Sex-related differences in the long-term risk of microvascular complications by age at onset of type 1 diabetes

Chemokines in diabetic eye disease

BACKGROUND

Diabetic eye disease is a common micro-vascular complication of diabetes and a leading cause of decreased vision and blindness in people of working age worldwide.Although previous studies have shown that chemokines system may be a player in pathogenesis of diabetic eye disease, it is unclear which chemokines play the most important role.To date, there is no meta-analysis which has investigated the role of chemokines in diabetic eye disease.We hope this study will contribute to a better understanding of both the signaling pathways of the chemokines in the pathophysiological process, and more reliable therapeutic targets for diabetic eye disease.

METHODS

Embase, PubMed, Web of Science and Cochrane Library systematically searched for relevant studies from inception to Sep 1, 2023. A random-effect model was used and standardized mean differences (SMDs) and 95% confidence intervals (CIs) were calculated to summarize the associated measure between chemokines concentrations and diabetic eye disease. Network meta-analysis to rank chemokines-effect values according to ranked probabilities.

RESULTS

A total of 33 different chemokines involving 11,465 subjects (6559 cases and 4906 controls) were included in the meta-analysis. Results of the meta-analysis showed that concentrations of CC and CXC chemokines in the diabetic eye disease patients were significantly higher than those in the controls. Moreover, network meta-analysis showed that the effect of CCL8, CCL2, CXCL8 and CXCL10 were ranked highest in terms of probabilities. Concentrations of CCL8, CCL2, CXCL8 and CXCL10 may be associated with diabetic eye disease, especially in diabetic retinopathy and diabetic macular edema.

CONCLUSION

Our study suggests that CCL2 and CXCL8 may play key roles in pathogenesis of diabetic eye disease. Future research should explore putative mechanisms underlying these links, with the commitment to develop novel prophylactic and therapeutic for diabetic eye disease.

Genetic and epigenetic background of diabetic kidney disease

Diabetic kidney disease (DKD) is a severe diabetic complication that affects up to half of the individuals with diabetes. Elevated blood glucose levels are a key underlying cause of DKD, but DKD is a complex multifactorial disease, which takes years to develop. Family studies have shown that inherited factors also contribute to the risk of the disease. During the last decade, genome-wide association studies (GWASs) have emerged as a powerful tool to identify genetic risk factors for DKD. In recent years, the GWASs have acquired larger number of participants, leading to increased statistical power to detect more genetic risk factors. In addition, whole-exome and whole-genome sequencing studies are emerging, aiming to identify rare genetic risk factors for DKD, as well as epigenome-wide association studies, investigating DNA methylation in relation to DKD. This article aims to review the identified genetic and epigenetic risk factors for DKD.

Role of sex hormones in diabetic nephropathy

Diabetic nephropathy (DN) is the most common microvascular complication in diabetes and one of the leading causes of end-stage renal disease. The standard treatments for patients with classic DN focus on blood glucose and blood pressure control, but these treatments can only slow the progression of DN instead of stopping or reversing the disease. In recent years, new drugs targeting the pathological mechanisms of DN (e.g., blocking oxidative stress or inflammation) have emerged, and new therapeutic strategies targeting pathological mechanisms are gaining increasing attention. A growing number of epidemiological and clinical studies suggest that sex hormones play an important role in the onset and progression of DN. Testosterone is the main sex hormone in males and is thought to accelerate the occurrence and progression of DN. Estrogen is the main sex hormone in females and is thought to have renoprotective effects. However, the underlying molecular mechanism by which sex hormones regulate DN has not been fully elucidated and summarized. This review aims to summarize the correlation between sex hormones and DN and evaluate the value of hormonotherapy in DN.

Potential Plasma Metabolite Biomarkers of Diabetic Nephropathy: Untargeted Metabolomics Study

Diabetic nephropathy (DN) is one of the specific complications of diabetes mellitus and one of the leading kidney-related disorders, often requiring renal replacement therapy. Currently, the tests commonly used for the diagnosis of DN, albuminuria (AU) and glomerular filtration rate (GFR), have limited sensitivity and specificity and can usually be noted when typical morphological changes in the kidney have already been manifested. That is why the extreme urgency of the problem of early diagnosis of this disease exists. The untargeted metabolomics analysis of blood plasma samples from 80 patients with type 1 diabetes and early and late stages of DN according to GFR was performed using direct injection mass spectrometry and bioinformatics analysis for diagnosing signatures construction. Among the dysregulated metabolites, combinations of 15 compounds, including amino acids and derivatives, monosaccharides, organic acids, and uremic toxins were selected for signatures for DN diagnosis. The selected metabolite combinations have shown high performance for diagnosing of DN, especially for the late stage (up to 99%). Despite the metabolite signature determined for the early stage of DN being characterized by a diagnostic performance of 81%, these metabolites as potential biomarkers might be useful in the evaluation of treatment of the disease, especially at early stages that may reduce the risk of kidney failure development.

Incidence rate patterns, cumulative incidence, and time trends for moderate and severe albuminuria in individuals diagnosed with type 1 diabetes aged 0-14 years: a population-based retrospective cohort study

BACKGROUND

The incidence and temporal trends of moderate and severe albuminuria during recent decades are poorly described in type 1 diabetes. We aimed to assess diabetes duration-specific incidence rates, cumulative incidence, and secular trends of albuminuria in type 1 diabetes in Finland.

METHODS

We conducted a population-based, retrospective cohort study of a stratified random sample (n=1500) of all individuals diagnosed with type 1 diabetes before age 15 years during 1970-99 in Finland. The sampling frame was the database of the Finnish Institute for Health and Welfare. Individuals with an atypical clinical course, presentation of non-diabetic kidney disease, insufficient albumin excretion rate measurements, or unavailable medical records were excluded (final sample n=1430). Study participants were followed up until death, the event of interest (moderate or severe albuminuria or kidney failure), or the most recent event-free date. Medical records retrieved up to Dec 31, 2020 were systematically reviewed for albuminuria determinations. Moderate and severe albuminuria were categorised on the basis of international reference limits (two of three consecutive urine samples). Kidney failure was defined as dialysis treatment or kidney transplant. Cohorts defined by calendar year of diabetes diagnosis (1970-79, 1980-89, and 1990-99) were assessed. Patterns of duration-specific incidences were evaluated by fitting generalised additive models to the data, which were split into multiple observations of half-year duration. Cumulative incidences were calculated with Kaplan-Meier analysis. In analyses with kidney failure as the endpoint, competing risk for mortality was incorporated.

FINDINGS

In our stratified random sample, 462 individuals were diagnosed with diabetes in 1970-79, 481 were diagnosed in 1980-89, and 487 were diagnosed in 1990-99. The incidence rate pattern of severe albuminuria changed over time; a peak at 15-19 years since diabetes onset in the 1970-79 cohort was not replicated in those diagnosed later. In the combined 1980-99 diagnosis-year cohorts, the incidence rate rose during the first 14 years after diabetes onset, after which it levelled off to a plateau. Between the 1970-79 and 1980-89 diabetes diagnosis cohorts, the cumulative incidence of severe albuminuria had approximately halved (hazard ratio [HR] 0·55 [95% CI 0·42-0·72] with the 1970-79 cohort as reference, p<0·0001), whereas, between the 1980-89 and 1990-99 cohorts, no further decrease was observed (HR 0·83 [0·54-1·26] with the 1980-89 cohort as reference, p=0·38). The 25-year cumulative incidence for severe albuminuria was 26·8% (22·6-30·8) in the 1970-79 diagnosis cohort, 12·0% (9·0-15·0) in the 1980-89 cohort, and 10·8% (6·7-14·6) in the 1990-99 cohort. 15 years after onset of severe albuminuria, cumulative progression rate from severe albuminuria to kidney failure was 35·2% (27·4-43·0) in the 1970-79 cohort and 35·6% (24·3-47·0) in the 1980-99 cohorts combined (Gray's test p=0·37). In the cohorts with data on moderate albuminuria (1980-89 and 1990-99), cumulative incidence of moderate albuminuria showed no calendar effect between the earlier and later cohorts (HR 0·99 [0·78-1·28] with the 1980-89 cohort as reference, p=0·97). The incidence rate of moderate albuminuria increased until 10 years after diabetes onset, then remained mostly stable until starting to decrease at around 25 years after diabetes onset.

INTERPRETATION

Our analyses show that the cumulative incidence of severe albuminuria has decreased between 1970-79 and 1980-99; however, whether this decrease solely denotes a delay in albuminuria, or also a true prevention of albuminuria, needs to be investigated further. Nevertheless, diabetic kidney disease remains a significant complication of type 1 diabetes. Due to the robust association of diabetic kidney disease with premature mortality, novel therapies to improve prognosis are needed.

FUNDING

Folkhälsan Research Foundation, Medical Society of Finland, Wilhelm and Else Stockmann Foundation, Finnish Diabetes Research Foundation, Waldemar von Frenckell Foundation, Liv och Hälsa Society, Academy of Finland, and Novo Nordisk Foundation.

TRANSLATIONS

For the Finnish and Swedish translations of the abstract see Supplementary Materials section.

Intact mitochondrial substrate efflux is essential for prevention of tubular injury in a sex-dependent manner

The importance of healthy mitochondrial function is implicated in the prevention of chronic kidney disease (CKD) and diabetic kidney disease (DKD). Sex differences also play important roles in DKD. Our previous studies revealed that mitochondrial substrate overload (modeled by homozygous deletion of carnitine acetyl-transferase [CrAT]) in proximal tubules causes renal injury. Here, we demonstrate the importance of intact mitochondrial substrate efflux by titrating the amount of overload through the generation of a heterozygous CrAT-KO model (PT-CrATHET mouse). Intriguingly, these animals developed renal injury similarly to their homozygous counterparts. Mitochondria were structurally and functionally impaired in both sexes. Transcriptomic analyses, however, revealed striking sex differences. Male mice shut down fatty acid oxidation and several other metabolism-related pathways. Female mice had a significantly weaker transcriptional response in metabolism, but activation of inflammatory pathways was prominent. Proximal tubular cells from PT-CrATHET mice of both sexes exhibited a shift toward a more glycolytic phenotype, but female mice were still able to oxidize fatty acid-based substrates. Our results demonstrate that maintaining mitochondrial substrate metabolism balance is crucial to satisfying proximal tubular energy demand. Our findings have potentially broad implications, as both the glycolytic shift and the sexual dimorphisms discovered herein offer potentially new modalities for future interventions for treating kidney disease.

Gender Differences in Diabetic Kidney Disease: Focus on Hormonal, Genetic and Clinical Factors

Diabetic kidney disease (DKD) is one of the most serious complications of both type 1 (T1DM) and type 2 diabetes mellitus (T2DM). Current guidelines recommend a personalized approach in order to reduce the burden of DM and its complications. Recognizing sex and gender- differences in medicine is considered one of the first steps toward personalized medicine, but the gender issue in DM has been scarcely explored so far. Gender differences have been reported in the incidence and the prevalence of DKD, in its phenotypes and clinical manifestations, as well as in several risk factors, with a different impact in the two genders. Hormonal factors, especially estrogen loss, play a significant role in explaining these differences. Additionally, the impact of sex chromosomes as well as the influence of gene-sex interactions with several susceptibility genes for DKD have been investigated. In spite of the increasing evidence that sex and gender should be included in the evaluation of DKD, several open issues remain uncovered, including the potentially different effects of newly recommended drugs, such as SGLT2i and GLP1Ras. This narrative review explored current evidence on sex/gender differences in DKD, taking into account hormonal, genetic and clinical factors.

Sex-related differences in diabetic kidney disease: A review on the mechanisms and potential therapeutic implications

Sexual dimorphism may play a key role in the pathogenesis of diabetic kidney disease (DKD) and explain differences observed in disease phenotypes, responses to interventions, and disease progression between men and women with diabetes. Therefore, omitting the consideration of sex as a biological factor may result in delayed diagnoses and suboptimal therapies. This review will summarize the effects of sexual dimorphism on putative metabolic and molecular mechanisms underlying DKD, and the potential implications of these differences on therapeutic interventions. To successfully implement precision medicine, we require a better understanding of sexual dimorphism in the pathophysiologic progression of DKD. Such insights can unveil sex-specific therapeutic targets that have the potential to maximize efficacy while minimizing adverse events.

Sex-specific association between type 1 diabetes and the risk of end-stage renal disease: a systematic review and meta-analysis

PURPOSE

This meta-analysis was conducted given the inconsistent findings of studies regarding the sex discrepancy in the relationship between type 1 diabetes (T1D) and the risk of end-stage renal disease (ESRD).

METHODS

Articles published on PubMed between January 1, 1966 and March 31, 2019 were systematically retrieved without language restrictions. The included articles all presented sex-specific data of the incidence rate ratio, standardized incidence or mortality ratio, hazard ratio, relative risk, or odds ratio, or provided data to estimate the association between T1D and ESRD or kidney disease-related mortality. The gender-specific effect estimates and pooled ratio (female-to-male) for ESRD and for deaths from T1D-related renal disease were acquired via a random-effects meta-analysis with inverse variance weighting, regardless of heterogeneity evaluated based on the I² statistic.

RESULTS

Nineteen studies, including 122,842 individuals, were finally selected for this meta-analysis. Sex differences in effect estimates were found in ESRD (pooled ratio = 0.81 (95% confidence interval 0.69-0.94)) with considerable heterogeneity (I² = 66.9%), but not in mortality with T1D-associated renal disease.

CONCLUSION

Women with T1D have a lower risk of ESRD compared with that in men, but this finding may be biased by potential confounding factors and must be verified by other well-planned prospective studies.

Sex Differences in Diabetic Kidney Disease

While the global prevalence of both type 1 and type 2 diabetes mellitus is similar in men and women, the consequences of diabetes on associated end-organ complications, including diabetic kidney disease appear to be more sex-specific. Particularly, women with diabetes have higher mortality rates for diabetes-related deaths, and higher prevalence of diabetic kidney disease risk factors such as hypertension, hyperglycemia, obesity, and dyslipidemia. However, the evidence for the impact of sex on diabetic kidney disease prevalence and disease progression is limited and inconsistent. Although most studies agree that the protective effect of the female sex against the development of kidney disease is diminished in the setting of diabetes, the reasons for this observation are unclear. Whether or not sex differences exist in the risk of diabetic kidney disease is also unclear, with studies reporting either higher risk in men, women, or no sex differences. Despite the remaining controversies, some of the factors that associate with sex differences in the risk of diabetic kidney disease are age at onset, and type and duration of diabetes. There is growing appreciation of the importance of sex hormones in the regulation of renal function, with estrogens generally considered to be renoprotective. Although some progress has been made towards better understanding of the mechanisms by which sex hormones play a role in the pathophysiology of diabetic kidney disease, the translational potential of this knowledge is still underappreciated. A better understanding of sex differences in diabetic kidney disease may provide basis for personalized and sex-specific treatment of diabetic kidney disease.

Diabetic retinopathy (DR) among 40 years and older Saudi population with diabetes in Riyadh governorate, Saudi Arabia - A population based survey

Purpose

To present the prevalence and determinants of diabetic retinopathy (DR) among more than 40 years old Saudi population.

Methods

A population based survey was conducted in Riyadh district between 2014 and 2017. All Saudi aged >40 years suffering from diabetes and confirmed in the diabetes register of the Primary Health Center (PHC) were the study population. Representative sample was examined. The Best corrected Visual acuity (BCVA), anterior and posterior segment assessment was performed. Digital fundus camera captured the retinal images. DR was graded into No DR, Non-proliferative DR (Mild, Moderate, Severe) and proliferative DR (PDR). Diabetic macular edema (DME) was separately noted. Sight Threatening Diabetic Retinopathy (STDR) included PDR and/or DME.

Results

We examined 890 persons. The age sex adjusted prevalence of DR was 44.7% (95% CI 44.1 – 45.3). The DR among male was significantly higher than in females. [RR = 1.4 (95% CI 1.02 – 1.8)]. The DR in 60 plus population was higher compared to 40 to 60 years old diabetics [RR = 1.64 (95% CI 1.6 – 1.7), P < 0.001]. The crude prevalence of STDR was 12.4% (95% CI 9.1 – 15.7). Among diabetic with DR, bilateral and unilateral Severe Visual Impairment (SVI) rate were 1% and 1.8%. The coverage of retinal laser treatment for STDR was 6.1%.

Conclusions

The DR among diabetics is high among adult Saudi population. Both DR and STDR were more in males. Visual disabilities among DR cases were few. For early detection and timely management the services need urgent attention.

Establishing equivalent diabetes in male and female Nos3-deficient mice results in a comparable onset of diabetic kidney injury

Clinical studies indicate that sex differences exist in susceptibility for developing diabetic kidney disease (DKD), supporting the need to examine both sexes in animal studies of DKD. Streptozotocin (STZ) is commonly used in male mice to induce diabetes and DKD. However, females are not normally included because their sex hormones partially protect them from STZ-induced islet injury and consequent diabetes. To address this issue, we identified a strategy to induce comparable diabetes in male and female mice using STZ and determined whether both sexes develop equivalent renal injury. Male and female mice lacking the gene for endothelial nitric oxide synthase (Nos3-/-) were made diabetic with five or six low-dose STZ injections, respectively. Groups of male and female mice with equivalent hyperglycemia at week 3 after STZ were assessed for DKD at week 8. STZ-treated male and female Nos3-/- mice maintained comparable hyperglycemia between weeks 3 and 8 had an equivalent increase in HbA1c levels and comparable hypertension. Urine albumin/creatinine levels were elevated eightfold in mice of both sexes at week 8, accompanied by an equivalent loss of podocytes. In diabetic males and females, plasma cystatin C levels and glomerular collagen deposition were similarly increased. Kidney mRNA levels of proinflammatory and profibrotic markers and kidney injury molecule-1 (KIM-1) were equally elevated in males and females, indicating comparable kidney injury. This study shows that equivalent diabetes induces a comparable onset of DKD in male and female Nos3-/- mice, demonstrating that it is possible to include males and females together in studies of DKD.

Influence of Sex on the Progression of Chronic Kidney Disease

The role that sex plays in the development and progression of chronic kidney disease remains a subject of controversy. The lack of clarity in this important area reflects complex interactions between biological factors and cultural and socioeconomic influences that impact the relationship between sex and renal disease. Certainly, additional observational studies are indicated; however, innovative approaches are required to isolate biological processes from cultural influences. Despite these limitations, available data suggest that the progression of renal disease is slower in women than in men and that this sexual dimorphism is primarily due to direct actions of sex hormones on cellular metabolism. The extent to which differences in lifestyle factors between the sexes influence sexual dimorphism in the progression of chronic kidney disease remains to be elucidated.

Decreasing Cumulative Incidence of End-Stage Renal Disease in Young Patients With Type 1 Diabetes in Sweden: A 38-Year Prospective Nationwide Study

OBJECTIVE

Diabetic nephropathy is a serious complication of type 1 diabetes. Recent studies indicate that end-stage renal disease (ESRD) incidence has decreased or that the onset of ESRD has been postponed; therefore, we wanted to analyze the incidence and time trends of ESRD in Sweden.

RESEARCH DESIGN AND METHODS

In this study, patients with duration of type 1 diabetes >14 years and age at onset of diabetes 0-34 years were included. Three national diabetes registers were used: the Swedish Childhood Diabetes Register, the Diabetes Incidence Study in Sweden, and the National Diabetes Register. The Swedish Renal Registry, a national register on renal replacement therapy, was used to identify patients who developed ESRD.

RESULTS

We found that the cumulative incidence of ESRD in Sweden was low after up to 38 years of diabetes duration (5.6%). The incidence of ESRD was lower in patients with type 1 diabetes onset in 1991-2001 compared with onset in 1977-1984 and 1985-1990, independent of diabetes duration.

CONCLUSIONS

The risk of developing ESRD in Sweden in this population is still low and also seems to decrease with time.

Advances in understanding the genetic basis of diabetic kidney disease

Diabetic kidney disease (DKD) is a devastating complication of Type 1 and Type 2 diabetes and leads to increased morbidity and mortality. Earlier work in families has provided strong evidence that heredity is a major determinant of DKD. Previous linkage analyses and candidate gene studies have identified potential DKD genes; however, such approaches have largely been unsuccessful. Genome-wide association studies (GWAS) have made significant contribution in identifying SNPs associated with common complex diseases. Thanks to advanced technology, new analytical approaches, and international research collaborations, many DKD GWASs have reported unique genes, highlighted novel biological pathways and suggested new disease mechanisms. This review summarizes the current state of GWAS technology; findings from GWASs of DKD and its related traits conducted over the past 15 years and discuss the future of this field.

Is sex an influential factor in type-1 diabetes neurofunctional development? A preliminary study

The aim of the study was to evaluate the neurofunctional effect of gender in Type-1 Diabetes Mellitus (T1DM) patients during a Visual Spatial Working Memory (VSWM) task. The study included 28 participants with ages ranging from 17-28 years. Fourteen well-controlled T1DM patients (7 female) and 14 controls matched by age, sex, and education level were scanned performing a block-design VSWM paradigm. Behavioral descriptive analyses and mean comparisons were done, and between-group and condition functional activation patterns were also compared. Whole-brain cumulative BOLD signal (CumBS), voxel-wise BOLD level frequency, Euclidean distance, and divergence indices were also calculated. There were no significant differences between or within-group sex differences for correct responses and reaction times. Functional activation analyses showed that females had activation in more brain regions, and with larger clusters of cortical activations than males. Furthermore, BOLD activation was higher in males. Despite the preliminary nature of the present study given the relatively small sample size, current results acknowledge for the first time that sex might contribute to differences in functional activation in T1DM patients. Findings suggest that sex differences should be considered when studying T1DM-disease development.

Risk Factors Associated With the Development of Nephropathy 10 Years After Diagnosis in Taiwanese Children With Juvenile-Onset Type 1 Diabetes-A Cohort Study From the CGJDES

Objective: To examine the risk factors for diabetic nephropathy (DN) 10 years after the diagnosis of juvenile-onset type 1 diabetes mellitus (T1DM) in a Taiwanese population. Research Design and Methods: This retrospective, observational, longitudinal cohort study of 224 patients with T1DM for >10 years (mean duration 12.6 years) included participants from the Chang Gung Juvenile Diabetes Eye Study Group. The patients received a T1DM diagnosis before the age of 18 years and were treated at the pediatric endocrine department of Chang Gung Memorial Hospital in Taiwan. The epidemiological and laboratory data such as age, sex, duration of diabetes, self-reported smoking, blood pressure, lipid profiles, urinalysis, and glycated hemoglobin A1c (HbA1c) levels were collected from medical records retrospectively for investigating the relationship between the clinical parameters and the development of DN in T1DM. Results: During follow-up, 44 of the 224 patients (19.6%) developed DN, of whom 61.4% were female. Cox proportional hazards model analysis indicated that the female (HR 3.40, 95% CI 1.66-6.96, p = 0.001), smoking (HR 3.60, 95% CI 1.28-10.10, p = 0.015), HbA1c level (HR 1.27, 95% CI 1.07-1.49, p = 0.005), diastolic blood pressure (HR 1.06, 95% CI 1.03-1.09, p < 0.001) were significantly correlated with DN after adjustment for multiple variables. The tight glucose control with multiple daily injections produced 49 % risk reduction (HR 0.51, 95% CI 0.26-0.98, p = 0.043). Conclusions: The risk of DN in patients with juvenile-onset T1DM 10 years after the T1DM diagnosis was increased with female, smoking, high HbA1c, diastolic blood pressure levels and attenuated by intensive therapy.

Incidence of End-Stage Renal Disease in Patients With Type 1 Diabetes

OBJECTIVE

To investigate how risk of end-stage renal disease (ESRD) among patients with type 1 diabetes has changed over time and further how the risk is affected by age, sex, and time period of diagnosis of diabetes.

RESEARCH DESIGN AND METHODS

A cohort including all patients <30 years old diagnosed with type 1 diabetes in Finland in 1965-2011 was followed until start of renal replacement therapy, death, or end of follow-up at the end of 2013. Altogether, 29,906 patients were included. The main outcome was cumulative risk of ESRD, accounting for death as a competing risk.

RESULTS

The patients were followed up for a median of 20 years. During 616,403 patient-years, 1,543 ESRD cases and 4,185 deaths were recorded. The cumulative risk of ESRD was 2.2% after 20 years and 7.0% after 30 years from the diabetes diagnosis. The relative risk of ESRD was 0.13 (95% CI 0.08-0.22) among patients diagnosed in 1995-2011 compared with those diagnosed in 1965-1979. Patients <5 years old at the time of diagnosis had the lowest risk of ESRD after diagnosis. With the cumulative risk of ESRD estimated from time of birth, the patients aged 5-9 years at diabetes diagnosis were at highest risk.

CONCLUSIONS

The cumulative risk of ESRD has decreased markedly during the past five decades. This highlights the importance of modern treatment of diabetes and diabetic nephropathy.

Cumulative Kidney Complication Risk by 50 Years of Type 1 Diabetes: The Effects of Sex, Age, and Calendar Year at Onset

OBJECTIVE

A common belief is that only a minority of patients with type 1 diabetes (T1D) develop advanced kidney disease and that incidence is higher among men and lower in those diagnosed at a younger age. However, because few patients with T1D survived to older ages until recently, long-term risks have been unclear.

RESEARCH DESIGN AND METHODS

We examined the 50-year cumulative kidney complication risk in a childhood-onset T1D cohort diagnosed during 1950-80 (n = 932; mean baseline age 29 years, duration 19 years). Participants comprised 144 who died prior to baseline, 130 followed with periodic surveys, and 658 followed with biennial surveys and a maximum of nine examinations for 25 years. Micro- and macroalbuminuria were defined as an albumin excretion rate of 20-199 and ≥200 μg/min, respectively, and end-stage renal disease (ESRD) was defined as dialysis or kidney transplantation. Cumulative incidence was estimated at 10-year intervals between 20 and 50 years^, duration and compared by calendar year of diabetes onset.

RESULTS

By 50 years^, T1D duration, ESRD affected 60% of the cohort; macroalbuminuria, 72%; and microalbuminuria, 88%. Little evidence existed for declines in cumulative incidence in recent cohorts, except for ESRD (microalbuminuria 3% increase, macroalbuminuria no change; ESRD 45% decrease by 40 years of T1D duration). Onset before age 6 years was associated with the lowest risk; incidence generally did not differ by sex.

CONCLUSIONS

Some degree of kidney disease in T1D is virtually universal at long durations and not declining, which has major implications for formulating health care and research strategies. ESRD has declined, but continues to affect >25% of the population by 40 years^, duration.

Progress in Defining the Genetic Basis of Diabetic Complications

PURPOSE OF REVIEW

Diabetic complications affecting the kidneys, retina, nerves, and the cardiovasculature are the major causes of morbidity and mortality in diabetes. This paper aims to review the current understanding of the genetic basis of these complications, based on recent findings especially from genome-wide association studies.

RECENT FINDINGS

Variants in or near AFF3, RGMA-MCTP2, SP3-CDCA7, GLRA3, CNKSR3, and UMOD have reached genome-wide significance (p value <5 × 10^-8) for association with diabetic kidney disease, and recently, GRB2 was reported to be associated at genome-wide significance with diabetic retinopathy. While some loci affecting cardiovascular disease in the general population have been replicated in diabetes, GLUL affects the risk of cardiovascular disease specifically in diabetic subjects. Genetic findings are emerging for diabetic complications, although the studies remain relatively small compared to those for type 1 and type 2 diabetes. In addition to pinpointing specific loci, the studies also reveal biological information on correlated traits and pathways.

Sex differences in micro- and macro-vascular complications of diabetes mellitus

Vascular complications are a leading cause of morbidity and mortality in both men and women with type 1 (T1DM) or type 2 (T2DM) diabetes mellitus, however the prevalence, progression and pathophysiology of both microvascular (nephropathy, neuropathy and retinopathy) and macrovascular [coronary heart disease (CHD), myocardial infarction, peripheral arterial disease (PAD) and stroke] disease are different in the two sexes. In general, men appear to be at a higher risk for diabetic microvascular complications, while the consequences of macrovascular complications may be greater in women. Interestingly, in the absence of diabetes, women have a far lower risk of either micro- or macro-vascular disease compared with men for much of their lifespan. Thus, the presence of diabetes confers greater risk for vascular complications in women compared with men and some of the potential reasons, including contribution of sex hormones and sex-specific risk factors are discussed in this review. There is a growing body of evidence that sex hormones play an important role in the regulation of cardiovascular function. While estrogens are generally considered to be cardioprotective and androgens detrimental to cardiovascular health, recent findings challenge these assumptions and demonstrate diversity and complexity of sex hormone action on target tissues, especially in the setting of diabetes. While some progress has been made toward understanding the underlying mechanisms of sex differences in the pathophysiology of diabetic vascular complications, many questions and controversies remain. Future research leading to understanding of these mechanisms may contribute to personalized- and sex-specific treatment for diabetic micro- and macro-vascular disease.

Incidence and Risk Factors for Developing Diabetic Retinopathy among Youths with Type 1 or Type 2 Diabetes throughout the United States

PURPOSE

Despite the increasing prevalence of type 2 diabetes mellitus (T2DM) among children and adolescents, little is known about their risk of developing diabetic retinopathy (DR). We sought to identify risk factors for DR in youths with diabetes mellitus, to compare DR rates for youths with type 1 diabetes mellitus (T1DM) and those with T2DM, and to assess whether adherence to DR screening guidelines promoted by the American Academy of Ophthalmology, American Academy of Pediatrics, and American Diabetes Association adequately capture youths with DR.

DESIGN

Retrospective observational longitudinal cohort study.

PARTICIPANTS

Youths aged ≤21 years with newly diagnosed T1DM or T2DM who were enrolled in a large US managed-care network.

METHODS

In this study of youths aged ≤21 years with newly diagnosed T1DM or T2DM who were under ophthalmic surveillance, we identified the incidence and timing of DR onset. Kaplan-Meier survival curves assessed the timing of initial diagnosis of DR for participants. Multivariable Cox proportional hazard regression modeling identified factors associated with the hazard of developing DR. Model predictors were age and calendar year at initial diabetes mellitus diagnosis, sex, race/ethnicity, net worth, and glycated hemoglobin A1c fraction (HbA1c).

MAIN OUTCOME MEASURES

Hazard ratios (HRs) with 95% confidence intervals (CIs) for developing DR.

RESULTS

Among the 2240 youths with T1DM and 1768 youths with T2DM, 20.1% and 7.2% developed DR over a median follow-up time of 3.2 and 3.1 years, respectively. Survival curves demonstrated that youths with T1DM developed DR faster than youths with T2DM (P < 0.0001). For every 1-point increase in HbA1c, the hazard for DR increased by 20% (HR = 1.20; 95% CI 1.06-1.35) and 30% (HR = 1.30; 95% CI 1.08-1.56) among youths with T1DM and T2DM, respectively. Current guidelines suggest that ophthalmic screening begin 3 to 5 years after initial diabetes mellitus diagnosis, at which point in our study, >18% of youths with T1DM had already received ≥1 DR diagnosis.

CONCLUSIONS

Youths with T1DM or T2DM exhibit a considerable risk for DR and should undergo regular screenings by eye-care professionals to ensure timely DR diagnosis and limit progression to vision-threatening disease.

[Sex- and gender-aspects in regard to clinical practice recommendations for pre-diabetes and diabetes]

Metabolic diseases dramatically affect life of men and women from infancy up to old age and are a major challenge for clinicians. Health professionals are confronted with different needs of women and men. This article aims at an increase of gender awareness and the implementation of current knowledge of gender medicine in daily clinical practice with regard to pre-diabetes and diabetes. Sex and gender affect screening and diagnosis of metabolic diseases as well as treatment strategies and outcome. Impaired glucose and lipid metabolism, regulation of energy balance and body fat distribution are related to steroid hormones and therefore impose their influence on cardiovascular health in both men and women. Furthermore, education, income and psychosocial factors relate to development of obesity and diabetes differently in men and women. Males appear to be at greater risk of diabetes at younger age and at lower BMI compared to women, but women feature a dramatic increase of their cardiometabolic risk after menopause. The estimated future years of life lost owing to diabetes is somewhat higher in women than men, with higher increase of vascular death in women, but higher increase of cancer death in men. In women pre-diabetes or diabetes are more distinctly associated with a higher number of vascular risk factors, such as inflammatory parameters, unfavourable changes of coagulation and blood pressure. Pre-diabetic and diabetic women are at much higher relative risk for vascular disease. Women are more often obese and less physically active, but may even have greater benefit from increased physical activity than males. Whereas men predominantly feature impaired fasting glucose, women often show impaired glucose tolerance. A history of gestational diabetes or the presence of a PCOS or increased androgen levels in women, on the other hand the presence of erectile dysfunction (ED) or decreased testosterone levels in men are sex specific risk factors for diabetes development. ED is a common feature of obese men with the Metabolic Syndrome and an important predictor of cardiovascular disease. Diabetic women also feature sexual dysfunctions much more frequently than non-diabetic women which should be addressed in clinical care. Several studies showed that diabetic women reach their targets of metabolic control (HbA1c), blood pressure and LDL-cholesterol less often than their male counterparts, although the reasons for worse treatment outcome in diabetic females are not clear. Furthermore, sex differences in action, pharmacokinetics, and side effects of pharmacological therapy have to be taken into account.

The Genetic Landscape of Renal Complications in Type 1 Diabetes

Diabetes is the leading cause of ESRD. Despite evidence for a substantial heritability of diabetic kidney disease, efforts to identify genetic susceptibility variants have had limited success. We extended previous efforts in three dimensions, examining a more comprehensive set of genetic variants in larger numbers of subjects with type 1 diabetes characterized for a wider range of cross-sectional diabetic kidney disease phenotypes. In 2843 subjects, we estimated that the heritability of diabetic kidney disease was 35% (P=6.4×10^-3). Genome-wide association analysis and replication in 12,540 individuals identified no single variants reaching stringent levels of significance and, despite excellent power, provided little independent confirmation of previously published associated variants. Whole-exome sequencing in 997 subjects failed to identify any large-effect coding alleles of lower frequency influencing the risk of diabetic kidney disease. However, sets of alleles increasing body mass index (P=2.2×10^-5) and the risk of type 2 diabetes (P=6.1×10^-4) associated with the risk of diabetic kidney disease. We also found genome-wide genetic correlation between diabetic kidney disease and failure at smoking cessation (P=1.1×10^-4). Pathway analysis implicated ascorbate and aldarate metabolism (P=9.0×10^-6), and pentose and glucuronate interconversions (P=3.0×10^-6) in pathogenesis of diabetic kidney disease. These data provide further evidence for the role of genetic factors influencing diabetic kidney disease in those with type 1 diabetes and highlight some key pathways that may be responsible. Altogether these results reveal important biology behind the major cause of kidney disease.

Incidence and Risk Factors Involved in the Development of Nephropathy in Patients with Type 1 Diabetes Mellitus: Follow Up Since Onset

OBJECTIVES

Estimation of the incidence of nephropathy as well as potential risk factors involved in its onset in a cohort of patients with type 1 diabetes who were followed from diagnosis.

METHODS

We studied 716 patients, who were followed for a mean (standard deviation [SD]) of 10.1 (SD: 5.3) years. We analyzed the influence of demographic characteristics and levels of glycated hemoglobin (A1C), lipids and blood pressure during the course of the disease by univariate and multivariate survival methods.

RESULTS

The cumulative incidence of nephropathy was 2.6%, 6.3% and 11.9% at 5, 10 and 15 years of evolution, respectively. The factors associated with increased risk for nephropathy were systolic blood pressure and A1C levels. An increment of 10 mm Hg in systolic blood pressure increases the risk by 36%, and an increment of 1% in A1C levels raises the risk by 13% at 5 years since onset and 68% at 10 years, and it doubles the risk at 15 years. Women have higher risk than men (hazard ratio 1.79; p=0.024).

CONCLUSIONS

Our study suggests that female gender and high levels of A1C and systolic blood pressure throughout the course of the disease are the main factors associated with an increased risk for development of nephropathy in patients with type 1 diabetes mellitus.

Age at menarche and the risk of diabetic microvascular complications in patients with type 1 diabetes

AIMS/HYPOTHESIS

The aim of this study was to evaluate the relationship among age at onset of diabetes, age at onset of menarche and risk of diabetic nephropathy and laser-treated retinopathy in type 1 diabetes.

METHODS

Data related to age at menarche were collected through questionnaires and were available for 1,304 women who participated in the Finnish Diabetic Nephropathy Study (FinnDiane). A possible association between age at menarche and diabetic nephropathy and retinopathy was investigated.

RESULTS

There was an inverse relationship between the age at onset of diabetes and age at menarche: the younger the age at onset of diabetes, the higher the age at menarche (p < 0.0001). A non-linear relationship between the age of menarche and risk of diabetic microvascular complications was found in patients with diabetes onset before menarche, but there was no such association in patients with diabetes onset after menarche. Women with delayed menarche (> mean age + 2 years) had a 2.30 (95% CI 1.27, 4.17; p < 0.006) times higher risk of nephropathy compared with the women who underwent menarche at the mean age ± 2 years. Delayed menarche also increased the risk of retinopathy (OR 2.34 [95% CI 1.36, 4.01]). After excluding patients with nephropathy, the OR for retinopathy was 2.11 (95% CI 1.15, 3.90). Earlier menarche (< mean age - 2 years) did not have any effect on this risk.

CONCLUSIONS/INTERPRETATION

Delayed menarche was associated with an increased risk of diabetic nephropathy and retinopathy, whereas early menarche was not. Delayed menarche may be used as a new tool to identify women at risk of diabetic microvascular complications.

Influence of Age at Diagnosis and Time-Dependent Risk Factors on the Development of Diabetic Retinopathy in Patients with Type 1 Diabetes

Aim. To determine the influence of age at onset of type 1 diabetes and of traditional vascular risk factors on the development of diabetic retinopathy, in a cohort of patients who have been followed up after onset. Methods. Observational, retrospective study. The cohort consists of 989 patients who were followed up after diagnosis for a mean of 10.1 (SD: 6.8) years. The influence of age at diagnosis, glycemic control, duration of diabetes, sex, blood pressure, lipids, BMI, and smoking is analyzed using Cox univariate and multivariate models with fixed and time-dependent variables. Results. 135 patients (13.7%) developed diabetic retinopathy. The cumulative incidence was 0.7, 5.9, and 21.8% at 5-, 10-, and 15-year follow-up, respectively. Compared to the group with onset at age <10 years, the risk of retinopathy increased 2.5-, 3-, 3.3-, and 3.7-fold in the groups with onset at 10-14, 15-29, 30-44, and >44 years, respectively. During follow-up we also observed an association between diabetic retinopathy and HbA1c levels, HDL-cholesterol, and diastolic blood pressure. Conclusion. The rate of diabetic retinopathy is higher in patients who were older at type 1 diabetes diagnosis. In addition, we confirmed the influence of glycemic control, HDL-cholesterol, and diastolic blood pressure on the occurrence of retinopathy.

Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss

Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.

Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss

Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.

Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications over 15-year follow-up: the Diabetes Prevention Program Outcomes Study

BACKGROUND

Effective prevention is needed to combat the worldwide epidemic of type 2 diabetes. We investigated the long-term extent of beneficial effects of lifestyle intervention and metformin on diabetes prevention, originally shown during the 3-year Diabetes Prevention Program (DPP), and assessed whether these interventions reduced diabetes-associated microvascular complications.

METHODS

The DPP (1996-2001) was a randomised trial comparing an intensive lifestyle intervention or masked metformin with placebo in a cohort selected to be at very high risk of developing diabetes. All participants were offered lifestyle training at the end of the DPP. 2776 (88%) of the surviving DPP cohort were followed up in the DPP Outcomes Study (DPPOS, Sept 1, 2002, to Jan 2, 2014) and analysed by intention to treat on the basis of their original DPP assignment. During DPPOS, the original lifestyle intervention group was offered lifestyle reinforcement semi-annually and the metformin group received unmasked metformin. The primary outcomes were the development of diabetes and the prevalence of microvascular disease. For the assessment of microvascular disease, we used an aggregate microvascular outcome, composed of nephropathy, retinopathy, and neuropathy.

FINDINGS

During a mean follow-up of 15 years, diabetes incidence was reduced by 27% in the lifestyle intervention group (hazard ratio 0·73, 95% CI 0·65-0·83; p<0·0001) and by 18% in the metformin group (0·82, 0·72-0·93; p=0·001), compared with the placebo group, with declining between-group differences over time. At year 15, the cumulative incidences of diabetes were 55% in the lifestyle group, 56% in the metformin group, and 62% in the placebo group. The prevalences at the end of the study of the aggregate microvascular outcome were not significantly different between the treatment groups in the total cohort (placebo 12·4%, 95% CI 11·1-13·8; metformin 13·0%, 11·7-14·5; lifestyle intervention 11·3%, 10·1-12·7). However, in women (n=1887) the lifestyle intervention was associated with a lower prevalence (8·7%, 95% CI 7·4-10·2) than in the placebo (11·0%, 9·6-12·6) and metformin (11·2%, 9·7-12·9) groups, with reductions in the lifestyle intervention group of 21% (p=0·03) compared with placebo and 22% (p=0·02) compared with metformin. Compared with participants who developed diabetes, those who did not develop diabetes had a 28% lower prevalence of microvascular complications (relative risk 0·72, 95% CI 0·63-0·83; p<0·0001).

INTERPRETATION

Lifestyle intervention or metformin significantly reduced diabetes development over 15 years. There were no overall differences in the aggregate microvascular outcome between treatment groups; however, those who did not develop diabetes had a lower prevalence of microvascular complications than those who did develop diabetes. This result supports the importance of diabetes prevention.

FUNDING

National Institute of Diabetes and Digestive and Kidney Diseases.

Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss

Diabetic retinopathy (DR) is a leading cause of vision-loss globally. Of an estimated 285 million people with diabetes mellitus worldwide, approximately one third have signs of DR and of these, a further one third of DR is vision-threatening DR, including diabetic macular edema (DME). The identification of established modifiable risk factors for DR such as hyperglycemia and hypertension has provided the basis for risk factor control in preventing onset and progression of DR. Additional research investigating novel risk factors has improved our understanding of multiple biological pathways involved in the pathogenesis of DR and DME, especially those involved in inflammation and oxidative stress. Variations in DR prevalence between populations have also sparked interest in genetic studies to identify loci associated with disease susceptibility. In this review, major trends in the prevalence, incidence, progression and regression of DR and DME are explored, and gaps in literature identified. Established and novel risk factors are also extensively reviewed with a focus on landmark studies and updates from the recent literature.

Genetics of diabetic nephropathy: a long road of discovery

The global prevalence of diabetic nephropathy is rising in parallel with the increasing incidence of diabetes in most countries. Unfortunately, up to 40 % of persons diagnosed with diabetes may develop kidney complications. Diabetic nephropathy is associated with substantially increased risks of cardiovascular disease and premature mortality. An inherited susceptibility to diabetic nephropathy exists, and progress is being made unravelling the genetic basis for nephropathy thanks to international research collaborations, shared biological resources and new analytical approaches. Multiple epidemiological studies have highlighted the clinical heterogeneity of nephropathy and the need for better phenotyping to help define important subgroups for analysis and increase the power of genetic studies. Collaborative genome-wide association studies for nephropathy have reported unique genes, highlighted novel biological pathways and suggested new disease mechanisms, but progress towards clinically relevant risk prediction models for diabetic nephropathy has been slow. This review summarises the current status, recent developments and ongoing challenges elucidating the genetics of diabetic nephropathy.

Genetics and Epigenetics of Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy (DN) is the most common cause of end-stage renal disease (ESRD) in the USA and worldwide, contributing to significant morbidity and mortality in diabetic patients. A genetic factor for the development of DN is strongly implicated, as only one third of diabetic patients eventually develop kidney disease. Growing evidence also supports an important role of epigenetic modifications in DN.

SUMMARY

Multiple studies have been performed to identify risk genes and loci associated with DN. So far, only several genes and loci have been identified, none of which showed a strong association with DN. Therefore, a better study design with a larger sample size to identify rare variants and a clinically defined patient population to identify genes and loci associated with progressive DN are still needed. In addition to genetic factors, epigenetic modifications, such as DNA methylation, histone modifications and microRNAs, also play a major role in the pathogenesis of DN through a second layer of gene regulation. Although a major progress has been made in this field, epigenetic studies in DN are still in the early phase and have been limited mostly due to the heterogeneity of kidney tissue samples with multiple cells. However, rapid development of high-throughput genome-wide techniques will help us to better identify genetic variants and epigenetic changes in DN.

KEY MESSAGE

Understanding of genetic and epigenetic changes in DN is needed for the development of new biomarkers and better drug targets against DN. Summarized in this review are important recent findings on genetic and epigenetic studies in the field of DN.

Prevalence of diabetic retinopathy in young adults with type 1 diabetes since childhood: the Oulu cohort study of diabetic retinopathy

PURPOSE

To evaluate the prevalence and stage of diabetic retinopathy (DR) in a population-based cohort of young Finnish adults who have had type 1 diabetes (T1D) since childhood.

MATERIAL AND METHODS

The cohort includes all 5- to 16-year-old patients with T1D who lived in the Northern Ostrobothnia Hospital District of Finland, in 1989 (n = 216). DR was evaluated from fundus photographs taken in 1989-1990 and again in 2007. The patients were 7 ± 4 years age (range 0-15 years) at the time of diagnosis of T1D, and the average duration of diabetes at the re-evaluation was 23 ± 4 years (range 17-32 years).

RESULTS

The prevalence of DR was analysed in 172 patients (80% of the original cohort) at 22-35 years. Proliferative DR (PDR) was observed in 35% (60/172) and non-proliferative DR in 59% (101/172), with no signs of DR being present in the remaining 6% (11/172) of the subjects. The prevalence of DR did not differ by gender (p = 0.356).

CONCLUSIONS

After the 18-year follow-up, a high prevalence of DR and PDR (94% and 35%, respectively) was found in patients who have had T1D since childhood, with no difference between the genders.

Association of glycemic status with impaired lung function among recipients of a health screening program: a cross-sectional study in Japanese adults

Background

The dose-response relationship between glycemic status and lung function has not been thoroughly investigated. We hypothesized that there are continuous and inverse associations between glycemic measures and lung function tests and examined the hypothesis in Japanese adults.

Methods

We cross-sectionally investigated associations of hemoglobin A1c (HbA1c) and fasting plasma glucose (FPG) with forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) in 3161 adults who participated in a health screening from 2008 to 2011. The study participants included both diabetic and non-diabetic adults. Multiple linear regression analyses were performed to examine the associations.

Results

Inverse associations were observed in both sexes, which were attenuated in women after adjustment for multiple variables. A 1% absolute increase in HbA1c was associated with a −52-mL (95% confidence interval [CI] −111 to 8 mL) difference in FVC and a −25-mL (95% CI −75 to 25 mL) difference in FEV1 in women, and a −128-mL (95% CI −163 to −94 mL) difference in FVC and a −73-mL (95% CI −101 to −44 mL) difference in FEV1 in men. A 10-mg/dL increase in FPG was associated with a −11-mL (95% CI −29 to 8 mL) difference in FVC and a −8-mL (95% CI −24 to 7 mL) difference in FEV1 in women, and a −32-mL (95% CI −44 to −21 mL) difference in FVC and a −19-mL (95% CI −28 to −9 mL) difference in FEV1 in men.

Conclusions

Inverse associations between glycemic measures and lung function were observed. Men seem more susceptible to the alteration in FVC and FEV1 than women.

Epidemiology and risk factors for diabetic kidney disease

Prevalence rates of diabetic kidney disease (DKD) are increasing in parallel with the incidence rates of diabetes mellitus. DKD has already become a significant health problem worldwide. Without radical improvements in prevention and treatment, DKD prevalence will continue to climb. The pathogenesis of DKD is complex and multifactorial, with genetic and environmental factors involved. Several nonmodifiable risk factors contribute to DKD, including genetics, sex, age, age at onset, and duration of diabetes. However, there are also several modifiable risk factors that have a strong effect on the risk of DKD. Traditional modifiable factors include glycemic control, blood pressure, lipids, and smoking. Other recently discovered modifiable risk factors include chronic low-grade inflammation, advanced glycation end products, and lack of physical activity. Efficient management of these modifiable risk factors may improve the prognosis of diabetic patients at risk of DKD.

Tubulointerstitial disease in diabetic nephropathy

Diabetes mellitus is the major cause of end stage renal disease (ESRD). We cannot predict which patient will be affected. ESRD patients suffer an extremely high mortality rate, due to a very high incidence of cardiovascular disease. Several randomized, prospective studies have been conducted to quantify the impact of strict glycemic control on morbidity and mortality, and have consistently demonstrated an association between strict glycemic control and a reduction in ESRD. Within the past 20 years, despite the implementation of treatments that were presumed to be renoprotective, diabetes mellitus has continued to rank as the leading cause of ESRD, which clearly indicates that we are still far from understanding the mechanisms involved in the initiation of ESRD. Progressive albuminuria has been considered as the sine qua non of diabetic nephropathy, but we know now that progression to diabetic nephropathy may well happen in the absence of initial microalbuminuria. The search for new biomarkers of early kidney damage has received increasing interest, since early identification of the pathways leading to kidney damage may allow us to adopt measures to prevent the development of ESRD. Most of these biomarkers are deeply influenced by environment, genetics, sex differences, and so on, making it extremely difficult to identify the ideal biomarker to target. At present, there are no new drugs that come close to providing the solutions we desire for our patients (ie, reducing complications). Even when used in combination with standard care, renal complications are, at best, only modestly reduced, at the considerable expense of additional pill burden and exposure to serious off-target effects. In this review, some of the hypothesized mechanisms of this heterogeneous disease will be considered, with particular attention to the tubule–interstitial compartment.

Renal replacement therapy due to type 1 diabetes; time trends during 1995-2010--a Swedish population based register study

BACKGROUND

End stage renal disease (ESRD), is the most severe complication of diabetes mellitus. This population-based study analysed time trends for start of renal replacement therapy (RRT) due to type 1 diabetes compared to type 2 diabetes and other diagnoses.

MATERIAL AND METHODS

We used data on patients who were registered 1995-2010 in the Swedish Renal Registry, a nationwide register covering 95 % of all patients with uraemia. The patients were analysed according to their original kidney disease. The incidence was analysed by calendar year, age at start of RRT and gender.

RESULTS

Of 17389 patients who were registered, 1833 had type 1 diabetes; 65% were men. The mean age at onset of RRT for patients with type 1 diabetes was 52.8 years which increased by more than 3 years over the studied period. The number of patients in need of RRT due to type 1 diabetes decreased, while RRT due to type 2 diabetes increased during the period studied.

CONCLUSIONS

The overall incidence of RRT in Sweden is rather constant over the years but the need for RRT in type 1 diabetes patients decreased and patients with type 1 diabetes tend to become older at onset of RRT.

Impact of sex and age at onset of diabetes on mortality from ischemic heart disease in patients with type 1 diabetes

OBJECTIVE To study whether ischemic heart disease (IHD) mortality among patients with type 1 diabetes (T1D) depends on the age at onset of diabetes and whether this effect is sex specific. RESEARCH DESIGN AND METHODS The study examined long-term IHD-specific mortality in a Finnish population-based cohort of patients with early-onset (0-14 years) and late-onset (15-29 years) T1D (n = 17,306). RESULTS During 433,782 person-years of follow-up, 478 deaths from IHD were observed. Within the early-onset cohort, the average crude mortality rate in women was 33.3% lower than in men, whereas in the late-onset cohort, mortality was only one-half that in men. In contrast, the standardized mortality ratio (SMR) was higher in women than in men (21.6 [95% CI 17.2-27.0] vs. 5.8 [5.1-6.6]). The difference in SMR between sexes was more striking in the early-onset cohort (women 52.8 [36.3-74.5], men 12.1 [9.2-15.8]). The SMR was also greater in women in the late-onset cohort (15.8 [11.8-20.7]) compared with men (5.0 [4.3-5.8]). The relative risk of dying from IHD was greatest in women aged <40 years and 40-60 years in the early- and late-onset cohorts, respectively. CONCLUSIONS The risk of mortality from IHD is exceptionally high in women with early-onset T1D compared with women in the background population. These observations underscore the importance of identifying risk factors early in women and delivering more-aggressive treatment after diagnosis.

Chromosome 2q31.1 associates with ESRD in women with type 1 diabetes

Sex and genetic variation influence the risk of developing diabetic nephropathy and ESRD in patients with type 1 diabetes. We performed a genome-wide association study in a cohort of 3652 patients from the Finnish Diabetic Nephropathy (FinnDiane) Study with type 1 diabetes to determine whether sex-specific genetic risk factors for ESRD exist. A common variant, rs4972593 on chromosome 2q31.1, was associated with ESRD in women (P<5×10(-8)) but not in men (P=0.77). This association was replicated in the meta-analysis of three independent type 1 diabetes cohorts (P=0.02) and remained significant for women (P<5×10(-8); odds ratio, 1.81 [95% confidence interval, 1.47 to 2.24]) upon combined meta-analysis of the discovery and replication cohorts. rs4972593 is located between the genes that code for the Sp3 transcription factor, which interacts directly with estrogen receptor α and regulates the expression of genes linked to glomerular function and the pathogenesis of nephropathy, and the CDCA7 transcription factor, which regulates cell proliferation. Further examination revealed potential transcription factor-binding sites within rs4972593 and predicted eight estrogen-responsive elements within 5 kb of this locus. Moreover, we found sex-specific differences in the glomerular expression levels of SP3 (P=0.004). Overall, these results suggest that rs4972593 is a sex-specific genetic variant associated with ESRD in patients with type 1 diabetes and may underlie the sex-specific protection against ESRD.

Microvascular complications in adolescents with type 1 diabetes mellitus

OBJECTIVE

Screening of complications is an important part of diabetes care. The aim of this study was to investigate diabetic complications and related risk factors in adolescents with type 1 diabetes mellitus (T1DM).

METHODS

This cross-sectional study was conducted on type 1 diabetics who were over 11 years of age or had a diabetes duration of 2 years and included 155 adolescents with T1DM (67 male, 88 female). The mean age of the patients was 14.4±2.1 years. Mean diabetes duration was 6.3±2.9 years. The patients were screened for diabetic nephropathy, retinopathy and peripheral neuropathy.

RESULTS

Mean glycosylated hemoglobin (HbA1c) level of the study group was 8.4%. The frequency of microalbuminuria and peripheral neuropathy were 16.1% and 0.6%, respectively. None of the patients had diabetic retinopathy. Dyslipidemia and hypertension rates were 30.3% and 12.3%, respectively. Risk factors associated with microalbuminuria were hypertension, higher HbA1c levels, longer diabetes duration and dyslipidemia.

CONCLUSION

Early diagnosis and treatment of hypertension and dyslipidemia as well as achieving a better metabolic control are important in prevention or postponement of complications in patients with T1DM. Yearly screening for diabetic nephropathy should be started 2 years after the onset of the diabetes.

Gender and the prevalence and progression of renal disease

In most experimental models of CKD, male animals progress more rapidly than females. Modulation of the hormonal milieu can replicate the effects of gender on the course of kidney disease. These observations suggest that sex hormones per se may be important determinants of the greater susceptibility of males to progressive kidney injury. The predominance of data in humans suggests that the course of nondiabetic kidney disease is more aggressive in men than women. Male gender is arguably also a risk factor for progression of diabetic nephropathy. Sex hormones directly or indirectly affect many cellular processes by modulating the synthesis of various cytokines, growth factors, and vasoactive agents. In particular, estrogen acts in a receptor-dependent mechanism to regulate genes involved in extracellular matrix metabolism. Estrogen has profound effects on transforming growth factor-β signal transduction and on the renin-angiotensin system. These effects may contribute to alterations in kidney hemodynamics and affect kidney disease progression. Selective estrogen receptor modulators, agents that mimic many of the beneficial effects of estrogen without reproducing estrogen's deleterious effects on reproductive tissue, ameliorate the course of kidney disease in animal models and in postmenopausal women.

[Sex- and gender-aspects in regard to clinical practice recommendations for pre-diabetes and diabetes]

Metabolic diseases dramatically affect life of men and women from infancy up to old age and are a major challenge for clinicians. Health professionals are confronted with different needs of women and men. This article aims at an increase of gender awareness and the implementation of current knowledge of gender medicine in daily clinical practice with regard to pre-diabetes and diabetes. Sex and gender affect screening and diagnosis of metabolic diseases as well as treatment strategies and outcome. Impaired glucose and lipid metabolism, regulation of energy balance and body fat distribution are related to steroid hormones and therefore impose their influence on cardiovascular health in both men and women. Furthermore, education, income and psychosocial factors relate to development of obesity and diabetes differently in men and women. Males appear to be at greater risk of diabetes at younger age and at lower BMI compared to women, but women feature a dramatic increase of their cardiometabolic risk after menopause. The estimated future years of life lost owing to diabetes is somewhat higher in women than men, with higher increase of vascular death in women, but higher increase of cancer death in men. In women pre-diabetes or diabetes are more distinctly associated with a higher number of vascular risk factors, such as inflammatory parameters, unfavourable changes of coagulation and blood pressure. Pre-diabetic and diabetic women are at much higher risk for vascular disease (3-6 times compared to non-diabetic women) than diabetic men (2-3 times compared to healthy males). Women are more often obese and less physically active, but may even have greater benefit from increased physical activity than males. Whereas men predominantly feature impaired fasting glucose, women often show impaired glucose tolerance. A history of gestational diabetes or the presence of a PCOS or increased androgen levels in women, on the other hand the presence of erectile dysfunction (ED) or decreased testosterone levels in men are sex specific risk factors for diabetes development. ED is a common feature of obese men with the Metabolic Syndrome and an important predictor of cardiovascular disease. Several studies showed that diabetic women reach their targets of metabolic control (HbA1c), blood pressure and LDL-cholesterol less often than their male counterparts, although the reasons for worse treatment outcome in diabetic females are not clear. Furthermore, sex differences in action, pharmacokinetics, and side effects of pharmacological therapy have to be taken into account.

Sex-specific-differences in cardiometabolic risk in type 1 diabetes: a cross-sectional study

Background

Little is known about the impact of sex-specific differences in the management of type 1 diabetes (T1DM).

Thus, we evaluated the influence of gender on risk factors, complications, clinical care and adherence in patients with T1DM.

Methods

In a cross-sectional study, sex-specific disparities in glycaemic control, cardiovascular risk factors, diabetic complications, concomitant medication use and adherence to treatment recommendations were evaluated in 225 consecutive patients (45.3% women) who were comparable with respect to age, diabetes duration, and body mass index.

Results

Although women with T1DM had a higher total cholesterol than men, triglycerides were higher in obese men and males with HbA1c>7% than in their female counterparts. No sex differences were observed in glycaemic control and in micro- or macrovascular complications. However, the subgroup analysis showed that nephropathy was more common in obese men, hyperlipidaemic women and all hypertensive patients, whereas peripheral neuropathy was more common in hyperlipidaemic women. Retinopathy was found more frequently in women with HbA1c>7%, obese men and in both sexes with a long duration of diabetes. The multivariate analysis revealed that microvascular complications were associated with the duration of disease and BMI in both sexes and with hyperlipidaemia in males. The overall adherence to interventions according to the guidelines was higher in men than in women. This adherence was concerned particularly with co-medication in patients diagnosed with hypertension, aspirin prescription in elderly patients and the achievement of target lipid levels following the prescription of statins.

Conclusions

Our data showed sex differences in lipids and overweight in patients with T1DM. Although glycaemic control and the frequency of diabetic complications were comparable between the sexes, the overall adherence to guidelines, particularly with respect to the prescription of statins and aspirin, was lower in women than in men.

Renal lesions predict progression of diabetic nephropathy in type 1 diabetes

Whether early glomerular, tubulointerstitial, vascular, and global glomerulosclerotic lesions can predict progression of diabetic nephropathy is not well defined. Here, we sought to determine whether renal structural parameters predict the development of proteinuria or ESRD after long-term follow-up. We measured several renal structures in kidney biopsies from 94 normoalbuminuric patients with longstanding type 1 diabetes using unbiased morphometric methods. Greater width of the glomerular basement membrane and higher levels of glycated hemoglobin were independent predictors of progression to diabetic nephropathy in this normoalbuminuric cohort. Moreover, none of these patients with type 1 diabetes who had glomerular basement membrane widths within the normal range developed proteinuria and/or ESRD. In conclusion, careful quantitative assessment of kidney biopsies in normoalbuminuric patients with type 1 diabetes adds substantially to the prediction of progression to clinical diabetic nephropathy.

Sugar, sex, and TGF-β in diabetic nephropathy

TGF-β is well known to play a critical role in diabetic kidney disease, and ongoing clinical studies are testing the potential therapeutic promise of inhibiting TGF-β production and action. An aspect of TGF-β action that has not received much attention is its potential role in explaining sex-related proclivity for kidney disease. In this review, we discuss recent studies linking TGF-β signaling to sex-related effects in diabetic kidney disease and suggest targets for future studies.