Epidemiology of diabetic kidney disease in adult patients with type 1 diabetes in Italy: The AMD-Annals initiative

Causality between serum uric acid and diabetic microvascular complications - a mendelian randomization study

BACKGROUND

The aim of this study was to investigate whether a causal relationship exists between serum uric acid (SUA) and diabetic microvascular complications using a two-sample Mendelian randomization (MR) method.

METHODS

We used the MR approach, utilizing genome-wide association study (GWAS) summary statistics, to estimate the causal effect of SUA on diabetic microvascular complications in European individuals. The summary statistical data of SUA were obtained from the open database (IEU OPEN GWAS PROJECT) (p < 5 × 10- 8), and data on diabetic microvascular complications (diabetic nephropathy, diabetic neuropathy, diabetic retinopathy) were obtained from the FinnGen consortium. F-statistics were calculated to assess the correlation between instrumental variables (IVs) and SUA, and single nucleotide polymorphisms (SNPs) associated with confounders or outcomes were excluded by consulting the PhenoScanner database. Inverse variance weighting (IVW) was used for primary estimation, and MR‒Egger, weighted median (WM), and Mendelian randomization pleiotropy residuals sum and outliers (MR-PRESSO) were used for additional assessment. Heterogeneity was assessed using the Cochran's Q test, and polytropy was assessed using the MR‒Egger intercept.

RESULTS

MR analysis revealed a causal relationship between a genetically predicted increase in SUA and diabetic nephropathy [OR = 1.32, 95%(CI) = 1.07-1.63, p = 0.008]. The results were consistent with those after MR-PRESSO [OR = 1.30, 95%(CI) = 1.07-1.58, p = 0.008]. There was a causal relationship between type 2 diabetes mellitus (T2DM) and renal complication IVW [OR = 1.27, 95%(CI) = 1.00-1.62, p = 0.049]. These results were consistent with those after MR-PRESSO [OR = 1.27, 95%(CI) = 1.00-1.62, p = 0.050]. There was no significant causal relationship between the genetically predicted increase in SUA and diabetic retinopathy [OR 1.09, 95%(CI) = 0.94-1.26, p = 0.249] or diabetic neuropathy [OR = 1.08, 95%(CI) = 0.84-1.40, p = 0.549].

CONCLUSIONS

This MR analysis suggests a causal relationship between genetically predicted uric acid increases and diabetic microvascular complications. A significant causal relationship exists between SUA and diabetic nephropathy but not between SUA and diabetic retinopathy or diabetic neuropathy.

Effectiveness of the flash glucose monitoring system in preventing severe hypoglycemic episodes and in improving glucose metrics and quality of life in subjects with type 1 diabetes at high risk of acute diabetes complications

AIMS

To assess the effectiveness of the intermittent-scanned continuous glucose monitoring (isCGM) system in preventing severe hypoglycemic episodes and in improving glucose parameters and quality of life.

METHODS

Four hundred T1D individuals were enrolled in a prospective real-word study with an intermittently scanned continuous glucose monitoring device during the 12-months follow-up. The primary endpoint was the incidence of severe hypoglycemic events.

RESULTS

82% of subjects were naïve to the use of the device (group A) and 18% were already wearing the system (group B). The cumulative incidence of severe hypoglycemia (SH) at 12 months was 12.06 per 100 person-year (95% CI: 8.35-16.85) in group A and 10.14 (95% CI: 4.08-20.90) in group B without inter-group differences. In group A there was a significant decrease in SH at 12 months compared to 3 months period (p = 0.005). Time in glucose range significantly increased in both groups accompanied with a significant decrease in glucose variability. HbA1c showed a progressive significant time-dependent decrease in group A. The use of the device significantly improved the perceived quality of life.

CONCLUSION

This study confirmed the effectiveness of the isCGM in reducing hypoglycemic risk without glucose deterioration, with potential benefits on adverse outcomes in T1D individuals.

TRIAL REGISTRATION

ClinicalTrials.gov registration no. NCT04060732.

Social deprivation and diabetic kidney disease: A European view

There is a large body of literature demonstrating a social gradient in health and increasing evidence of an association between social deprivation and diabetes complications. Diabetic kidney disease (DKD) increases mortality in people with diabetes. Socioeconomic deprivation is increasingly recognized as a modifier of risk factors for kidney disease but also an independent risk factor itself for kidney disease. This may not be truly appreciated by clinicians and warrants further attention and exploration. In this review we explore the literature to date from Europe on the relationship between social deprivation and DKD. The majority of the studies showed at least an association with microalbuminuria, an early marker of DKD, while many showed an association with overt nephropathy. This was seen across many countries in Europe using a variety of different measures of deprivation. We reviewed and considered the mechanisms by which deprivation may lead to DKD. Health related behaviors such as smoking and suboptimal control of risk factors such as hypertension, hyperglycemia and elevated body mass index (BMI) accounts for some but not all of the association. Poorer access to healthcare, health literacy, and stress are also discussed as potential mediators of the association. Addressing deprivation is difficult but starting points include targeted interventions for people living in deprived circumstances, equitable roll out of diabetes technology, and flexible outpatient clinic arrangements including virtual and community-based care.

Association of thyroid autoantibodies and diabetic kidney disease in hospitalised patients with type 2 diabetes mellitus: a cross-sectional study from a Chinese university hospital

OBJECTIVES

To analyse and explore the association between thyroid autoantibodies and diabetic kidney disease (DKD) in patients with type 2 diabetes mellitus (T2DM).

DESIGN

A cross-sectional study.

SETTING

Patients were from the inpatient unit at The Second Endocrinology Department of Shengjing Hospital Affiliated to China Medical University (Shenyang, China) between January 2015 and September 2019.

PARTICIPANTS

A total of 150 Chinese adults with T2DM were included in the study, including 83 men and 67 women. Their age ranged between 25 and 92 years.

METHODOLOGY

They grouped by the presence of DKD, urine albumin-to-creatinine ratio (UACR), estimated glomerular filtration rate, and levels of thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb). Data on the patients' general characteristics and laboratory measurements (levels of fasting plasma glucose, glycated haemoglobin, and albumin; renal function; and thyroid function) were collected. Binary logistic regression was performed to identify risk factors for DKD.

RESULTS

The level of TPOAb, the positivity rates of TPOAb (p<0.01) and TgAb (p<0.05) were higher in patients with DKD than in those without DKD. The TPOAb level in patients with a UACR<30 mg/g creatinine was lower than that in patients with a UACR between 30 and 300 mg/g creatinine (p<0.05). The prevalence of DKD was higher in patients with a TPOAb-positive or TgAb-positive status. The result of binary logistic regression analysis showed that a TPOAb-positive status was significantly associated with DKD in patients with T2DM (OR=7.683, 95% CI 1.583 to 37.286, p<0.05).

CONCLUSIONS

TPOAb-positive status is in association with DKD in patients with T2DM. Large scale, prospective cohort studies are warranted to confirm our findings.

Causality of Diabetic Nephropathy and Age-Related Macular Degeneration: A Mendelian Randomization Study

PURPOSE

Age-related macular degeneration (AMD) currently stands as the leading cause of irreversible vision loss in the present era. The primary objective of this study was to investigate the causal relationships between diabetic nephropathy (DN), its associated risk factors, and AMD among participants of European descent.

METHODS

Genetic variants associated with DN and its risk factors, encompassing glycemic traits, lipidemic traits, systolic/diastolic blood pressure, obesity, and urate, were obtained from previously published genome-wide association studies. Summary-level statistics for AMD were acquired from the FinnGen database. Univariable and multivariable Mendelian randomization (MR) were employed to conduct this investigation.

RESULTS

Our MR analyses indicated that per 1-standard deviation (SD) increase of DN heightened the risk of overall AMD (p = 1.03 × 10-8, OR = 1.24). And these findings remained consistent when examining both dry AMD (p = 2.27 × 10-4, OR = 1.17) and wet AMD (p = 5.15 × 10-6, OR = 1.33). Additionally, there was a causal association between high-density lipoprotein-cholesterol (HDL-C) levels and an increased risk of AMD (p = 2.69 × 10-3, OR = 1.23), while triglycerides were found to mitigate the risk (p = 0.02, OR = 0.83). Notably, no significant associations were observed between other risk factors of DN and AMD.

CONCLUSIONS

These findings suggest that the impact of DN on the development of AMD may be more substantial than previously believed. Furthermore, elevated HDL-C levels appear to heighten the risk of AMD, whereas triglycerides may provide a protective effect.

Uric acid and diabetes mellitus: an update

The relationship between diabetes mellitus (DM) and high serum uric acid is complex and controversial. Many epidemiological studies have reported a positive association, whereas others have reported an inverse association or none. In the pathogenesis of DM it is the intracellular urate that is more important than the extracellular and dissociation between the two is possible. Evidence suggests that high serum uric acid induces insulin resistance and beta cell failure in animal models. Reduction of intracellular uric acid can be achieved by dietary measures such as reducing fructose and salt intake, and uric acid-lowering drugs. We suggest that in the Western diet, these elements play a crucial role in pathogenesis of DM. To determine the precise and exact interrelationship between intracellular and extracellular uric acid, well-designed studies are required. Besides this, clinical trials are needed to determine whether intracellular and extracellular urate reduction will provide benefit in prevention and treatment of DM and complications associated with it.

Physical exercise as a friend not a foe in acute kidney diseases through immune system modulation

Regular and moderate exercise is being used for therapeutic purposes in treating several diseases, including cancer, cardiovascular diseases, arthritis, and even chronic kidney diseases (CKDs). Conversely, extenuating physical exercise has long been pointed out as one of the sources of acute kidney injury (AKI) due to its severe impact on the body's physiology. AKI development is associated with increased tubular necrosis, which initiates a cascade of inflammatory responses. The latter involves cytokine production, immune cell (macrophages, lymphocytes, and neutrophils, among others) activation, and increased oxidative stress. AKI can induce prolonged fibrosis stimulation, leading to CKD development. The need for therapeutic alternative treatments for AKI is still a relevant issue. In this context arises the question as to whether moderate, not extenuating, exercise could, on some level, prevent AKI. Several studies have shown that moderate exercise can help reduce tissue damage and increase the functional recovery of the kidneys after an acute injury. In particular, the immune system can be modulated by exercise, leading to a better recovery from different pathologies. In this review, we aimed to explore the role of exercise not as a trigger of AKI, but as a modulator of the inflammatory/immune system in the prevention or recovery from AKI in different scenarios. In AKI induced by ischemia and reperfusion, sepsis, diabetes, antibiotics, or chemotherapy, regular and/or moderate exercise could modulate the immune system toward a more regulatory immune response, presenting, in general, an anti-inflammatory profile. Exercise was shown to diminish oxidative stress, inflammatory markers (caspase-3, lactate dehydrogenase, and nitric oxide), inflammatory cytokines (interleukin (IL)-1b, IL-6, IL-8, and tumor necrosis factor-α (TNF-α)), modulate lymphocytes to an immune suppressive phenotype, and decrease tumor necrosis factor-β (TGF-β), a cytokine associated with fibrosis development. Thus, it creates an AKI recovery environment with less tissue damage, hypoxia, apoptosis, or fibrosis. In conclusion, the practice of regular moderate physical exercise has an impact on the immune system, favoring a regulatory and anti-inflammatory profile that prevents the occurrence of AKI and/or assists in the recovery from AKI. Moderate exercise should be considered for patients with AKI as a complementary therapy.

Potential Medicinal Value of Rhein for Diabetic Kidney Disease

Diabetic kidney disease (DKD) is the primary cause of mortality among diabetic patients. With the increasing prevalence of diabetes, it has become a major concern around the world. The therapeutic effect of clinical use of drugs is far from expected, and therapy choices to slow the progression of DKD remain restricted. Therefore, research on new drugs and treatments for DKD has been a hot topic in the medical field. It has been found that rhein has the potential to target the pathogenesis of DKD and has a wide range of pharmacological effects on DKD, such as anti-nephritis, decreasing blood glucose, controlling blood lipids and renal protection. In recent years, the medical value of rhein in the treatment of diabetes, DKD and renal disease has gradually attracted worldwide attention, especially its potential in the treatment of DKD. Currently, DKD can only be treated with medications from a single symptom and are accompanied by adverse effects, while rhein improves DKD with a multi-pathway and multi-target approach. Therefore, this paper reviews the therapeutic effects of rhein on DKD, and proposes solutions to the limitations of rhein itself, in order to provide valuable references for the clinical application of rhein in DKD and the development of new drugs.

Broadening horizons in mechanisms, management, and treatment of diabetic kidney disease

Diabetic kidney disease (DKD) is the first cause of end-stage kidney disease in patients with diabetes and its prevalence is increasing worldwide. It encompasses histological alterations that mainly affect the glomerular filtration unit, which include thickening of the basement membrane, mesangial cell proliferation, endothelial alteration, and podocyte injury. These morphological abnormalities further result in a persistent increase of urinary albumin-to-creatinine ratio and in a reduction of the estimated glomerular filtration rate. Several molecular and cellular mechanisms have been recognized, up to date, as major players in mediating such clinical and histological features and many more are being under investigation. This review summarizes the most recent advances in understanding cell death mechanisms, intracellular signaling pathways and molecular effectors that play a role in the onset and progression of diabetic kidney damage. Some of those molecular and cellular mechanisms have been already successfully targeted in preclinical models of DKD and, in some cases, strategies have been tested in clinical trials. Finally, this report sheds light on the relevance of novel pathways that may become therapeutic targets for future applications in DKD.

Triglyceride content of lipoprotein subclasses and kidney hemodynamic function and injury in adolescents with type 1 diabetes

AIMS

Elevated triglycerides (TG) are associated with development and progression of kidney disease, and TG distributions across lipoprotein subclasses predict kidney dysfunction in adults with type 1 diabetes (T1D). Little is known regarding these relationships in youth.

METHODS

In this single center study conducted from October 2018-2019, lipid constituents from lipoprotein subclasses were quantified by targeted nuclear magnetic resonance spectroscopy. Glomerular filtration rate (GFR), renal plasma flow (RPF), afferent arteriolar resistance (RA), efferent arteriolar resistance (RE), intraglomerular pressure (PGLO), urine albumin-to-creatinine ratio (UACR), and chitinase-3-like protein 1 (YKL-40), a marker of kidney tubule injury, were assessed. Cross-sectional relationships were assessed by correlation and multivariable linear regression (adjusted for age, sex, HbA1c) models.

RESULTS

Fifty youth with T1D (age 16 ± 3 years, 50 % female, HbA1c 8.7 ± 1.3 %, T1D duration 5.7 ± 2.6 years) were included. Very-low-density lipoprotein (VLDL)-TG concentrations correlated and associated with intraglomerular hemodynamic function markers including GFR, PGLO, UACR, as did small low-density lipoprotein (LDL)-TG and small high-density lipoprotein (HDL)-TG. YKL-40 correlated with all lipoprotein subclasses.

CONCLUSION

TG within lipoprotein subclasses, particularly VLDL, associated with PGLO, GFR, albuminuria, and YKL-40. Lipid perturbations may serve as novel targets to mitigate early kidney disease.

Sex- and gender-differences in chronic long-term complications of type 1 and type 2 diabetes mellitus in Italy

AIMS

This review summarizes the contribution of Italian diabetologists devoted to a better understanding of the complex relationship linking sex/gender and long-term complications of type 1 (T1DM) and type 2 diabetes (T2DM) over the last fifteen years.

DATA SYNTHESIS

Microvascular and macrovascular complications of diabetes show sex- and gender-related differences, involving pathophysiological mechanisms, epidemiological features and clinical presentation, due to the interaction between biological and psychosocial factors. These differences greatly impact on the progression of diabetes and its long-term complications, especially in the cardiovascular, renal and liver districts.

CONCLUSION

A better knowledge of such sex- and gender-related characteristics is required for a more precise patient phenotypization, and for the choice of a personalized antihyperglycemic treatment. Despite such mounting evidence, current diabetes clinical guidelines do not as yet adequately consider sex/gender differences.

Update on pathogenesis and diagnosis flow of normoalbuminuric diabetes with renal insufficiency

In recent decades, the prevalence of diabetic kidney disease has remained stable and appears to be a wide heterogeneity. Normoalbuminuric diabetes with renal insufficiency, which is characterized by a decline in the glomerular filtration rate in the absence of albuminuria, has been identified as an albuminuria-independent phenotype of diabetic kidney disease. Epidemiological data demonstrate that normoalbuminuric phenotype is prevalent. Compared to albuminuric phenotype, normoalbuminuric phenotype has distinct clinical characteristics and a wide heterogeneity of pathological features. Currently, the pathogenesis of normoalbuminuric phenotype remains unclear. Additionally, the flow of diagnosing normoalbuminuric phenotype is not perfect. In this article, we review the latest studies addressing the epidemiology, clinical characteristics, and pathology of normoalbuminuric phenotype. Based on the studies of clinical features and renal histopathologic changes, we attempt to propose an underlying pathogenesis model and a flow chart for diagnosing normoalbuminuric phenotype.

Diabetic kidney disease: new clinical and therapeutic issues. Joint position statement of the Italian Diabetes Society and the Italian Society of Nephrology on "The natural history of diabetic kidney disease and treatment of hyperglycemia in patients with type 2 diabetes and impaired renal function"

Aims

This joint document of the Italian Diabetes Society and the Italian Society of Nephrology reviews the natural history of diabetic kidney disease (DKD) in the light of the recent epidemiological literature and provides updated recommendations on anti-hyperglycemic treatment with non-insulin agents.

Data Synthesis

Recent epidemiological studies have disclosed a wide heterogeneity of DKD. In addition to the classical albuminuric phenotype, two new albuminuria-independent phenotypes have emerged, i.e., “nonalbuminuric renal impairment” and “progressive renal decline”, suggesting that DKD progression toward end-stage kidney disease (ESKD) may occur through two distinct pathways, albuminuric and nonalbuminuric. Several biomarkers have been associated with decline of estimated glomerular filtration rate (eGFR) independent of albuminuria and other clinical variables, thus possibly improving ESKD prediction. However, the pathogenesis and anatomical correlates of these phenotypes are still unclear. Also the management of hyperglycemia in patients with type 2 diabetes and impaired renal function has profoundly changed during the last two decades. New anti-hyperglycemic drugs, which do not cause hypoglycemia and weight gain and, in some cases, seem to provide cardiorenal protection, have become available for treatment of these individuals. In addition, the lowest eGFR safety thresholds for some of the old agents, particularly metformin and insulin secretagogues, have been reconsidered.

Conclusions

The heterogeneity in the clinical presentation and course of DKD has important implications for the diagnosis, prognosis, and possibly treatment of this complication. The therapeutic options for patients with type 2 diabetes and impaired renal function have substantially increased, thus allowing a better management of these individuals.

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.

Global, Regional, and National Burden of Diabetes-Related Chronic Kidney Disease From 1990 to 2019

BACKGROUND

Chronic kidney disease (CKD) is a public health problem largely caused by diabetes. The epidemiology of diabetes mellitus-related CKD (CKD-DM) could provide specific support to lessen global, regional, and national CKD burden.

METHODS

Data were derived from the GBD 2019 study, including four measures and age-standardized rates (ASRs). Estimated annual percentage changes and 95% CIs were calculated to evaluate the variation trend of ASRs.

RESULTS

Diabetes caused the majority of new cases and patients with CKD in all regions. All ASRs for type 2 diabetes-related CKD increased over 30 years. Asia and Middle socio-demographic index (SDI) quintile always carried the heaviest burden of CKD-DM. Diabetes type 2 became the second leading cause of CKD and CKD-related death and the third leading cause of CKD-related DALYs in 2019. Type 2 diabetes-related CKD accounted for most of the CKD-DM disease burden. There were 2.62 million incident cases, 134.58 million patients, 405.99 thousand deaths, and 13.09 million disability-adjusted life-years (DALYs) of CKD-DM worldwide in 2019. Age-standardized incidence (ASIR) and prevalence rate (ASPR) of type 1 diabetes-related CKD increased, whereas age-standardized death rate (ASDR) and DALY rate decreased for females and increased for males. In high SDI quintile, ASIR and ASPR of type 1 diabetes-related CKD remained the highest, with the slowest increase, whereas the ASDR and age-standardized DALY rate remained the lowest there. In high SDI quintile, ASIR of type 2 diabetes-related CKD was the highest, with the lowest increasing rate. In addition, type 2 diabetes-related CKD occurred most in people aged 80-plus years worldwide. The main age of type 2 diabetes-related CKD patients was 55-64 years in Asia and Africa. The prevalence, mortality, and DALY rate of type 2 diabetes-related CKD increased with age. As for incidence, there was a peak at 80 years, and after age of 80, the incidence declined. CKD-DM-related anemia was mainly in mild to moderate grade.

CONCLUSIONS

Increasing burden of CKD-DM varied among regions and countries. Prevention and treatment measures should be strengthened according to CKD-DM epidemiology, especially in middle SDI quintile and Asia.

Uric acid and risk of diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease (ESKD) in the Western world. Better control of glycemia and blood pressure, including renin-angiotensin system blockade (RASB), appear to have slowed DKD progression rate but have been unable to substantially decrease the annual incidence of new cases of DKD related ESKD. Thus, new treatment targets are needed. Higher levels of serum uric acid (SUA) have been associated with increased risk and progression of DKD in persons with types 1 (T1D) and 2 (T2D) diabetes and of chronic kidney disease (CKD) in general. This review presents the epidemiological, clinical, and clinical trial evidence regarding the hypothesis that SUA reduction could slow progression of DKD and/or CKD in general.

Serum uric acid is independently associated with diabetic nephropathy but not diabetic retinopathy in patients with type 2 diabetes mellitus

BACKGROUND

This study aims to investigate the relationship between serum uric acid (SUA) and the severity of diabetic nephropathy (DN) and diabetic retinopathy (DR) in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 2961 patients were enrolled in the present cross-sectional study. The severity of DN was determined by 24-hour urinary albumin excretion (UAE), which was classified as normal (UAE <30 mg/24 h), microalbuminuria (UAE: 30-299 mg/24 h), and macroalbuminuria (≥300 mg/24 h). The severity of DR was determined by non-mydriatic retinal photography and was classified as non-diabetic retinopathy (NDR), non-proliferative diabetic retinopathy (NPDR), and proliferative DR (PDR).

RESULTS

Patients with high SUA levels (≥420 μmol/L for males and ≥360 μmol/L for females) had a significantly higher prevalence of DN (UAE ≥30 mg/24 h, 39.3% vs 26.3%; p < 0.001), higher UAE levels (140 ± 297 vs 63 ± 175 mg/24 h; p < 0.001), and lower estimated glomerular filtration rate (eGFR; 79.3 ± 26.8 vs 96.8 ± 19.6 mL/min/1.73 m; p < 0.001), when compared with patients with normal SUA levels. However, the prevalence of DR, NPDR, or PDR did not differ. Furthermore, the concentration of SUA was higher in patients with higher severity of DN (all, p < 0.001) and patients with PDR (compared with NDR or NPDR, p < 0.05). SUA levels were positively associated with male gender, body mass index, the use of diuretics, triglyceride, low-density lipoprotein, and UAE levels, whereas they were negatively correlated with high-density lipoprotein, fasting blood glucose, glycosylated hemoglobin, and eGFR. After adjustment, SUA remained significantly associated with UAE (r = 0.069, p < 0.001).

CONCLUSION

For patients with T2DM, higher SUA levels are associated with higher UAE, lower eGFR, and higher prevalence of DN, but not DR.

Diabetic kidney disease: New clinical and therapeutic issues. Joint position statement of the Italian Diabetes Society and the Italian Society of Nephrology on "The natural history of diabetic kidney disease and treatment of hyperglycemia in patients with type 2 diabetes and impaired renal function"

AIMS

This joint document of the Italian Diabetes Society and the Italian Society of Nephrology reviews the natural history of diabetic kidney disease (DKD) in the light of the recent epidemiological literature and provides updated recommendations on anti-hyperglycemic treatment with non-insulin agents.

DATA SYNTHESIS

Recent epidemiological studies have disclosed a wide heterogeneity of DKD. In addition to the classical albuminuric phenotype, two new albuminuria-independent phenotypes have emerged, i.e., "nonalbuminuric renal impairment" and "progressive renal decline", suggesting that DKD progression toward end-stage kidney disease (ESKD) may occur through two distinct pathways, albuminuric and nonalbuminuric. Several biomarkers have been associated with decline of estimated glomerular filtration rate (eGFR) independent of albuminuria and other clinical variables, thus possibly improving ESKD prediction. However, the pathogenesis and anatomical correlates of these phenotypes are still unclear. Also the management of hyperglycemia in patients with type 2 diabetes and impaired renal function has profoundly changed during the last two decades. New anti-hyperglycemic drugs, which do not cause hypoglycemia and weight gain and, in some cases, seem to provide cardiorenal protection, have become available for treatment of these individuals. In addition, the lowest eGFR safety thresholds for some of the old agents, particularly metformin and insulin secretagogues, have been reconsidered.

CONCLUSIONS

The heterogeneity in the clinical presentation and course of DKD has important implications for the diagnosis, prognosis, and possibly treatment of this complication. The therapeutic options for patients with type 2 diabetes and impaired renal function have substantially increased, thus allowing a better management of these individuals.

Risk Factors for Kidney Disease in Type 1 Diabetes

OBJECTIVE

In type 1 diabetes (T1D), the course of microalbuminuria is unpredictable and timing of glomerular filtration rate (GFR) loss is uncertain. Thus, there is a need to identify the risk factors associated with the development of more advanced stages of kidney disease through large, long-term systematic analysis.

RESEARCH DESIGN AND METHODS

Multivariable Cox proportional hazards models assessed the association of baseline and time-dependent glycemic and nonglycemic risk factors for incident macroalbuminuria and reduced estimated GFR (eGFR; defined as <60 mL/min/1.73 m²) over a mean of 27 years in the Diabetes Control and Complications Trial (DCCT) cohort.

RESULTS

Higher mean HbA_1c (hazard ratio [HR] 1.969 per 1% higher level [95% CI 1.671-2.319]) and male sex (HR 2.767 [95% CI 1.951-3.923]) were the most significant factors independently associated with incident macroalbuminuria, whereas higher mean triglycerides, higher pulse, higher systolic blood pressure (BP), longer diabetes duration, higher current HbA_1c, and lower mean weight had lower magnitude associations. For incident reduced eGFR, higher mean HbA_1c (HR 1.952 per 1% higher level [95% CI 1.714-2.223]) followed by higher mean triglycerides, older age, and higher systolic BP were the most significant factors.

CONCLUSIONS

Although several risk factors associated with macroalbuminuria and reduced eGFR were identified, higher mean glycemic exposure was the strongest determinant of kidney disease among the modifiable risk factors. These findings may inform targeted clinical strategies for the frequency of screening, prevention, and treatment of kidney disease in T1D.

Association of kidney disease measures with risk of renal function worsening in patients with type 1 diabetes

BACKGROUND

Albuminuria has been classically considered a marker of kidney damage progression in diabetic patients and it is routinely assessed to monitor kidney function. However, the role of a mild GFR reduction on the development of stage ≥3 CKD has been less explored in type 1 diabetes mellitus (T1DM) patients. Aim of the present study was to evaluate the prognostic role of kidney disease measures, namely albuminuria and reduced GFR, on the development of stage ≥3 CKD in a large cohort of patients affected by T1DM.

METHODS

A total of 4284 patients affected by T1DM followed-up at 76 diabetes centers participating to the Italian Association of Clinical Diabetologists (Associazione Medici Diabetologi, AMD) initiative constitutes the study population. Urinary albumin excretion (ACR) and estimated GFR (eGFR) were retrieved and analyzed. The incidence of stage ≥3 CKD (eGFR < 60 mL/min/1.73 m2) or eGFR reduction > 30% from baseline was evaluated.

RESULTS

The mean estimated GFR was 98 ± 17 mL/min/1.73m² and the proportion of patients with albuminuria was 15.3% (n = 654) at baseline. About 8% (n = 337) of patients developed one of the two renal endpoints during the 4-year follow-up period. Age, albuminuria (micro or macro) and baseline eGFR < 90 ml/min/m² were independent risk factors for stage ≥3 CKD and renal function worsening. When compared to patients with eGFR > 90 ml/min/1.73m² and normoalbuminuria, those with albuminuria at baseline had a 1.69 greater risk of reaching stage 3 CKD, while patients with mild eGFR reduction (i.e. eGFR between 90 and 60 mL/min/1.73 m2) show a 3.81 greater risk that rose to 8.24 for those patients with albuminuria and mild eGFR reduction at baseline.

CONCLUSIONS

Albuminuria and eGFR reduction represent independent risk factors for incident stage ≥3 CKD in T1DM patients. The simultaneous occurrence of reduced eGFR and albuminuria have a synergistic effect on renal function worsening.

Risk of coronary artery disease and stroke according to sex and presence of diabetic nephropathy in type 1 diabetes

AIMS

To determine the effect of different stages of diabetic nephropathy (DN) and sex on the excess and absolute morbidity of coronary artery disease (CAD) and stroke in people with type 1 diabetes (T1D) in order to distinguish different cardiovascular disease (CVD) risk profiles in people with T1D.

MATERIALS AND METHODS

The study included 4410 people with T1D from the Finnish Diabetic Nephropathy Study (FinnDiane), divided by DN status, and a control population of 12 434 people without diabetes. CVD events were identified from the Finnish nationwide health registries. Cumulative incidences for CAD and stroke were calculated and standardized incidence ratios (SIRs) were estimated between participants with T1D and the control group, stratified by DN status and sex.

RESULTS

There were 487 incident CADs and 290 strokes at the end of 2014 (median follow-up 12.9 years). The cumulative incidence rates of CAD and stroke were similar in men and women within different nephropathy groups. The SIR for CAD was 7.5 (95% confidence interval [CI] 6.9-8.2), 17.2 (95% CI 14.9-19.5) in women and 5.3 (95% CI 4.7-5.9) in men. The women-to-men ratio of SIR increased by nephropathy group: 3.3, 3.7, 5.3 and 6.8 in the normo-, micro- and macroalbuminuria and end-stage renal disease (ESRD) groups, respectively. The SIR for stroke was 5.0 (95% CI 4.3-5.5), similar in men and women. The women-to-men ratio of SIR for stroke was 0.8, 1.3, 1.6 and 1.7, in the normo-, micro- and macroalbuminuria and ESRD groups, respectively. The SIR in participants with normoalbuminuria and an estimated glomerular filtration rate ≥90 mL/min/1.73 m² was 3.5 (95% CI 2.5-4.5) for CAD and 1.6 (95% CI 1.0-2.3) for stroke.

CONCLUSIONS

Although the excess CVD risk is several-fold greater in women compared to men, the absolute CVD risk in men and women was equal when nephropathy was taken into account. Even participants with normoalbuminuria and normal kidney function were found to have an excess CVD risk compared with the control group without diabetes.

Uric Acid and Diabetic Nephropathy Risk

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease (ESRD) in the western world. Current treatment methods, with better control of glycemia and blood pressure, including renin-angiotensin system blockade (RASB), appear to have slowed the DN progression rate but have not substantially decreased the annual incidence of new DN ESRD cases. Thus, new treatment targets are needed.

SUMMARY

Higher levels of serum uric acid (UA) are associated with increased risk of the clinical manifestations of DN in persons with types 1 and 2 diabetes. Also, UA is a strong predictor of DN progression. Two small, short-term, proof-of-concept clinical trials in which a minority of the patients had diabetes suggested that reduction of UA with allopurinol could decrease the rate of glomerular filtration rate (GFR) loss in persons with chronic kidney disease (CKD). However, a definitive trial to check whether UA reduction can benefit DN progression has not been conducted as yet. Preventing Early Renal Loss in Diabetes (PERL) is an ongoing trial in persons with type 1 diabetes and early to moderate GFR reduction. This 3-year randomized placebo controlled trial in 530 subjects is to check whether UA reduction with allopurinol can slow the rate of GFR decline as determined by the plasma disappearance of iohexol. Key Message: If the results of the PERL trial are positive, initiation of UA reduction treatment while GFR is relatively well preserved could delay ESRD in DN by 8-10 years, that is, considerably longer than the period that has been demonstrated for RASB. This could have important implications for the treatment of DN in particular and of CKD in general.

Normoalbuminuric kidney impairment in patients with T1DM: insights from annals initiative

BACKGROUND

We described, in a large sample of patients with type 1 diabetes mellitus (T1DM) and GFR ≤ 60 mL/min/1.73 m² (with or without albuminuria), the differences in the clinical features associated with the two different chronic kidney disease phenotypes and we investigated, in a subset of patients, the modulating role of albuminuria on kidney disease progression.

METHODS

Clinical data of 1395 patients with T1DM were extracted from electronic medical records.

RESULTS

Albuminuria was detected in 676 (48.5%) patients, with the remaining 719 (51.5%) patients having normoalbuminuric renal impairment. Those with albuminuria showed an evident worse cardiovascular risk profile as compared to patients with normoalbuminuria. A subgroup of 582 patients was followed up over a 4-year period. One hundred and twenty five patients (21.5%) showed a loss of eGFR > 30%. The proportion of patients reaching the renal outcome was significantly higher among those with baseline albuminuria as compared to patients with normoalbuminuria (P < 0.0001). At the multivariate logistic analysis microalbuminuria, macroalbuminuria and proliferative retinopathy were the only parameters independently associated to eGFR reduction.

CONCLUSIONS

The proportion of T1DM patients with normoalbuminuria renal impairment is high (about 50%). These patients have a slower eGFR decline as compared to that observed in patients with albuminuria renal impairment.

Diabetic Kidney Disease: Challenges, Progress, and Possibilities

Diabetic kidney disease develops in approximately 40% of patients who are diabetic and is the leading cause of CKD worldwide. Although ESRD may be the most recognizable consequence of diabetic kidney disease, the majority of patients actually die from cardiovascular diseases and infections before needing kidney replacement therapy. The natural history of diabetic kidney disease includes glomerular hyperfiltration, progressive albuminuria, declining GFR, and ultimately, ESRD. Metabolic changes associated with diabetes lead to glomerular hypertrophy, glomerulosclerosis, and tubulointerstitial inflammation and fibrosis. Despite current therapies, there is large residual risk of diabetic kidney disease onset and progression. Therefore, widespread innovation is urgently needed to improve health outcomes for patients with diabetic kidney disease. Achieving this goal will require characterization of new biomarkers, designing clinical trials that evaluate clinically pertinent end points, and development of therapeutic agents targeting kidney-specific disease mechanisms (e.g., glomerular hyperfiltration, inflammation, and fibrosis). Additionally, greater attention to dissemination and implementation of best practices is needed in both clinical and community settings.

INTRODUCTION