The changing natural history of nephropathy in type I diabetes

Sex differences in the development of kidney disease in individuals with type 1 diabetes mellitus: a contemporary analysis

BACKGROUND

Kidney disease in patients with type 1 diabetes historically has been believed to be more prevalent in men. Because recent data do not reflect this pattern, we evaluated whether a sex difference persists.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

We used 18-year follow-up data from the Pittsburgh Epidemiology of Diabetes Complications Study (n = 788; baseline mean age, 27 years; diabetes duration, 19 years).

PREDICTOR OR FACTOR

Sex and diagnosis interval (1950-1964 or 1965-1980).

OUTCOMES

Cumulative incidences of macroalbuminuria (albumin excretion rate >200 μg/min) and end-stage renal disease (ESRD; kidney failure, dialysis, or transplant) were evaluated at 20, 25, and 30 years of diabetes duration. To address potential survival bias, death certificate information was included in determining ESRD for those who died before baseline (n = 145). Analyses were stratified by diagnosis year (1950-1964 or 1965-1980).

OTHER MEASUREMENTS

Kidney disease risk factor information was available.

RESULTS

A significant interaction was noted between sex and diagnosis cohort for ESRD incidence by 25 (P = 0.002) and 30 (P < 0.001) years' duration. Thus, within the 1950-1964 cohort (210 men and 180 women), ESRD incidence was higher in men compared with women by 25 (30.6% vs 18.0%, respectively) and 30 (43.4% vs 24.6%, respectively) years' duration of type 1 diabetes. However, in the 1965-1980 cohort (260 men and 283 women), the incidence was higher in women (7.6% vs 13.8% by 25 years [P = 0.04] and 13.7% vs 21.0% by 30 years' duration [P = 0.09] in men vs women, respectively). Results were similar for macroalbuminuria.

LIMITATIONS

Study participants were not followed up from the onset of diabetes; thus, risk-factor data from that period are lacking.

CONCLUSIONS

Our data suggest that the male excess of type 1 diabetic kidney disease cases observed in the earlier cohort has been eliminated in the younger cohort. The reason for this dramatic change presently is unclear, but should be addressed in subsequent studies.

Macrovascular angiopathy in children and adolescents with type 1 diabetes

Diabetes represents one of the most common diseases globally. Worryingly, the worldwide incidence of type 1 diabetes (T1D) is rising by 3% per year. Despite the rapid increase in diabetes incidence, recent advances in diabetes treatment have been successful in decreasing morbidity and mortality from diabetes-related retinopathy, nephropathy, and neuropathy. In contrast, there is clear evidence for the lack of improvement in mortality for cardiovascular diseases (CVDs). This emphasizes the importance of focusing childhood diabetes care strategies for the prevention of CVD in adulthood. Furthermore, although most work on diabetes and macrovascular disease relates to type 2 diabetes, it has been shown that the age-adjusted relative risk of CVD in T1D far exceeds that in type 2 diabetes. As T1D appears predominantly during childhood, those with T1D are at greater risk for coronary events early in life and require lifelong medical attention. Because of the important health effects of CVDs in children and adolescents with T1D, patients, family members, and care providers should understand the interaction of T1D and cardiovascular risk. In addition, optimal cardiac care for the patient with diabetes should focus on aggressive management of traditional cardiovascular risk factors to optimize those well-recognized as well as new specific risk factors which are becoming available. Therefore, a complete characterization of the molecular mechanisms involved in the development and progression of macrovascular angiopathy is needed. Furthermore, as vascular abnormalities begin as early as in childhood, potentially modifiable risk factors should be identified at an early stage of vascular disease development.

Need for better diabetes treatment for improved renal outcome

Diabetic nephropathy has become a worldwide epidemic accounting for approximately one-third of all cases of end-stage renal disease. The problem is expected to grow, as the prevalence of diabetes is expected to increase from 285 million patients at present to 438 million patients in the year 2030, with increasing prevalence of diabetes particularly in Asia, and a global prevalence of microalbuminuria of ∼ 40%. This will have a major societal impact because of the enormous financial burden of renal replacement therapy and the invalidating character of this disease. Improved management of diabetes is clearly required, including improved glycemic control to avoid initiation of diabetic nephropathy, particularly in high-risk patients. Recently, the benefits of strict glycemic control on micro- and macrovascular complications have been questioned despite the clear association in observational studies between hyperglycemia and complications. It has been suggested that the benefit of lowering glucose is partly offset by side effects to the glucose-lowering medications, such as hypoglycemia, weight gain, and fluid retention. New treatment strategies with fewer side effects are necessary. Such a treatment could be an incretin-based treatment with glucagon-like peptide 1 analogs, with dipeptidyl peptidase-4 inhibitors that have recently been marketed, or with sodium-glucose transporter 2 inhibitors that are being developed in phase III studies. However, studies with renal end points using these agents are lacking.

Genetic variation in the matrix metalloproteinase genes and diabetic nephropathy in type 1 diabetes

Genetic data support the notion that polymorphisms in members of the matrix metalloproteinase (MMP) family of genes play an important role in extracellular matrix remodeling and contribute to the pathogenesis of vascular disease. To identify novel genetic markers for diabetic nephropathy (DN), we examined the relationship between MMP gene polymorphisms and DN in the Genetics of Kidneys in Diabetes (GoKinD) population. Genotypic data from the Genetic Association Information Network (GAIN) type 1 DN project were analyzed for associations across 21 MMP genes in 1705 individual with type 1 diabetes, including 885 normoalbuminuric control subjects and 820 advanced DN case subjects. In total, we investigated the role of 1283 SNPs (198 genotyped SNPs and 1085 imputed SNPs) mapping to the MMP genes. We identified associations at several correlated SNPs across a 29.2kb interval on chromosome 11q at the MMP-3/MMP-12 locus. The strongest associations occurred at 2 highly-correlated SNPs, rs610950 (OR=0.50, P=1.6×10(-5)) and rs1277718 (OR=0.50, P=2.1×10(-5)). Further examination of this locus identified 17 SNPs (2 genotyped SNPs and 15 imputed SNPs) in complete linkage disequilibrium associated with DN (P-values<2.5×10(-4)), including a non-synonymous SNP (rs652438, Asn357Ser) located in exon 8 of MMP-12 that significantly reduced the risk of DN among carriers of the serine substitution relative to homozygous carriers of asparagine (OR=0.51; 95% CI=0.37-0.71, P=6.2×10(-5)). Taken together, our study suggests that genetic variations within the MMP-3/MMP-12 locus influence susceptibility of DN in type 1 diabetes.

Risk for ESRD in type 1 diabetes remains high despite renoprotection

Historically, patients with type 1 diabetes and macroalbuminuria had high competing risks: cardiovascular death or renal failure. Here, we assessed these risks in patients receiving therapies implemented during the last 30 years. Between 1991 and 2004, we enrolled 423 white patients with type 1 diabetes who developed macroalbuminuria (albumin excretion rate, ≥300 μg/min). With follow-up for 98% through 2008, ESRD developed in 172 patients (incidence rate, 5.8/100 person-years), and 29 died without ESRD (mortality rate, 1/100 person-years). The majority of these outcomes occurred between ages 36 and 52 years with durations of diabetes of 21 to 37 years. The 15-year cumulative risks were 52% for ESRD and 11% for pre-ESRD death. During the 15 years of follow-up, the use of renoprotective treatment increased from 56 to 82%, and BP and lipid levels improved significantly; however, the risks for both ESRD and pre-ESRD death did not change over the years analyzed. There were 70 post-ESRD deaths, and the mortality rate was very similar during the 1990s and the 2000s (11/100 person-years versus 12/100 person-years, respectively). Mortality was low in patients who received a pre-emptive kidney transplant (1/100 person-years), although these patients did not differ from dialyzed patients with regard to predialysis eGFR, sex, age at onset of ESRD, or duration of diabetes. In conclusion, despite the widespread adoption of renoprotective treatment, patients with type 1 diabetes and macroalbuminuria remain at high risk for ESRD, suggesting that more effective therapies are desperately needed.

[Microvascular and macrovascular complications in children and adolescents with type 1 diabetes mellitus]

Diabetes-related microvascular and macrovascular complications, as retinopathy, nephropathy and neuropathy are life-threatening complications in children and adolescents with type 1 diabetes mellitus (T1DM). Risk factors for the development of complications are longer duration of diabetes, older age and puberty. Further risk factors include smoking, hypertension, higher body mass index and dyslipoproteinaemia. Therefore prevention and screening for complications is an important part in the care of children and adolescents with T1DM. Target levels to reduce the risk of microvascular and macrovascular complications in children and adolescents with T1DM are the following: HbA1c<7.5%, lipids in normal range, blood pressure<90th percentile by age, sex and height, BMI<95th percentile, no smoking and physical activity. Screening for retinopathy and microalbuminuria should start from 11 years with two years diabetes duration and from 9 years with 5 years duration and after 2 years diabetes duration in an adolescent. Thereafter screening should be performed annually. Blood pressure should be measured at least annually. Screening for fasting blood lipids should be performed soon after diagnosis in all children with T1DM aged over 12 years. If normal results are obtained, this should be repeated every 5 years.

Adherence challenges in the management of type 1 diabetes in adolescents: prevention and intervention

PURPOSE OF REVIEW

Despite the availability of effective therapies, adolescents with type 1 diabetes demonstrate poorer adherence to treatment regimens compared with other pediatric age groups. Nonadherence is tightly linked to suboptimal glycemic control, increasing morbidity, and risk for premature mortality. This article will review barriers to adherence and discuss interventions that have shown promise in improving outcomes for this population.

RECENT FINDINGS

Adolescents face numerous obstacles to adherence, including developmental behaviors, flux in family dynamics, and perceived social pressures, which compound the relative insulin resistance brought on by pubertal physiology. Some successful interventions have relied on encouraging nonjudgmental family support in the daily tasks of blood glucose monitoring and insulin administration. Other interventions overcome these barriers through the use of motivational interviewing and problem-solving techniques, flexibility in dietary recommendations, and extending provider outreach and support with technology.

SUMMARY

Effective interventions build on teens' internal and external supports (family, technology, and internal motivation) in order to simplify their management of diabetes and provide opportunities for the teens to share the burdens of care. Although such strategies help to minimize the demands placed upon teens with diabetes, suboptimal glycemic control will likely persist for the majority of adolescents until technological breakthroughs allow for automated insulin delivery in closed loop systems.

Risk markers of future microalbuminuria and hypertension based on clinical and morphological parameters in young type 1 diabetes patients

BACKGROUND

Nephropathy is a severe complication of type 1 diabetes and develops in 30% of patients. Currently, it is not possible to identify young patients at risk prior to the development of microalbuminuria (MA) and/or hypertension (HT).

OBJECTIVE

To study predictors of MA and/or HT in young normoalbuminuric (NA) patients with type 1 diabetes.

SUBJECTS AND METHODS

Forty-six NA and normotensive (NT) type 1 diabetes patients, regularly followed since onset with checks on metabolic control, kidney function, and MA, were investigated with kidney biopsies and 24-h ambulatory blood pressure measurements (ABPMs) after 10.6 yr of diabetes. The patients were followed another six and a half years with regard to the development of MA and HT.

RESULTS

Fifteen patients developed MA and/or HT during follow-up. The strongest risk markers were poor metabolic control after puberty, high day-time systolic blood pressure (BP), and increased BMT at 10 yr, which explained 62% of the outcome for MA and/or HT at 17 yr duration with 77% sensitivity and 65% specificity. The threshold values were long-term postpubertal HbA(1c) > 8.2%, day-time systolic BP > 130 mmHg, and BMT > 490 nm/1.73 m(2).

CONCLUSIONS

Normoalbuminuric and NT patients at risk of developing MA and HT could be identified and might benefit from an early start of antihypertensive therapy and improvement of metabolic control.

Cumulative risk, age at onset, and sex-specific differences for developing end-stage renal disease in young patients with type 1 diabetes: a nationwide population-based cohort study

OBJECTIVE

This study aimed to estimate the current cumulative risk of end-stage renal disease (ESRD) due to diabetic nephropathy in a large, nationwide, population-based prospective type 1 diabetes cohort and specifically study the effects of sex and age at onset.

RESEARCH DESIGN AND METHODS

In Sweden, all incident cases of type 1 diabetes aged 0-14 years and 15-34 years are recorded in validated research registers since 1977 and 1983, respectively. These registers were linked to the Swedish Renal Registry, which, since 1991, collects data on patients who receive active uremia treatment. Patients with > or =13 years duration of type 1 diabetes were included (n = 11,681).

RESULTS

During a median time of follow-up of 20 years, 127 patients had developed ESRD due to diabetic nephropathy. The cumulative incidence at 30 years of type 1 diabetes duration was low, with a male predominance (4.1% [95% CI 3.1-5.3] vs. 2.5% [1.7-3.5]). In both male and female subjects, onset of type 1 diabetes before 10 years of age was associated with the lowest risk of developing ESRD. The highest risk of ESRD was found in male subjects diagnosed at age 20-34 years (hazard ratio 3.0 [95% CI 1.5-5.7]). In female subjects with onset at age 20-34 years, the risk was similar to patients' diagnosed before age 10 years.

CONCLUSIONS

The cumulative incidence of ESRD is exceptionally low in young type 1 diabetic patients in Sweden. There is a striking difference in risk for male compared with female patients. The different patterns of risk by age at onset and sex suggest a role for puberty and sex hormones.

Activation of protein kinase C isoforms and its impact on diabetic complications

Both cardio- and microvascular complications adversely affect the life quality of patients with diabetes and have been the leading cause of mortality and morbidity in this population. Cardiovascular pathologies of diabetes have an effect on microvenules, arteries, and myocardium. It is believed that hyperglycemia is one of the most important metabolic factors in the development of both micro- and macrovascular complications in diabetic patients. Several prominent hypotheses exist to explain the adverse effect of hyperglycemia. One of them is the chronic activation by hyperglycemia of protein kinase (PK)C, a family of enzymes that are involved in controlling the function of other proteins. PKC has been associated with vascular alterations such as increases in permeability, contractility, extracellular matrix synthesis, cell growth and apoptosis, angiogenesis, leukocyte adhesion, and cytokine activation and inhibition. These perturbations in vascular cell homeostasis caused by different PKC isoforms (PKC-alpha, -beta1/2, and PKC-delta) are linked to the development of pathologies affecting large vessel (atherosclerosis, cardiomyopathy) and small vessel (retinopathy, nephropathy and neuropathy) complications. Clinical trials using a PKC-beta isoform inhibitor have been conducted, with some positive results for diabetic nonproliferative retinopathy, nephropathy, and endothelial dysfunction. This article reviews present understanding of how PKC isoforms cause vascular dysfunctions and pathologies in diabetes.

Occurrence of microalbuminuria in young people with Type 1 diabetes: importance of age and diabetes duration

AIMS

To determine the occurrence of microalbuminuria in young people with Type 1 diabetes mellitus followed prospectively for 2 years and to relate the presence of persistent elevations in urinary albumin excretion (UAE) to age, diabetes duration, puberty and other factors.

METHODS

During a 2 year period, random urine samples were obtained from 471 patients, aged 8-18 years (mean +/-sd 12.9 +/- 2.3 years) with Type 1 diabetes duration 5.6 +/- 3.0 years, as part of routine clinical care. Urine albumin and creatinine concentrations were measured in 1310 samples (median, 3 samples per patient) and the albumin:creatinine ratio was calculated (in micrograms albumin per milligram creatinine). Height, weight, blood pressure (BP), glycated haemoglobin (HbA(1c)), blood glucose monitoring frequency and Tanner staging were collected from patients' medical records.

RESULTS

Twenty-three per cent of patients had one or more sample with elevated UAE (> or =20 microg/mg) and 9.3% had persistent elevations (> or =2 samples > or =20 microg/mg). Those with and without persistent microalbuminuria did not differ significantly in age, diabetes duration, z-score for body mass index, pubertal status or BP percentile. Ten per cent of children <13 years old and 9% of children > or =13 years old had persistent microalbuminuria. Persistent microalbuminuria was significantly associated with diabetes duration only in older children (duration 0.5-3 years, 4%; 4-6 years, 8%; > or =7 years, 14%; P = 0.02, trend test). Mean HbA(1c) over the 2 years was 8.7 +/- 1.2%. In a logistic regression model, mean HbA(1c) was the only significant predictor of persistent microalbuminuria (odds ratio 1.3, 95% confidence interval 1.0-1.6, P = 0.05).

CONCLUSIONS

Microalbuminuria in older children with Type 1 diabetes is likely to be clinically significant. In younger children, it may reflect functional, reversible renal changes. Longitudinal analysis is needed to confirm the probable transient nature of microalbuminuria in young patients with Type 1 diabetes.

Study of protein profiling of human urine in diabetic hypertensive nephropathy versus normal healthy controls

BACKGROUND

This study describes the levels of protein acting as biomarkers affecting hypertensive diabetic nephropathy in the local Pakistani population.

METHODS

Patients with both hypertensive nephropathy and diabetes type 2 and normal healthy controls were recruited from Sheikh 380 Zayed Hospital, Lahore, Pakistan. Individuals were equally divided into three different groups: group A was the control, group B was hypertensive without diabetic nephropathy, and group C was hypertensive with diabetic nephropathy. Biochemical parameters related to the hypertensive diabetic nephropathy and specific proteins markers were analyzed by two-dimensional liquid chromatography followed by mass spectrometric standard reference protocols. The proteins that showed variation between test and control samples were identified by mass spectrometric analysis.

RESULTS

The biochemical data showed significantly higher values of fasting blood sugar, diastolic and systolic blood pressure, and total serum and urinary proteins in the diabetes groups with hypertension but with or without nephropathy compared to the control group. The levels of proteins that act as biomarkers like albumin were the most significant in urine samples of hypertensive diabetic nephropathy group A compared to groups B and C.

CONCLUSIONS

The prevalence of proteins in hypertensive patients with diabetic nephropathy is higher compared to that in normal patients without nephropathy in the Pakistani population.

Glucose control is associated with patient survival in diabetic patients after renal transplantation

INTRODUCTION

The efficacy of tight glycemic control for the prevention of death and renal failure in the general diabetic population is well established. However, in diabetic renal-allograft recipients, the effect of different treatment strategies on outcomes is undetermined.

METHODS

We conducted a cohort study of 798 diabetic, renal-allograft recipients transplanted at the Medical University of Vienna between 1990 and 2004. We studied the influence of glucose parameters and diabetes treatment on mortality and graft loss. Marginal-structural models and multivariable Cox regression analysis were used to control for confounding.

RESULTS

Maximal glucose levels but not HbA1c were independently associated with mortality. Being in the highest quartile of maximal glucose increased the adjusted risk of death by a factor of 2.2 (P value for trend 0.009). Furthermore, in patients receiving insulin, the risk of death was increased 1.7-fold (95% confidence interval 0.9-3.1) compared with diet and 2.0-fold (95% confidence interval 1.1-3.7) compared with oral medication. Maximal glucose, HbA1c, or diabetes treatment did not influence death-censored functional graft survival.

DISCUSSION

In conclusion, maximal glucose levels and insulin treatment were independently associated with higher rates of mortality in our cohort of diabetic, renal-allograft recipients. However, graft survival was unaffected.

Lipoprotein-associated phospholipase A2, C-reactive protein, and coronary artery disease in individuals with type 1 diabetes and macroalbuminuria

Given the paucity of data in type 1 diabetes concerning lipoprotein-associated phospholipase A( 2) (Lp-PLA(2)), we examined its prospective relationship with coronary artery disease (CAD), as well as the effect of modification by C-reactive protein (CRP) and haptoglobin genotype, in individuals with type 1 diabetes who are at an increased risk for CAD due to also having macroalbuminuria (n=96). Although Lp-PLA(2) activity was univariately predictive of CAD (HR=1.54 per SD, p=0.009), this relationship was not significant after covariate adjustment (p=0.59). There was a significant interaction between Lp-PLA(2) and CRP (p=0.02), i.e. those with both markers greater than the median level were more likely to have a CAD event than those persons with low levels of both (HR=2.89, p=0.06). When stratified by haptoglobin genotype, Lp-PLA(2) was predictive of CAD in persons with the 2/1 (HR=2.40, p=0.05), but not 2/2 (HR=0.66, p=0.27), genotype. The association between Lp-PLA(2) activity and CAD differs by CRP and haptoglobin genotype in this group of persons with type 1 diabetes and macroalbuminuria.

Influence of genetic background on albuminuria and kidney injury in Ins2(+/C96Y) (Akita) mice

Previous studies have shown that Akita mice bearing the Ins2(+/C96Y) mutation have significant advantages as a type I diabetes platform for developing models of diabetic nephropathy (DN; Gurley SB, Clare SE, Snow KP, Hu A, Meyer TW, Coffman TM. Am J Physiol Renal Physiol 290: F214-F222, 2006). In view of the critical role for genetic factors in determining susceptibility to DN in humans, we investigated the role of genetic background on kidney injury in Akita mice. To generate a series of inbred Akita mouse lines, we back-crossed the Ins2(C96Y) mutation more than six generations onto the 129/SvEv and DBA/2 backgrounds and compared the extent of hyperglycemia and renal disease with the standard C57BL/6-Ins2(+/C96Y) line. Male mice from all three Akita strains developed marked and equivalent hyperglycemia. However, there were significant differences in the level of albuminuria among the lines with a hierarchy of DBA/2 > 129/SvEv > C57BL/6. Renal and glomerular hypertrophy was seen in all of the lines, but significant increases in mesangial matrix compared with baseline nondiabetic controls were observed only in the 129 and C57BL/6 backgrounds. In F1(DBA/2 x C57BL/6)-Ins2(+/C96Y) mice, the extent of albuminuria was similar to the parental DBA/2-Ins2(+/C96Y) line; they also developed marked hyperfiltration. These studies identify strong effects of genetic background to modify the renal phenotype associated with the Ins2(C96Y) mutation. Identification of these naturally occurring strain differences should prove useful for nephropathy modeling and may be exploited to allow identification of novel susceptibility alleles for albuminuria in diabetes.

Endothelial nitric oxide synthase gene polymorphisms and diabetic nephropathy: a HuGE review and meta-analysis

Candidate-gene association studies that examined the association between polymorphisms of endothelial nitric oxide synthase (NOS3) gene (G894T, 4b/a, and T786C) and diabetic nephropathy or diabetes leading to severe nephropathy produced inconclusive results. Thus, a meta-analysis of all candidate-gene association studies with endothelial nitric oxide synthase genotyping (7401 cases and 8046 controls) was conducted. Other study designs, such as family-based association studies and genome-wide linkage and association studies were also reviewed for supportive evidence of implication of endothelial nitric oxide synthase gene in diabetic nephropathy. The meta-analysis showed that G894T is significantly associated with diabetic nephropathy and diabetes leading to severe nephropathy in type 2 diabetics and in East Asians, respectively. Concerning the 4b/a polymorphism and its relationship to diabetes leading to severe nephropathy, a significant association was shown for East Asians. Heterogeneity between studies was in general high. There was no differential magnitude of effect in large versus small studies. One genome-wide linkage scan provided evidence of linkage nearby the endothelial nitric oxide synthase locus. Studies exploring gene and environment interactions with endothelial nitric oxide synthase polymorphisms may help understand better the genetics of diabetic nephropathy.

The natural progression of kidney injury in young type 1 diabetic patients

Diabetes is the most common cause of end-stage renal disease in industrialized countries. This article describes the structural changes in early diabetic nephropathy and the relationship with renal functional parameters, blood pressure, and albumin excretion. The detrimental influence of sustained hyperglycemia and/or glycemic fluctuations on renal structural change has been well documented. Tight glycemic control is paramount to preventing the development, and even the regression, of renal lesions. As much of the renal injury from diabetes occurs in clinical silence before symptoms or laboratory findings of renal injury are evident, finding early markers of risk is imperative so that nephropathy can be prevented. Currently, the only clinical surrogate marker of diabetic renal injury available is microalbuminuria. However, given the reports of regression of microalbuminuria back to normoalbuminuria, the reliability of this tool as an indicator of risk has been questioned. The need for alternative, noninvasive surrogate markers is described in this report.

Diabetic nephropathy

Diabetic nephropathy is the leading cause of chronic renal disease and a major cause of cardiovascular mortality. Diabetic nephropathy has been categorized into stages: microalbuminuria and macroalbuminuria. The cut-off values of micro- and macroalbuminuria are arbitrary and their values have been questioned. Subjects in the upper-normal range of albuminuria seem to be at high risk of progression to micro- or macroalbuminuria and they also had a higher blood pressure than normoalbuminuric subjects in the lower normoalbuminuria range. Diabetic nephropathy screening is made by measuring albumin in spot urine. If abnormal, it should be confirmed in two out three samples collected in a three to six-months interval. Additionally, it is recommended that glomerular filtration rate be routinely estimated for appropriate screening of nephropathy, because some patients present a decreased glomerular filtration rate when urine albumin values are in the normal range. The two main risk factors for diabetic nephropathy are hyperglycemia and arterial hypertension, but the genetic susceptibility in both type 1 and type 2 diabetes is of great importance. Other risk factors are smoking, dyslipidemia, proteinuria, glomerular hyperfiltration and dietary factors. Nephropathy is pathologically characterized in individuals with type 1 diabetes by thickening of glomerular and tubular basal membranes, with progressive mesangial expansion (diffuse or nodular) leading to progressive reduction of glomerular filtration surface. Concurrent interstitial morphological alterations and hyalinization of afferent and efferent glomerular arterioles also occur. Podocytes abnormalities also appear to be involved in the glomerulosclerosis process. In patients with type 2 diabetes, renal lesions are heterogeneous and more complex than in individuals with type 1 diabetes. Treatment of diabetic nephropathy is based on a multiple risk factor approach, and the goal is retarding the development or progression of the disease and to decrease the subject's increased risk of cardiovascular disease. Achieving the best metabolic control, treating hypertension (<130/80 mmHg) and dyslipidemia (LDL cholesterol <100 mg/dl), using drugs that block the renin-angiotensin-aldosterone system, are effective strategies for preventing the development of microalbuminuria, delaying the progression to more advanced stages of nephropathy and reducing cardiovascular mortality in patients with diabetes.

Modern-day clinical course of type 1 diabetes mellitus after 30 years' duration: the diabetes control and complications trial/epidemiology of diabetes interventions and complications and Pittsburgh epidemiology of diabetes complications experience (1983-2005)

BACKGROUND

Clinical treatment goals of type 1 diabetes mellitus (T1DM) have changed since the Diabetes Control and Complications Trial (DCCT) demonstrated reduced long-term complications with intensive diabetes therapy. There have been few longitudinal studies to describe the clinical course of T1DM in the age of intensive therapy. Our objective was to describe the current-day clinical course of T1DM.

METHODS

An analysis of the cumulative incidence of long-term complications was performed. The DCCT (1983-1993) assigned patients to conventional or intensive therapy. Since 1993, the DCCT has been observational, and intensive therapy was recommended for all patients. The Pittsburgh Epidemiology of Diabetes Complications (EDC) study is an observational study of patients with T1DM from Allegheny County, Pennsylvania. The study population comprised the DCCT T1DM cohort (N = 1441) and a subset of the EDC cohort (n = 161) selected to match DCCT entry criteria. In the DCCT, intensive therapy aimed for a near-normal glycemic level with 3 or more daily insulin injections or an insulin pump. Conventional therapy, with 1 to 2 daily insulin injections, was not designed to achieve specific glycemic targets. Main outcome measures included the incidences of proliferative retinopathy, nephropathy (albumin excretion rate >300 mg/24 h, creatinine level >or=2 mg/dL [to convert to micromoles per liter, multiply by 88.4], or renal replacement), and cardiovascular disease.

RESULTS

After 30 years of diabetes, the cumulative incidences of proliferative retinopathy, nephropathy, and cardiovascular disease were 50%, 25%, and 14%, respectively, in the DCCT conventional treatment group, and 47%, 17%, and 14%, respectively, in the EDC cohort. The DCCT intensive therapy group had substantially lower cumulative incidences (21%, 9%, and 9%) and fewer than 1% became blind, required kidney replacement, or had an amputation because of diabetes during that time.

CONCLUSION

The frequencies of serious complications in patients with T1DM, especially when treated intensively, are lower than that reported historically.

[Diabetic retinopathy risk factors]

Diabetic retinopathy (DR) occurs in about 95% of patients with type 1 diabetes mellitus (DM) and in 60% of type 2 DM patients and it is the main cause of legal blindness in adult people. The aim of this manuscript was to review the main risk factors for DR. The major environmental risk factors are hyperglycemia, high blood pressure levels, and long-term duration of DM. However, not all patients will not develop DR, suggesting the presence of a genetic predisposition to DR, especially for severe forms of DR. Special strategies has been used to evaluate the genetic role in DR. Family studies shown that there is a familial aggregation of DR. Candidates genes have been studied (RAGE; VEGF; PPAR-delta; ICAM-1; ECA; ENPP 1; eNOS) and positive or negative associations with DR were demonstrated. Some chromosomes were also associated to DR in selected populations. Finally, genetic expression studies reinforce the association of candidate genes, or participation of others genes, with the presence of DR. DR is a common complication of DM and, along with non-genetic or environmental risk factors, the identification of genes related to DR could result in more specific and efficient DR treatment.

Association of genetic variants at 3q22 with nephropathy in patients with type 1 diabetes mellitus

Diabetic nephropathy (DN) is the primary cause of morbidity and mortality in patients with type 1 diabetes mellitus (T1DM) and affects about 30% of these patients. We have previously localized a DN locus on chromosome 3q with suggestive linkage in Finnish individuals. Linkage to this region has also been reported earlier by several other groups. To fine map this locus, we conducted a multistage case-control association study in T1DM patients, comprising 1822 cases with nephropathy and 1874 T1DM patients free of nephropathy, from Finland, Iceland, and the British Isles. At the screening stage, we genotyped 3072 tag SNPs, spanning a 28 Mb region, in 234 patients and 215 controls from Finland. SNPs that met the significance threshold of p < 0.01 at this stage were followed up by a series of sample sets. A genetic variant, rs1866813, in the noncoding region at 3q22 was associated with increased risk of DN (overall p = 7.07 x 10(-6), combined odds ratio [OR] of the allele = 1.33). The estimated genotypic ORs of this variant in all Finnish samples suggested a codominant effect, resulting in significant association, with a p value of 4.7 x 10(-5) (OR = 1.38; 95% confidence interval = 1.18-1.62). Additionally, an 11 kb segment flanked by rs62408925 and rs1866813, two strongly correlated variants (r(2) = 0.95), contains three elements highly conserved across multiple species. Independent replication will clarify the role of the associated variants at 3q22 in influencing the risk of DN.

Between hyperfiltration and impairment: demystifying early renal functional changes in diabetic nephropathy

Renal functional changes in diabetic nephropathy conventionally have been linked to progression of urinary albumin excretion. This paradigm was based on historic evidence noting that hyperfiltration occurred in the setting of normoalbuminuria and microalbuminuria and that loss of renal function began in the context of proteinuria. More contemporaneous research findings, using serum cystatin-C-based estimates of glomerular filtration rate (cC-GFR), have challenged this paradigm. Rather, the process of renal function loss appears to begin prior to the onset of proteinuria. In the 2nd Joslin Kidney Study on the Natural History of Microalbuminuria, over one-third of type 1 diabetes (T1DM) patients with microalbuminuria at the time of enrollment already had evidence of mild (cC-GFR<90) or moderate (cC-GFR<60 ml/min) renal function impairment. Understanding the mechanisms underlying this phenomenon of early renal function impairment may allow for interventions directed at altering or retarding early renal function decline. To date, serum uric acid and components of the TNFalpha pathway appear to be involved.

Exclusion of polymorphisms in carnosinase genes (CNDP1 and CNDP2) as a cause of diabetic nephropathy in type 1 diabetes: results of large case-control and follow-up studies

OBJECTIVES

Recently, an association was found between diabetic nephropathy and the D18S880 microsatellite, located in the carnosinase gene (CNDP1) on chromosome 18q. Alleles of this microsatellite encode for a variable number of leucine residues (from four to seven) in the leader peptide of the carnosinase precursor. The frequency of subjects homozygous for the five leucines was higher in control subjects than in case subjects in studies focusing on type 2 diabetic patients. To test whether this finding can be extended to type 1 diabetic patients, we carried out a comprehensive study on association between diabetic nephropathy and the D18S880 microsatellite and 21 additional SNPs that tagged the genomic region containing CNDP1 and CNDP2.

RESEARCH DESIGN AND METHODS

Overall, 1,269 Caucasian patients with type 1 diabetes were included in the study, including 613 patients with normoalbuminuria and a long duration of diabetes, 445 patients with persistent proteinuria, and 211 patients with end-stage renal disease (ESRD). All patients were genotyped for selected polymorphisms, the associations with diabetic nephropathy were tested by a chi(2) test, and odds ratios were calculated.

RESULTS

We did not find any significant association between diabetic nephropathy and any examined genetic markers. The negative findings of the case-control study were supported further by negative findings obtained from the 6-year follow-up study of 445 patients with persistent proteinuria, during which 135 patients developed ESRD.

CONCLUSIONS

Our large, comprehensive study did not find an association between the D18S880 microsatellite or any other polymorphisms in the CNDP2-CNDP1 genomic region and susceptibility for diabetic nephropathy in type 1 diabetes.

Exclusion of Polymorphisms in Carnosinase Genes (CNDP1 and CNDP2) as a Cause of Diabetic Nephropathy in Type 1 Diabetes

OBJECTIVES— Recently, an association was found between diabetic nephropathy and the D18S880 microsatellite, located in the carnosinase gene (CNDP1) on chromosome 18q. Alleles of this microsatellite encode for a variable number of leucine residues (from four to seven) in the leader peptide of the carnosinase precursor. The frequency of subjects homozygous for the five leucines was higher in control subjects than in case subjects in studies focusing on type 2 diabetic patients. To test whether this finding can be extended to type 1 diabetic patients, we carried out a comprehensive study on association between diabetic nephropathy and the D18S880 microsatellite and 21 additional SNPs that tagged the genomic region containing CNDP1 and CNDP2.

RESEARCH DESIGN AND METHODS— Overall, 1,269 Caucasian patients with type 1 diabetes were included in the study, including 613 patients with normoalbuminuria and a long duration of diabetes, 445 patients with persistent proteinuria, and 211 patients with end-stage renal disease (ESRD). All patients were genotyped for selected polymorphisms, the associations with diabetic nephropathy were tested by a χ2 test, and odds ratios were calculated.

RESULTS— We did not find any significant association between diabetic nephropathy and any examined genetic markers. The negative findings of the case-control study were supported further by negative findings obtained from the 6-year follow-up study of 445 patients with persistent proteinuria, during which 135 patients developed ESRD.

CONCLUSIONS— Our large, comprehensive study did not find an association between the D18S880 microsatellite or any other polymorphisms in the CNDP2–CNDP1 genomic region and susceptibility for diabetic nephropathy in type 1 diabetes.

Proinsulin C-peptide abrogates type-1 diabetes-induced increase of renal endothelial nitric oxide synthase in rats

BACKGROUND

Proinsulin C-peptide shows ameliorative effects on diabetic complications, possibly through the production of nitric oxide (NO). On the contrary, increased local availability of NO and expression of endothelial NO synthase (eNOS) in the renal endothelium are shown to be involved in the progression of diabetic nephropathy. The aim of this study was to elucidate the effect of C-peptide and insulin as a reference on the eNOS expression in the early phase of type 1 diabetic rat kidney.

METHODS

Type 1 diabetes in rats was produced by streptozotocin injection and some of the rats were treated with either C-peptide or insulin by the aid of an osmotic pump for 1 week. Conventional biochemical and histological analyses were performed on tissue samples.

RESULTS

The diabetic rats showed hyperglycemia with over 90% reduction of endogenous insulin and C-peptide. Replacement with C-peptide or insulin resulted in recovery of weight lost, but only insulin infusion lowered plasma-glucose concentration. The eNOS protein was localized in glomeruli and endothelial cells of arterioles, and its amounts in the kidneys, but not in the lungs, of diabetic rats was increased. Replacement with C-peptide or insulin-abrogated diabetes-induced increase of renal eNOS protein.

CONCLUSION

The results indicate that C-peptide suppresses diabetes-induced abnormal renal eNOS expression, by which C-peptide may exert beneficial effects on diabetic nephropathy.

Hospitalization for vascular complications in childhood onset type 1 diabetes--effects of gender and age at onset

AIMS

To study the cumulative incidence of hospitalization for severe diabetic vascular complications in childhood onset type 1 diabetes patients with special regards to age at onset and gender.

METHODS

The Swedish Childhood Diabetes Register (SCDR) was linked to the Swedish Hospital Discharge Register up to 31 December 2004. The following diagnoses were traced: diabetic kidney disease, myocardial infarction, stroke, lower limb arterial disease and diabetes with multiple complications. Cox proportional hazards survival method was applied with the following covariates: maternal age, birthweight deviation from gestational week standard, age at onset and gender.

RESULTS

Until 31 December 9974 children had been followed for at least 10 years corresponding to 141 839 person years at risk and 103 (7.3 per 1000 person years) had been hospitalized at least once at the maximum duration of follow-up of 26 years. Diabetic kidney disease was the most common cause of hospitalization and 63 patients had more than one diabetic complication. Female gender (RR=2.02, 95% CI=1.05-3.89) and age at onset of diabetes (RR=1.37, 95% CI=1.20-1.56) were significant risk factors for severe complication.

CONCLUSIONS

Hospitalization for severe diabetic complications at a maximum follow-up of 26 years is rather low in Sweden. There is a higher hospitalization rate among females than among males, and also among patients diagnosed with diabetes after 10 years of age than among patients diagnosed before the age of 10 years.

Risk of microalbuminuria and progression to macroalbuminuria in a cohort with childhood onset type 1 diabetes: prospective observational study

OBJECTIVES

To describe independent predictors for the development of microalbuminuria and progression to macroalbuminuria in those with childhood onset type 1 diabetes.

DESIGN

Prospective observational study with follow-up for 9.8 (SD 3.8) years.

SETTING

Oxford regional prospective study.

PARTICIPANTS

527 participants with a diagnosis of type 1 diabetes at mean age 8.8 (SD 4.0) years.

MAIN OUTCOME MEASURES

Annual measurement of glycated haemoglobin (HbA1c) and assessment of urinary albumin:creatinine ratio.

RESULTS

Cumulative prevalence of microalbuminuria was 25.7% (95% confidence interval 21.3% to 30.1%) after 10 years of diabetes and 50.7% (40.5% to 60.9%) after 19 years of diabetes and 5182 patient years of follow-up. The only modifiable adjusted predictor for microalbuminuria was high HbA1c concentrations (hazard ratio per 1% rise in HbA1c 1.39, 1.27 to 1.52). Blood pressure and history of smoking were not predictors. Microalbuminuria was persistent in 48% of patients. Cumulative prevalence of progression from microalbuminuria to macroalbuminuria was 13.9% (12.9% to 14.9%); progression occurred at a mean age of 18.5 (5.8) years. Although the sample size was small, modifiable predictors of macroalbuminuria were higher HbA(1c) levels and both persistent and intermittent microalbuminuria (hazard ratios 1.42 (1.22 to 1.78), 27.72 (7.99 to 96.12), and 8.76 (2.44 to 31.44), respectively).

CONCLUSION

In childhood onset type 1 diabetes, the only modifiable predictors were poor glycaemic control for the development of microalbuminuria and poor control and microalbuminuria (both persistent and intermittent) for progression to macroalbuminuria. Risk for macroalbuminuria is similar to that observed in cohorts with adult onset disease but as it occurs in young adult life early intervention in normotensive adolescents might be needed to improve prognosis.

A longitudinal study of risk factors for incident albuminuria in diabetic American Indians: the Strong Heart Study

BACKGROUND

There have been no studies that use longitudinal data with more than 2 measurements and methods of longitudinal data analysis to identify risk factors for incident albuminuria over time more effectively.

STUDY DESIGN

Longitudinal study.

SETTINGS & PARTICIPANTS

A subgroup of participants in the Strong Heart Study, a population-based sample of American Indians, in central Arizona, Oklahoma, and North and South Dakota. Participants with diabetes without albuminuria were followed up for a mean of 4 years.

PREDICTORS

Age, sex, study center, high-density lipoprotein and low-density lipoprotein cholesterol levels, triglyceride level, body mass index, systolic blood pressure, use of antihypertensive medication, smoking, hemoglobin A(1c) level, fasting glucose level, type of diabetes therapy, diabetes duration, plasma creatinine level, and urinary albumin-creatinine ratio (UACR).

OUTCOMES & MEASUREMENTS

Albuminuria was defined as UACR of 30 mg/g or greater. Urine creatinine and albumin were measured by using the picric acid method and a sensitive nephelometric technique, respectively.

RESULTS

Of 750 and 568 participants with diabetes without albuminuria and with normal plasma creatinine levels at the first and second examinations, 246 and 132 developed albuminuria by the second and third examinations, respectively. Incident albuminuria was predicted by baseline UACR, fasting glucose level, systolic blood pressure, plasma creatinine level, study center, current smoking, and use of angiotensin-converting enzyme inhibitors and antidiabetic medications. UACR of 10 to 30 mg/g increased the odds of developing albuminuria 2.7-fold compared with UACR less than 5 mg/g.

LIMITATIONS

Single random morning urine specimen.

CONCLUSIONS

Many risk factors identified for incident albuminuria can be modified. Control of blood pressure and glucose level, smoking cessation, and use of angiotensin-converting enzyme inhibitors may reduce the incidence of albuminuria.

Familial risk factors for microvascular complications and differential male-female risk in a large cohort of American families with type 1 diabetes

CONTEXT

Type 1 diabetes (T1D) complications are responsible for much of the disease morbidity. Evidence suggests that familial factors exert an influence on susceptibility to complications.

OBJECTIVES

We investigated familial risk factors and gender differences for retinopathy, nephropathy, and neuropathy.

DESIGN AND SETTING

This study was a case-control design nested on a cohort of T1D families. We collected data (questionnaire, medical records) starting in 1988. Follow-up has been ongoing since 2004.

PATIENTS

There were 8114 T1D patients among 6707 families. All patients had T1D onset age younger than 30 yr and required insulin treatment. Patients who remained without a complication after more than 15 yr of diabetes were considered to be without that complication for our analyses.

RESULTS

A complication in a sibling increased the risk for that complication among probands: odds ratio 9.9 (P < 0.001) for retinopathy, 6.2 for nephropathy (P < 0.001), and 2.2 for neuropathy (P < 0.05). Compared with male probands, a female T1D proband had 1.7-fold higher retinopathy risk (P < 0.001) and 2-fold higher neuropathy risk (P < 0.001). T1D cases with onset between ages 5 and 14 yr had an increased complications risk compared with subjects diagnosed either at a very young age or after puberty. The presence of one complication significantly increased the risk for others. If a parent had type 2 diabetes, the risk for nephropathy increased (odds ratio 1.9, P < 0.01, but T1D in a parent did not increase the risk).

CONCLUSIONS

We confirmed that familial factors influence T1D microvascular pathologies, suggesting a shared genetic basis for complications, perhaps independent of T1D susceptibility. We also found an unexpected increased female risk for complications.

Recent advancement of understanding pathogenesis of type 1 diabetes and potential relevance to diabetic nephropathy

Type 1 diabetes mellitus is an autoimmune disease characterized by progressive destruction of pancreatic beta cells by genetic and environmental factors which leads to an absolute dependence of insulin for survival and maintenance of health. Although the majority of mechanisms of beta cell destruction remain unclear, many molecules, including proinflammatory cytokines and chemokines such as tumor necrosis factor alpha and monocyte chemoattractant protein-1, are implicated in the development of beta cell damage. Furthermore, beta cell destruction is enhanced by the Th1 and Th17 subsets of CD4+ T cells. In contrast, there are mechanisms involved in the maintenance of peripheral tolerance by regulatory T cells, the function of which depends on the pleiotropic cytokine transforming growth factor beta. Development and progression of renal injuries in patients with diabetic nephropathy are also associated with several growth factors and proinflammatory cytokines, including tumor necrosis factor alpha, insulin-like growth factor-1, monocyte chemoattractant protein-1, vascular endothelial growth factor, and transforming growth factor beta. Although the pathogenic mechanisms underlying type 1 diabetes and diabetic nephropathy are principally different, i.e., autoimmunity and inflammation, some common factors, including susceptibility genes and proinflammatory cytokines, are involved in both mechanisms, including infiltrating cell recruitment, upregulation of other cytokines and chemokines, or apoptosis.

WITHDRAWN: Angiotensin converting enzyme inhibitors in normotensive diabetic patients with microalbuminuria

BACKGROUND

Renal disease is a serious complication of diabetes mellitus.

OBJECTIVES

To examine whether the progression of early diabetic renal disease to end-stage renal failure may be slowed by the use of angiotensin converting enzyme inhibitors for reasons other than their antihypertensive properties, so that they have value in the treatment of normotensive diabetics with microalbuminuria.

SEARCH STRATEGY

Medline was searched for English language reviews and randomised controlled trials. Personal reference lists, and reference lists of retrieved studies were also used.

SELECTION CRITERIA

Randomised controlled trials with separate identifiable results for initially normotensive diabetic patients, who received angiotensin converting enzyme inhibitors for at least one year and were compared with controls.

DATA COLLECTION AND ANALYSIS

Meta-analyses were performed on the results of 12 randomised controlled trials with a variety of patient inclusion and exclusion criteria. One further study met all conditions for inclusion but did not provide data in useable form for meta-analyses.

MAIN RESULTS

Albumin excretion rate fell for patients on angiotensin converting enzyme inhibition in 12 of the 13 studies but did so for only two of the 13 groups on placebo. Treatment provided a significant reduction in albumin excretion rate in both insulin dependent diabetes mellitus and non insulin dependent diabetes mellitus. Treatment with either captopril, enalapril or lisinopril reduced albumin excretion rate in comparison with control patients.A significantly greater lowering of blood pressure was experienced by initially normotensive patients in the angiotensin converting enzyme inhibitor than in the placebo group. Average glycosylated haemoglobin fell a little in the treated patients and rose in the controls, the difference being just significant. The difference in changes in glomerular filtration rate did not reach statistical significance.

AUTHORS' CONCLUSIONS

Inhibition of angiotensin converting enzyme can arrest or reduce the albumin excretion rate in microalbuminuric normotensive diabetics, as well as reduce or prevent an increase in blood pressure. But, given the drop in blood pressure in patients on angiotensin converting enzyme inhibitors, it is not certain that the reduction of albumin excretion rate is due to a separate renal effect. A direct link with postponement of end-stage renal failure has not been demonstrated. There appear to be no substantial side effects.

Six-year incidence of proteinuria in type 1 diabetic African Americans

OBJECTIVE

We sought to report the 6-year incidence of proteinuria and associated risk factors in African Americans with type 1 diabetes.

RESEARCH DESIGN AND METHODS

African Americans (n = 483) with type 1 diabetes were reexamined in a 6-year follow-up study. Proteinuria and creatinuria were measured in 4-h timed urine specimens obtained at initial and follow-up visits. Other evaluations included a structured clinical interview, ocular examination, masked grading of seven stereoscopic fundus photographs, blood pressure measurements, blood assays, and administration of the Beck Depression Inventory (BDI).

RESULTS

Over the 6-year period, 117 (42.9%) of the 473 patients at risk developed "any" proteinuria, defined as either microalbuminuria (26.0%) or overt (16.9%) proteinuria; 87 (23.5%) progressed from micro- or no albuminuria to overt proteinuria and 39 (8.7%) to end-stage renal disease; and 40 (20.6%) regressed. Peak incidence of any proteinuria occurred for patients who were 10-14 years of age or had 5-10 years of diabetes duration at baseline. Multiple regression analysis showed that baseline albumin excretion rate (AER), systemic hypertension, blood cholesterol, and high BDI depression scores were significant and independent risk factors for incidence of any proteinuria.

CONCLUSIONS

In African Americans with type 1 diabetes, the 6-year incidence of proteinuria is high, particularly among young patients and those with a relatively short duration of diabetes at baseline. Baseline AER is the strongest predictor for incidence of any proteinuria.

Pre-pubertal induction of experimental diabetes protects against early renal macrophage infiltration

The present study was undertaken to identify whether the age at induction of experimental diabetes modifies macrophage infiltration in the kidney. Renal macrophage infiltration was studied 10 days after the induction of experimental diabetes in 4-week-old pre-pubertal and 12-week-old adult male rats of normotensive [Wistar-Kyoto (WKY) rats] and hypertensive (spontaneously hypertensive rats, SHRs) background. Renal macrophage infiltration was evaluated by immunohistochemistry for ED1. Plasma glucose levels were similar in all diabetic groups. Adult SHRs were hypertensive, and induction of diabetes did not alter blood pressure (BP) in any group. Induction of diabetes in pre-pubertal rats did not induce macrophage infiltration in the kidney. However, in adult rats, tubulointerstitial macrophage infiltration was increased in both WKY (22.86 +/- 3.93 vs 7.86 +/- 2.16 per high-power field, P < 0.001) and SHR (26.41 +/- 5.91 vs 11.48 +/- 1.23, P < 0.001) groups after induction of diabetes. Glomerular macrophage infiltration was also increased after induction of diabetes in the adult WKY group (1.83 +/- 0.50 vs 1.16 +/- 0.26 per glomerular cross section, P = 0.029), which was not significant in the adult SHRs (2.52 +/- 0.34 vs 1.95 +/- 0.35). We conclude that the pre-pubertal induction of diabetes apparently protects against early renal macrophage infiltration, while the induction of diabetes in adults induces exaggerated macrophage infiltration in the kidney.

A transition care programme which improves diabetes control and reduces hospital admission rates in young adults with Type 1 diabetes aged 15-25 years

AIMS

To determine if a transition support programme for young adults with diabetes could maintain attendance at a specialist clinic, improve diabetes control and reduce acute hospital admissions with diabetic ketoacidosis (DKA) in 15-25-year-olds with Type 1 diabetes.

METHODS

A transition coordinator/diabetes educator arranged booking and rebooking of appointments for a young adult diabetes clinic based in an adult hospital between July 2001 and March 2006. An after-hours phone support service was initiated. Data collected included source of referral, frequency of clinic attendance and HbA1c at each visit. Numbers of admissions and readmissions with DKA, length of stay and HbA1c on admission were recorded.

RESULTS

One hundred and ninety-one young adults were referred. HbA1c at initial referral was 9.3 +/- 2.17%. HbA1c significantly improved to 8.8 +/- 1.9% (P < 0.001) after a median of five visits with a statistically significant fall in HbA1c of 0.13% per visit (P = 0.01). The greatest improvements were seen in those with starting HbA1c > 11% (-2.5 +/- 2.3%, P < 0.001). Eighty-two percent had attended appointments in the last 6 months. There was a significant reduction in DKA admissions falling by 1/3 (P = 0.05), and in readmissions a significant reduction in length of stay (-3.6 days, P = 0.02), over 3.5 years.

CONCLUSIONS

If young adults are appropriately supported in adult services, clinic attendance is maintained, diabetes control is improved and hospital admission rates with DKA are reduced. The cost savings from reduced admissions covered the costs of the programme.

Genetic risk factors for diabetic nephropathy on chromosomes 6p and 7q identified by the set-association approach

AIMS/HYPOTHESIS

In the present study we investigated potential associations of a set of 45 single nucleotide polymorphisms (SNP) in 20 candidate genes on eight chromosomes with diabetic nephropathy (DN) in type 2 diabetes mellitus. We aimed to compare two methodological approaches suitable for analysing susceptibility to complex traits: single- and multi-locus analyses.

MATERIALS AND METHODS

The study comprised a total of 647 subjects in one of three groups: diabetes with or without DN, or no diabetes. Genotypes were detected by PCR-based methodology (PCR only, PCR plus RFLP, or allele-specific PCR). Haplotypes were inferred in silico. Set association (tested using SUMSTAT software) was used for multilocus analysis.

RESULTS

After correction for multiple comparisons, only one SNP, in the gene encoding the receptor of advanced glycation end products, AGER 2184A/G (gene symbol formerly known as RAGE) showed a significant association with DN (p = 0.0006) in single-locus analysis. In multi-locus analysis, six SNPs exhibited a significant association with DN: four SNPs on chromosome 6p (AGER 2184A/G, LTA 252A/G, EDN1 8002G/A and AGER -429T/C) and two SNPs on chromosome 7q (NOS3 774C/T and NOS3 E298D), omnibus p = 0.033. Haplotype analysis revealed significant differences between DN and control groups in haplotype frequencies on chromosome 6 (p = 0.0002); however, there were no significant difference in the frequencies of the NOS3 haplotypes on chromosome 7. Logistic regression analysis identified SNPs AGER 2184A/G and NOS3 774C/T, together with diabetes duration and HbA1c, as significant predictors of DN. Testing for interactions between SNPs on chromosomes 6 and 7 did not provide significant evidence for epistatic interaction.

CONCLUSIONS/INTERPRETATION

Using the set-association approach we identified significant associations of several SNPs on chromosomes 6 and 7 with DN. The single- and multi-locus analyses represent complementary methods.

Gene discovery in diabetic nephropathy

Diabetic nephropathy affects approximately one third of diabetic patients and is the leading cause of end-stage renal disease. Identification of genetic susceptibility factors contributing to the development of diabetic nephropathy could facilitate prediction, development of improved treatments, and prevention of this devastating complication of diabetes. Although investigations to identify the causal genetic variants associated with diabetic nephropathy have been inconclusive, new approaches, including whole genome association scanning, offer hope for the future.

Expression pattern of genes in peripheral blood mononuclear cells in diabetic nephropathy

AIMS

Only one-third of Type 1 diabetes patients develop diabetic nephropathy, and a genetic predisposition is postulated. To obtain more insight into processes that lead to diabetic nephropathy, messenger RNA expression profiles of peripheral blood mononuclear cells from patients with and without diabetic nephropathy were compared.

METHODS

We studied seven male patients with Type 1 diabetes and proteinuria and 12 male patients with Type 1 diabetes and normoalbuminuria after at least 20 years of diabetes duration. The expression of genes was examined using the microarray method with Human Genome U133A Arrays (Affymetrix, Santa Clara, CA, USA). We analysed the expression of all candidate genes suggested to be involved in the pathogenesis of diabetic nephropathy in previously published articles. Altogether, expression of 198 genes was analysed.

RESULTS

We found that thrombospondin 1 (THBS1) and cyclooxygenase 1(COX1) genes were over-expressed in patients with diabetic nephropathy, and matrix metalloproteinase 9 (MMP9) and cyclooxygenase 2 (COX2) genes had lower expression in diabetic nephropathy. For other genes, we did not observe different expression between patients with and without diabetic nephropathy,or the expression was too low for analysis.

CONCLUSIONS

The different gene expression pattern in peripheral blood mononuclear cells in patients with diabetic nephropathy might indicate an important pathway in the pathogenesis of this complication.

Pre-eclampsia but not pregnancy-induced hypertension is a risk factor for diabetic nephropathy in type 1 diabetic women

AIMS/HYPOTHESIS

Our aim was to study whether pre-eclampsia and pregnancy-induced hypertension are predictors of diabetic nephropathy in type 1 diabetic women.

MATERIALS AND METHODS

A total of 203 type 1 diabetic women, who were pregnant between 1988 and 1996 and followed at the Department of Obstetrics and Gynaecology in Helsinki, were re-assessed after an average of 11 years within the nationwide, multi-centre Finnish Diabetic Nephropathy Study. Diabetic nephropathy was defined as microalbuminuria, macroalbuminuria or end-stage renal disease.

RESULTS

Patients with prior pre-eclampsia had diabetic nephropathy more often than patients with a normotensive pregnancy (diabetic nephropathy vs normal albumin excretion rate: 41.9% vs 8.9%; p<0.001), whereas patients with a history of pregnancy-induced hypertension did not (10.3% vs 8.9%; p=0.81). CHD was more prevalent in patients with a history of pre-eclampsia than in patients with a normotensive pregnancy (12.2% vs. 2.2%; p=0.03). Pre-eclampsia (odds ratio [OR] 7.7, 95% CI 1.6-36.1; p=0.01) and HbA(1c) (OR 2.0, 95% CI 1.1-3.8; p<0.05) were associated with incident diabetic nephropathy even when adjusted for follow-up time, BMI, smoking, diabetes duration and age.

CONCLUSIONS/INTERPRETATION

These data suggest that a history of pre-eclamptic pregnancy but not pregnancy-induced hypertension is associated with an elevated risk of diabetic nephropathy.

Renal protection in diabetes: role of glycemic control

Diabetes is the most common cause of ESRD in Western countries. This article describes the impact of glycemic control in the various stages of the disease and considers the impact of tight glycemic control on the development and progression of diabetic nephropathy (DN). The Diabetes Control and Complications Trial and the United Kingdom Prospective Diabetic Study have demonstrated in type 1 and type 2 diabetes that intensive glycemic control significantly reduces the risk for development of microalbuminuria. Although observational studies suggest an impact of glycemia also on the progression of DN, fewer data are available on the impact of improved metabolic control in secondary prevention. The long-term follow-up of the patients who participated in the Diabetes Control and Complications Trial (Epidemiology of Diabetes Interventions and Complications Study) demonstrated a sustained effect of previous tight glycemic control on both development and progression of DN. Finally, long-term normoglycemia, achieved by pancreas transplantation, is able not only to prevent the development of early diabetic glomerulopathy in kidney transplant recipients but also to halt progression and induce regression of the established diabetic renal lesions in nonuremic patients. Taken together, these studies strongly demonstrate that improvement in glucose control is the most important therapeutic approach in primary prevention. Tight glycemic control also is important in slowing progression of DN, and if blood glucose is normalized, then regression of DN can be achieved. Therefore, a target of glycated hemoglobin levels <7% should be recommended in all patients with diabetes.

Using individualized predictive disease modeling to identify patients with the potential to benefit from a disease management program for diabetes mellitus

Diabetes is an increasing health problem, but efforts to handle this pandemic by disease management programs (DMP) have shown conflicting results. Our hypothesis is that, in addition to a program's content and setting, the choice of the right patients is crucial to a program's efficacy and effectiveness. We used individualized predictive disease modeling (IPDM) on a cohort of 918 patients with type 2 diabetes to identify those patients with the greatest potential to benefit from inclusion in a DMP. A portion of the patients (4.7%) did not have even a theoretical potential for an increase in life expectancy and would therefore be unlikely to benefit from a DMP. Approximately 16.1% had an increase in life expectancy of less than half a year. Stratification of the entire cohort by surrogate parameters like preventable 10-year costs or gain in life expectancy was much more effective than stratification by classical clinical parameters such as high HbA1c level. Preventable costs increased up to 50.6% (or 1,010 per patient (1 = US dollars 1.28), p < 0.01) and life expectancy increased up to 54.8% (or 2.3 years, p < 0.01). IPDM is a valuable strategy to identify those patients with the greatest potential to avoid diabetes-related complications and thus can improve the overall effectiveness and efficacy of DMPs for diabetes mellitus.

Diabetic nephropathy: worldwide epidemic and effects of current treatment on natural history

Diabetic nephropathy has become a worldwide epidemic, accounting for approximately one third of all cases of end-stage renal disease. With increasing prevalence of diabetes particularly in Asia, and a global prevalence of microalbuminuria of 39%, the problem is expected to grow. Improved management of diabetes aimed at improved glycemic control, to avoid initiation of diabetic nephropathy, and antihypertensive treatment blocking the renin-angiotensin system, to avoid its progression, need to be implemented, particularly in high-risk patients.

Amelioration of established diabetic nephropathy by combined treatment with SMP-534 (antifibrotic agent) and losartan in db/db mice

BACKGROUND/AIMS

Diabetic nephropathy is the main cause of end-stage renal disease. Previously we have demonstrated that SMP-534 (an antifibrotic agent) prevents the development of diabetic nephropathy in db/db mouse and that combined treatment with SMP-534 and losartan (antihypertensive agents) markedly prevents the development of diabetic nephropathy compared with single treatment. SMP-534 or losartan was prophylactically administered to db/db mice before the onset of diabetic nephropathy. In the present study, we evaluated the efficacy of combined treatment when administration was started after the onset of diabetic nephropathy.

METHODS

db/db mice were raised untreated until 17 weeks of age, by which time increase of urinary albumin was noted, and then treated with SMP-534 and/or losartan for another 8 weeks. Biochemical and histological analyses were performed at 25 weeks of age.

RESULTS

Combined treatment with SMP-534 and losartan markedly prevented the increase of urinary albumin and ameliorated the progression of mesangial matrix expansion, even when administration was started long after the increase of urinary albumin.

CONCLUSION

The study results indicate that a combination of SMP-534 and losartan might be a valuable therapeutic approach for the treatment of diabetic nephropathy even when administration is started after the onset of diabetic nephropathy.