated with both systolic (P=0.001) and diastolic blood pressures (P=8.3×10(-04)).

CONCLUSIONS

Our study expands the understanding of genetic factors influencing the size of the retinal microvasculature. These findings may also provide insight into the relationship between retinal and systemic microvascular disease.

Renoprotective effect of lansoprazole in streptozotocin-induced diabetic nephropathy in wistar rats

Proton pump inhibitors (PPIs) have exhibited glucose lowering action in animal models of diabetes; however, their potential in diabetes-related complications has not yet been evaluated. Hence, the present study has been undertaken to investigate the renoprotective potential of lansoprazole in streptozotocin-induced diabetic nephropathy in wistar rats. Diabetic nephropathy was induced with a single injection of streptozotocin (STZ, 45 mg/kg, i.p.). Lansoprazole (40 mg/kg; 80 mg/kg, p.o.; 4 weeks) was administered to diabetic rats after 4 weeks of STZ treatment. A battery of biochemical tests such as serum glucose, glycated hemoglobin, blood urea nitrogen (BUN), serum creatinine, albumin, and kidney weight/body weight (%) ratio were performed to evaluate the renal functions. Oxidative stress was determined by estimating renal thiobarbituric acid reactive species (TBARS) and reduced glutathione (GSH) levels. Lipid profile was assessed by determining serum cholesterol (TC), triglyceride (TG), and high-density lipoprotein (HDL). The STZ-treated rats demonstrated deleterious alterations in kidney functions, enhanced oxidative stress, and disturbed lipid profile. Administration of lansoprazole to diabetic rats significantly reduced serum glucose, glycated hemoglobin, BUN, creatinine, albumin levels, and oxidative stress. Serum lipids like TC and TG were decreased, and HDL was enhanced in lansoprazole-treated STZ rats. The findings of our study indicate that renoprotective effects of lansoprazole may be attributed to its glucose-lowering, lipid-lowering, and antioxidative potential.

Retinal microvascular abnormalities and risk of renal failure in Asian populations

BACKGROUND

Retinal microvascular signs may provide insights into the structure and function of small vessels that are associated with renal disease. We examined the relationship of retinal microvascular signs with both prevalent and incident end-stage renal disease (ESRD) in a multi-ethnic Asian population.

METHODS

A total of 5763 subjects (aged ≥ 40 years) from two prospective population-based studies (the Singapore Malay Eye Study and the Singapore Prospective Study) were included for the current analysis. Retinopathy was graded using the modified Airlie House classification system. Retinal vascular parameters were measured using computer-assisted programs to quantify the retinal vessel widths (arteriolar and venular caliber) and retinal vascular network (fractal dimension). Data on ESRD was obtained by record linkage with the ESRD cases registered by National Registry of Diseases Office, Singapore. Multi-variable adjusted regression analyses were performed to assess the associations of baseline retinal vascular parameters and prevalent and incident ESRD.

RESULTS

At baseline, 21(0.36%) persons had prevalent ESRD. During a median follow-up of 4.3 years, 33 (0.57%) subjects developed ESRD. In our analyses, retinopathy was associated with prevalent ESRD (multi-variable adjusted odds ratio [OR], 3.21, 95% confidence interval [CI]: 1.28-8.05) and incident ESRD (multi-variable adjusted hazard ratio [HR], 2.51, 95%CI: 1.14-5.54). This association was largely seen in person with diabetes (HR, 2.60, 95%CI: 1.01-6.66) and not present in persons without diabetes (HR, 1.65, 95%CI: 0.14-18.98). Retinal arteriolar caliber, retinal venular caliber and retinal vascular fractal dimension were not associated with ESRD.

CONCLUSION

Retinopathy signs in persons with diabetes are related to an increased risk of ESRD; however, other microvascular changes in the retina are not associated with ESRD.

Histopathologic changes in the cochlea associated with diabetes mellitus--a review

BACKGROUND

The pathologic changes that occur as a result of diabetic microangiopathy have been well described for the kidneys and the eyes. Although many studies suggest an association between diabetes mellitus and hearing loss, the pathologic changes in the cochlea in association with the diabetic state remain to be clarified.

AIM/OBJECTIVE

The aim of this review is to determine the effects of diabetes mellitus on cochlear morphology.

METHOD

A comprehensive search for relevant articles was carried out on electronic databases of Ovid Medline, Ovid Medline in Process, PubMed, Ovid Embase,or Biosis Preview, The Cochrane Library, ISI Web of Science, and Scopus. Articles published in English between 1940 and June 2010 were eligible to be reviewed. Using predefined inclusion criteria, published articles on histologic changes occurring in the cochlea due to diabetes mellitus were selected and reviewed, and their findings were synthesized.

RESULTS

Changes were observed in the basement membrane of the capillaries of the stria vascularis and in the basilar membrane, which was remarkably thickened, giving rise to diabetic microangiopathy. Loss of spiral ganglion neurons, organ of Corti cells, and atrophic changes in the stria vascularis were varied and infrequent.

CONCLUSION

There seems to be variable vulnerability of different cochlear cell types to the DM state. Further studies are required to determine the factors responsible for the differences in the histopathologic observations of cochlear tissues.

Expression and effect of TLR4 in rats with diabetic nephropathy

OBJECTIVE

To observe the expression of TLR4 in kidney tissue of rats with diabetic nephropathy and discuss the role of TLR4 in the occurrence and development of the diabetic nephropathy.

METHODS

A total of 60 clean male SD rats were selected and randomly divided into the modeling group and control group after 1 week of breeding, including 30 rats in each group. Biochemical indices as well as the protein expression of TLR4 were observed and compared between two groups at 2 w, 4 w, 6 w, 8 w and 12 w after the modeling, and the correlation between TLR4 and each biochemical indexes was analyzed.

RESULTS

Rats in the modeling group had higher levels of blood glucose, 24-hour urine protein and blood urea nitrogen after the modeling, and showed the increase in the serum creatinine, kidney/body weight ratio, CRP and serum TNF-α at 4w after the modeling, with the significant difference compared to results of the control group (P<0.05). The cross-section area and mean volume of glomerulus in the modeling group at 4 w, 6 w, 8 w and 12 w were significantly higher than those in the control group, with the statistically significant difference (P<0.05). The expression of TLR4 at each time point in the control group was relatively low. Rats in the modeling group had the high expression of TLR4 in kidney's glomerular basement membrane, proximal convoluted tubule and renal interstitial area since 2 w, with the significant difference compared to the control group (P<0.05). The expression in rats of the modeling group was higher than the one of the control group since the 2nd week. As the time flied, its expression increased, with the statistically significant difference between two groups (P<0.05). There was certain correlation between the protein expression of TLR4 and the increased serum titer of 24-hour urine protein excretion, serum creatinine, CRP and TNF-α.

CONCLUSIONS

TLR4 may activate the immuno-inflammatory reactions to play a role in the occurrence and development of the diabetic nephropathy.

Reactive oxygen species promote localized DNA damage in glaucoma-iris tissues of elderly patients vulnerable to diabetic injury

Glaucoma is typically an insidious-onset disease with serious visual consequences that has been positively linked to diabetes mellitus (DM). Glaucoma is more often present in the elderly. Important prognostic factors of glaucoma may be oxidative stress resulting from the toxic effects of glucose, and diabetes-associated vascular complications. Fifty-five patients and control subjects aged 71.0+/-10.1 yrs were enrolled in this study. Iris-tissue samples from DM type-2 patients, primary open-angle glaucoma-positive and -negative DM patients, and from healthy subjects were examined by use of the alkaline comet assay. We measured the DNA damage as numbers of strand breaks (SBs), oxidized purines as glycosyl-formamido-glycosylase (Fpg)-susceptible sites, and oxidized pyrimidines as endonuclease III (Nth)-susceptible sites. It was found that the level of oxidative damage in iris tissue was statistically higher in DM and glaucoma patients than that in healthy controls (oxidized purines: 38.0% and 34.7% vs 15.4%; oxidized pyrimidines: 43.3% and 39.0% vs 23.3%; P<0.001). Interestingly, we found strongly elevated levels of oxidized purines and pyrimidines in glaucomatous patients who also had DM, in comparison with healthy controls (oxidized purines: 55.7% vs 15.4%; oxidized pyrimidines: 61.8% vs 23.3%; P<0.001). Our observations suggest that the generation of reactive oxygen species may promote localized DNA damage in glaucoma-iris tissues of elderly patients vulnerable to diabetic injury.

Microvascular complications of diabetes mellitus: renal protection accompanies cardiovascular protection

The microvascular complications of diabetes mellitus confer substantial morbidity and impair patient quality of life. Dyslipidemia and prolonged hyperglycemia promote an increase in oxidative stress, inflammation, and vascular damage, which together promote endothelial dysfunction and are associated with macrovascular and microvascular complications. Microalbuminuria is an early marker of diabetic nephropathy and an independent risk factor for cardiovascular disease. Diabetic nephropathy is the most common cause of end-stage renal disease in developed countries, and its prevalence is increasing. Preventing or limiting the progression of diabetic nephropathy, as demonstrated in the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial, may prevent or delay renal complications, as well as convey important cardioprotective benefits in patients with type 2 diabetes.

Increased concentrations of soluble CD40 ligand may help to identify type 1 diabetic adolescents and young adults at risk for developing persistent microalbuminuria

BACKGROUND

Recent studies on the pathogenesis of diabetic complications have demonstrated the important role of a number of aberrantly expressed molecules acting together in the development of early diabetic microvascular complications. Soluble CD40 ligand (sCD40L) is supposed to be one of the most likely candidates for both retinopathy and nephropathy.

METHODS

In January 1989, sCD40L was measured in 340 normoalbuminuric diabetic adolescents and young adults. Participants were examined at baseline and biannually thereafter. sCD40L was measured every 2 years during a 16-year follow-up period. sCD40L was also measured in parents.

RESULTS

Over 16 years, 32 out of 340 patients developed persistent microalbuminuria; no patient developed overt diabetic nephropathy. The risk of developing microalbuminuria was higher in children with increased sCD40L at the beginning of the study (using 6 ng/mL as the arbitrary cut-off value) (group A) compared with those with normal sCD40L (group B). Sex did not influence predictive value, sensitivity, or specificity. sCD40L was not significantly correlated with duration of diabetes. The percentage of offspring with both parents having sCD40L above the mean values was significantly higher in group A than in group B. The odds ratio (OR) for the occurrence of microalbuminuria after adjustment for confounding variables in patients with elevated baseline sCD40L was 4.2 (95% CI, 2.1-10.7).

CONCLUSIONS

Persistently increased sCD40L levels from the onset of diabetes might help to identify those normotensive and normoalbuminuric young patients at increased risk of developing incipient nephropathy later in life.

Lipid-lowering therapy in patients with type 2 diabetes: the case for early intervention

Chronic complications of type 2 diabetes, in particular, macrovascular complications, confer substantial morbidity and mortality and adversely affect a patient's quality of life. Early intensive intervention to control cardiovascular risk factors is essential in clinical management. Atherogenic dyslipidaemia characterized by elevated triglycerides, a low level of high-density lipoprotein cholesterol (HDL-C), and an increase in the preponderance of small, dense low-density lipoprotein (LDL) particles, is a key modifiable risk factor for macrovascular diabetic complications. Lowering low-density lipoprotein cholesterol (LDL-C) with a statin (or the combination of statin and ezetimibe) is the main focus for reducing cardiovascular risk in patients with diabetes. However, statins fail to address the residual cardiovascular risk associated with low HDL-C. Fibrates are effective against all components of the atherogenic dyslipidaemia associated with type 2 diabetes. Secondary analyses of the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study suggest a role for early treatment with fenofibrate in improving cardiovascular risk reduction in type 2 diabetes and provide safety data supporting the use of fenofibrate in combination with a statin. Data from the FIELD study suggest that fenofibrate may also have potential to impact on microvascular diabetic complications associated with type 2 diabetes. Data are awaited from the ongoing Action to Control Cardiovascular Risk in Diabetes (ACCORD) study to evaluate the outcome benefits of combining fenofibrate with a statin in patients with type 2 diabetes. Finally, in view of divergent study results and outstanding data, assessment of the risk of the individual with type 2 diabetes is mandatory to assist clinical decision-making when initiating lipid therapy.

Prevalence of nondiabetic renal disease in diabetic patients

BACKGROUND

Diabetic nephropathy is the leading cause of end-stage renal disease in the USA, yet most patients with type 2 diabetes mellitus are not formally evaluated with a renal biopsy. Our aim was to evaluate the prevalence of nondiabetic renal disease (NDRD) in patients with type 2 diabetes mellitus to determine common clinical indicators suggestive of NDRD.

METHODS

A retrospective analysis was performed on biopsy reports of patients who had undergone native renal biopsy between January 1, 1995, and December 31, 2005.

RESULTS

After exclusion of 57 patients, 233 patients with DM2 were included in our analysis. Mean age at the time of biopsy was 58.1 +/- 13.7 years, and 53.0% of the study population were male. There were 124 cases (53.2%) with a pathologic diagnosis of NDRD, 64 (27.5%) with pure diabetic glomerulosclerosis (DGS) and 45 (19.3%) with concurrent NDRD and DGS (CD). Patients with NDRD tended to be younger than those with DGS and had significantly less associated diabetic retinopathy. Focal segmental glomerulosclerosis was the most common lesion found in patients with NDRD and accounted for 21.0% of all NDRD, followed by minimal-change disease (15.3%). IgA nephropathy (15.6%) and membranous glomerulonephritis (13.3%) were the most prevalent lesions found in patients with CD.

CONCLUSIONS

The high prevalence of NDRD found in our population underscores the need for clinicians to consider renal biopsy in diabetic patients with an atypical clinical course, since additional disease-specific therapies may be helpful for this subset of the population.

Statins Ameliorate Glomerular Permeability Changes in Streptozotocin-Induced Diabetic Rats

AIMS

Statins reduce albumin excretion rate and retard the progression of diabetic nephropathy. Whether statins alter size selectivity of glomerular filtration in diabetic rats is not known.

METHODS

The creatinine clearance and the permeability of glomeruli to a group of fluorescein isothiocyanate dextrans of varying molecular weights were studied in rats with streptozotocin-induced diabetes that were treated with either 10 mg/kg rosuvastatin or simvastatin for 5 weeks.

RESULTS

Statin therapy did not significantly alter the increased creatinine clearance in diabetic rats. During the 5 hours of urine collection there was near-complete filtration of 4-, 10-, and 20-kD dextrans in all rat groups studied. The filtration of 70- and 40-kD dextrans was significantly increased in diabetic rats after 5 weeks of diabetes. Rosuvastatin but not simvastatin was associated with partial normalization of glomerular filtration of the 70- and 40-kD dextrans. Treatment with mevalonate (150 mg/kg in drinking water for 5 weeks) reversed the favorable effects of rosuvastatin on glomerular permeability.

CONCLUSIONS

Statin treatment of rats with streptozotocin-induced diabetes ameliorates glomerular permeability changes. The favorable effect of rosuvastatin is probably related to the inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, because mevalonate treatment reversed the favorable effects of rosuvastatin.

Influences on screening for chronic diabetes complications in type 1 diabetes

Screening for the long-term complications of diabetes is a critical component of diabetes management; however, evidence demonstrates that screening rates in diabetes populations are suboptimal. Our objective was to determine the use and predictors of optimal screening behavior, defined as receiving a fasting lipid test, dilated eye exam, spot urine test, foot examination, blood pressure reading, and hemoglobin A1c (HbA1c) in the previous year in a representative cohort of subjects with type 1 diabetes. Data are from the Pittsburgh Epidemiology of Diabetes Complications Study, a prospective cohort study of subjects with childhood onset type 1 diabetes. Data from 325 participants who responded to a survey during 1999-2001 were included in analyses. Reported screening rates were as follows: 87.9% had at least one HbA1c measurement in the past year, 63% had a foot exam, 73.3% had a spot urine test, 81.9% had a dilated eye exam, 93.5% had a blood pressure reading and 68.7% received a fasting lipid profile. Within this group, 37.7% of subjects reported undergoing all five tests (optimal screening). Independent correlates of optimal screening were receiving care from a specialist provider (odds ratio [OR] = 2.4; 95% confidence interval [CI]: 1.4-4.1) and blood glucose monitoring at least weekly (OR = 2.6; 95% CI: 1.1-6.2). These findings indicate that a large proportion of persons with type 1 diabetes are not being screened at the optimal level. Our data indicate that efforts to rectify this should focus on men and those who do not monitor blood glucose, and should involve primary care practitioners.

Cell culture modeling to test therapies against hyperglycemia-mediated oxidative stress and injury

The concept that oxidative stress is a key mediator of nerve injury in diabetes has led us to design therapies that target oxidative stress mechanisms. Using an in vitro model of glucose-treated dorsal root ganglion (DRG) neurons in culture, we can examine both free radical generation, using fluorimetric probes for reactive oxygen species, and cell death via the TUNEL assay. The cell culture system is scaled down to a 96-well plate format, and so is well suited to high-throughput screening. In the present study, we test the ability of three drugs, nicotinamide, allopurinol, and alpha-lipoic acid, alone and in combination to prevent DRG neuron oxidative stress and cell death. This combination of drugs is currently in clinical trial in type 1 diabetic patients. We demonstrate independent effects on oxidative stress and neuronal survival for the three drugs, and neuronal protection using the three drugs in combination. The data strengthen the rationale for the current clinical trial. In addition, we describe an effective tool for rapid preclinical testing of novel therapies against diabetic neuropathy.

Statins ameliorate endothelial barrier permeability changes in the cerebral tissue of streptozotocin-induced diabetic rats

Statins may have favorable effects on endothelial barrier function. The effect of rosuvastatin and simvastatin therapy (10 mg/kg) for 5 weeks on blood-brain barrier (BBB), blood-retinal barrier (BRB), and cardiac muscle permeability of streptozotocin-induced diabetic rats was studied. The size-selective permeability of different vascular beds to a group of fluorescein isothiocyanate dextrans of varying molecular weights was measured. The volume of distribution of 250-, 70-, and 40-kDa dextrans in the cerebral tissue of diabetic rats were significantly increased. The volume of distribution of these dextrans in cerebral tissue was normalized by both statins. Diabetes did not significantly alter the BRB, but both statins decreased the volume of distribution of 70- and 40-kDa dextrans in the retina. The volume of distribution of 40 kDa in cardiac muscle was increased in diabetes, and this change was prevented with statin treatment. Treatment with rosuvastatin and mevalonate (150 mg/kg in drinking water for 5 weeks) did not alter the volume of distribution measurements. We concluded that 1) diabetes in rats is associated with significant changes in the BBB permeability; 2) statin treatment improves the endothelial barrier function in cerebral tissue, retina, and cardiac muscle; and 3) this statin effect could not be attributed to HMGCoA reductase inhibition.

The prevention of diabetic microvascular complications of diabetes: is there a role for lipid lowering?

The role of hyperglycemia in the development of microvascular complications of diabetes, such as nephropathy, retinopathy and neuropathy, has been well documented. Evidence is accumulating to support the concept that dyslipidemia can also contribute to the development of these complications. Lipid-lowering agents, such as statins, have been shown to prevent cardiovascular events in patients with diabetes. However, in addition to preventing macrovascular diseases, statins may also be able to retard the progression of microvascular complications of diabetes. Indeed, in addition to reducing lipid levels, these agents can improve endothelial function and reduce oxidative stress, which can improve microvascular function. These findings would provide further support for the use of lipid-lowering agents in patients with diabetes.

Reactive carbonyls and polyunsaturated fatty acids produce a hydroxyl radical-like species: a potential pathway for oxidative damage of retinal proteins in diabetes

The pattern of oxidized amino acids in aortic proteins of nonhuman primates suggests that a species resembling hydroxyl radical damages proteins when blood glucose levels are high. However, recent studies argue strongly against a generalized increase in diabetic oxidative stress, which might instead be confined to the vascular wall. Here, we describe a pathway for glucose-stimulated protein oxidation and provide evidence of its complicity in diabetic microvascular disease. Low density lipoprotein incubated with pathophysiological concentrations of glucose became selectively enriched in ortho-tyrosine and meta-tyrosine, implicating a hydroxyl radical-like species in protein damage. Model system studies demonstrated that the reaction pathway requires both a reactive carbonyl group and a polyunsaturated fatty acid, involves lipid peroxidation, and is blocked by the carbonyl scavenger aminoguanidine. To explore the physiological relevance of the pathway, we used mass spectrometry and high pressure liquid chromatography to quantify oxidation products in control and hyperglycemic rats. Hyperglycemia raised levels of ortho-tyrosine, meta-tyrosine, and oxygenated lipids in the retina, a tissue rich in polyunsaturated fatty acids. Rats that received aminoguanidine did not show this increase in protein and lipid oxidation. In contrast, rats with diet-induced hyperlipidemia in the absence of hyperglycemia failed to exhibit increased protein and lipid oxidation products in the retina. Our observations suggest that generation of a hydroxyl radical-like species by a carbonyl/polyunsaturated fatty acid pathway might promote localized oxidative stress in tissues vulnerable to diabetic damage. This raises the possibility that antioxidant therapies that specifically inhibit the pathway might delay the vascular complications of diabetes.

Hypertensive retinopathy: there's more than meets the eye

Hypertension is associated with increased cardiovascular risk, leading to systemic end-organ damage, including retinopathy. However, the recent European Society of Hypertension-European Society of Cardiology and World Health Organization-International Society of Hypertension 2003 guidelines propose new prognostic indications for the classification of hypertensive retinopathy. In particular, grades I and II are no longer included among signs of end-organ damage, and only grades III and IV are retained as associated clinical conditions for the stratification of global cardiovascular risk. This review article will focus on the wider implications of clinical markers of microvascular damage in the retina, with specific reference to hypertension and end-organ damage. Early recognition of retinal changes remains an important step in the risk stratification of hypertensive patients.

Associations of mortality and diabetes complications in patients with type 1 and type 2 diabetes: early treatment diabetic retinopathy study report no. 27

OBJECTIVE

Diabetes is a leading cause of morbidity and mortality. The purpose of this study is to assess the associations between diabetes complications and mortality in the Early Treatment Diabetic Retinopathy Study (ETDRS).

RESEARCH DESIGN AND METHODS

We examined demographic, clinical, and laboratory characteristics of the 3,711 subjects enrolled in the ETDRS, a randomized controlled clinical trial designed to evaluate the role of laser photocoagulation and aspirin therapy for diabetic retinopathy. The outcome assessed was all-cause mortality. Multivariable Cox proportional hazards regression was used to assess associations between diabetes complications and mortality for type 1 and type 2 diabetes separately.

RESULTS

The 5-year estimates of all-cause mortality were 5.5 and 18.9% for patients with type 1 and type 2 diabetes, respectively. In patients with type 1 diabetes, amputation (hazard ratio [HR] 5.08 [95% CI 2.06-12.54]) and poor visual acuity (1.74 [1.10-2.75]) remained significantly associated with mortality, after adjusting for other diabetes complications and baseline characteristics. In patients with type 2 diabetes, macrovascular disease and worsening levels of nephropathy, neuropathy, retinopathy, and visual acuity are associated with progressively increasing risks of mortality, after controlling for other baseline risk factors.

CONCLUSIONS

Amputation is the strongest predictor for mortality in patients with type 1 diabetes. All complications independently predict mortality in patients with type 2 diabetes. There is an increased risk for mortality as the degree of each complication worsens. Additional studies are needed to investigate the effectiveness of tertiary prevention to decrease mortality in these patients.

Risk factors for renal replacement therapy in the Early Treatment Diabetic Retinopathy Study (ETDRS), Early Treatment Diabetic Retinopathy Study Report No. 26

BACKGROUND

Diabetes is a leading cause of end-stage renal disease (ESRD). The purpose of this study is to assess the risk factors for renal replacement therapy (RRT) in the Early Treatment Diabetic Retinopathy Study (ETDRS).

METHODS

We examined demographic, clinical, and laboratory characteristics of the 2226 subjects with complete laboratory data enrolled in the ETDRS. The primary renal variable evaluated was the time to development of renal replacement therapy, defined as the need for dialysis or transplantation. Multivariable Cox proportional hazards regression was used to assess risk factors for type 1 and type 2 diabetes separately.

RESULTS

The 5-year estimated incidence of RRT in the entire ETDRS population was 10.2% and 9.8% for patients with type 1 and type 2 diabetes, respectively. Of those patients with complete data, 127 of 934 (14%) of patients with type 1 diabetes, and 150 of 1292 (12%) patients with type 2 diabetes required RRT during the study. Baseline risk factors common to type 1 and type 2 diabetes included elevated total cholesterol, and serum creatinine; and low serum albumin and anemia. Other risk factors significant in type 1 diabetes included body mass index (BMI), shorter duration of diabetes, elevated hemoglobin A(1c) (HbA(1c)), elevated systolic blood pressure, and the development of proliferative diabetic retinopathy. Risk factors significant in type 2 diabetes, but not type 1 diabetes, included younger age, proteinuria, and elevated triglycerides.

CONCLUSION

In this study, major modifiable risk factors such as hypertension, dyslipidemia, and hyperglycemia were found to be predictive of RRT. Other predictors were markers of vascular pathology and inflammation, proteinuria, hypoalbuminemia, and increased serum creatinine. Controlled clinical trials with treatment strategies that improve serum lipid levels, systemic blood pressure, glycemic control, and markers of inflammation may be important in furthering our knowledge on the pathogenesis of diabetic complications such as nephropathy and ESRD.

Diabetic nephropathy and retinopathy

Diabetic nephropathy and retinopathy are arguably the two most dreaded complications of diabetes. Together they contribute to serious morbidity and mortality. As they progress to end-stage renal disease and blindness, they impose enormous medical, economic,and social costs on both the patient and the health care system. Because nephropathy and retinopathy are frequently linked in patients,this article reviews their common and individual aspects of pathophysiology, clinical features, and management.

Probabilistic approach to developing nephropathy in diabetic patients with retinopathy

It is well known that diabetes is a risk factor for many complications including diabetic retinopathy and nephropathy. An interesting question is whether a diabetic patient who has developed a retinopathy develops a nephropathy sooner. We approached this problem by calculating the conditional probability that a diabetic patient will develop a second complication, given that they had already developed the first complication. We also propose the application of Bayes' formula to estimate the probability of developing the second complication, given that the first complication had developed previously. We compared these two methods by applying them to analyse 5473 patients with type 2 diabetes. The results of our experience are described.

Retinal vessel diameters and the incidence of gross proteinuria and renal insufficiency in people with type 1 diabetes

Early retinal vessel caliber changes may predict risk of diabetic nephropathy. We examined the association of retinal vessel diameters and the incidence of gross proteinuria and renal insufficiency in a population-based cohort of people with type 1 diabetes (n = 557). Baseline retinal photographs were digitized, and diameters of individual retinal vessels were measured and summarized. Incident cases of gross proteinuria and renal insufficiency were identified over a 16-year period. Larger retinal venular diameter was associated with higher cumulative incidence of gross proteinuria (18.6, 25.4, 37.7, and 50.4%, comparing increasing venular diameter quartiles) and renal insufficiency (10.7, 15.5, 23.2, and 32.8%). After adjusting for age, sex, duration of diabetes, HbA(1c) levels, baseline retinopathy levels, and other factors, larger retinal venular diameter was associated with an increased risk of gross proteinuria (RR 1.53, 95% CI 1.19-1.97, comparing 4th vs. 1st to 3rd quartiles of venular diameter) and renal insufficiency (1.51, 1.05-2.17). Retinal arteriolar diameter was not associated with either gross proteinuria or renal insufficiency. We conclude that in individuals with type 1 diabetes, larger retinal venular diameter is independently associated with the long-term incidence of gross proteinuria and renal insufficiency and may provide additional predictive information regarding risk of nephropathy.

Biochemical Pathways for Microvascular Complications of Diabetes Mellitus

OBJECTIVE

To review the current biochemical theories on how diabetes contributes to microvascular disease.

DATA SOURCES

MEDLINE search (1980-June 2003) and bibliographies of articles obtained on this topic.

STUDY SELECTION AND DATA EXTRACTION

Articles identified from the data sources were evaluated and those deemed relevant to this review were incorporated.

DATA SYNTHESIS

The prevailing biochemical theories on how diabetes leads to microvascular disease include increased polyol (sorbitol/aldose reductase) pathway flux, production of advanced glycation end-products, generation of reactive oxygen species, and activation of diacylglycerol and protein kinase C isoforms. These pathways contribute to endothelial damage and dysfunction and may alter gene functioning.

CONCLUSIONS

Each pathway, via varied and often overlapping mechanisms, contributes to altered microvascular function that leads to the development of retinopathy, neuropathy, and nephropathy, the major microvascular complications associated with diabetes.

Diabetic nephropathy

As the epidemic of diabetes spreads so does the number of patients at risk for developing diabetic nephropathy, which occurs in 20% to 40% of all diabetic patients. Indeed, diabetes is the most common cause of end-stage renal disease (ESRD) in the United States, accounting for > 40% of patients starting renal replacement therapy each year. Unfortunately, the outcome for diabetic patients with ESRD is worse than that for nondiabetic patients because of comorbid conditions in the diabetic population. However, with early and intensive blood glucose and blood pressure control--including the use of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers--the development and progression of diabetic kidney disease can be slowed.

Prevention and treatment of diabetic nephropathy in older patients

Renal disease in older diabetic patients is costly in terms of morbidity, mortality and expenditure. Therefore, prevention and treatment of diabetic nephropathy has become a prominent goal in the treatment of patients with diabetes mellitus. Preventive treatment should begin no later than at the stage of microalbuminuria, and regular screening for microalbuminuria is recommended for all patients with diabetes, irrespective of age. Improved metabolic control has been demonstrated to lower urinary albumin excretion. Target glycosylated haemoglobin levels should be below 7%, or 1% above the upper limit of normal of non-diabetic subjects. The use of an intensified treatment regimen is recommended. Insulin therapy has no adverse effects on renal indexes. To preserve renal function in older diabetic patients, blood pressure should be kept at or below 130/80 mm Hg. Treatment with ACE inhibitors or angiotensin II receptor antagonists (angiotensin II receptor blockers; ARBs) is superior to other pharmacological therapy, and should be initiated as first-line treatment. Most of the calcium channel antagonists have been found to increase or to have no effect on microalbuminuria despite blood pressure reduction. Moreover, there is substantial controversy as to whether they may be associated with increased cardiovascular morbidity. Non-dihydropyridine derivatives and calcium channel antagonists, such as nitrendipine, may be nephroprotective and have favourable effects on patients outcomes. A renoprotective action of diuretics may be confined to indapamide. Although beta-adrenoreceptor blockers are effective antihypertensive agents, they may not adequately preserve kidney function in older diabetic patients. However, as add-on treatment to ACE inhibitors or ARBs, they are particularly beneficial in nephropathic patients at risk of cardiovascular disease or with arrhythmias, in whom they may prove life-saving.

Vascular complications and gene therapy

For gene therapy, the last few years have been an exciting period. Encouraging results from several successful gene therapy trials were reported. Children born with a life-threatening immune system disorder, severe combined immune deficiency (SCID), were cured after receiving gene therapy for replacement of their defective adenosine deaminase (ADA) gene. Gene therapy successes related to vascular complications were also reported. The first human gene therapy trial for a blood-vessel disorder was performed successfully, in which copies of an angiogenic gene, the vascular endothelial growth factor (VEGF) gene, were directly delivered to the area surrounding the diseased artery of the leg of a patient with peripheral artery disease. Within a few days, this stimulated the growth of new blood vessels around the blockage in the ailing blood vessel and helped avoid amputation. In 1998, a patient with genetically small arteries became the first to receive VEGF gene therapy in the heart. Multiple copies of a plasmid with the VEGF gene were delivered into the damaged area of the heart, and a few days later angiogenesis ensued that helped bypass the blocked vessel, with markedly reduced chest pain in the patient. Gene therapy is becoming a reality and, more importantly, it appears to be safe and does not require supplementary immuno-suppressing drugs. Gene therapy seems to have begun delivering on its promises.