Albuminuria in type 2 (non-insulin-dependent) diabetes mellitus and impaired glucose tolerance in Pima Indians

Diagnostic criteria and etiopathogenesis of type 2 diabetes and its complications: Lessons from the Pima Indians

The Phoenix Epidemiology and Clinical Research Branch of the National Institute of Diabetes and Digestive and Kidney Diseases has conducted prospective studies of diabetes and its complications in the Pima Indians living in Arizona, USA for over 50 years. In this review we highlight areas in which these studies provided vital insights into the criteria used to diagnose type 2 diabetes, the pathophysiologic changes that accompany the development of type 2 diabetes, and the course and determinants of diabetes complications-focusing specifically on diabetic kidney disease. We include data from our longitudinal population-based study of diabetes and its complications, studies on the role of insulin resistance and insulin secretion in the pathophysiology of type 2 diabetes, and in-depth studies of diabetic kidney disease that include measures of glomerular function and research kidney biopsies. We also focus on the emerging health threat posed by youth-onset type 2 diabetes, which was first seen in the Pima Indians in the 1960s and is becoming an increasing issue worldwide.

Pima Indian Contributions to Our Understanding of Diabetic Kidney Disease

Prospective studies in informative populations are crucial to increasing our knowledge of disease. In this perspective, we describe a half century of studies in an American Indian population that transformed our understanding of kidney disease in type 2 diabetes, now recognized as the leading cause of kidney failure worldwide. Serial examinations conducted for many years that included the collection of data and samples across multiple domains captured an unprecedented volume of clinical, physiologic, morphometric, genomic, and transcriptomic data. This work permitted us to extensively characterize the course and determinants of diabetic kidney disease, its pathophysiologic underpinnings, and important secular trends of urgent concern to populations worldwide, including the emergence of youth-onset type 2 diabetes and its effect on development of diabetic kidney disease in midlife. By combining these data using the tools of integrative biology, we are developing new mechanistic insights into the development and progression of diabetic kidney disease in type 2 diabetes. These insights have already contributed to the identification and successful therapeutic targeting of a novel pathway in DKD. We anticipate that this work will continue to expand our understanding of this complex disease and influence its management in the coming years.

Remote Dwelling Location Is a Risk Factor for CKD Among Indigenous Canadians

Introduction

Rural and remote indigenous individuals have a high burden of chronic kidney disease (CKD) when compared to the general population. However, it has not been previously explored how these rates compare to urban-dwelling indigenous populations.

Methods

In a recent cross-sectional screening study, 1346 adults 18 to 80 years of age were screened for CKD and diabetes across 11 communities in rural and remote areas in Manitoba, Canada, as part of the First Nations Community Based Screening to Improve Kidney Health and Prevent Dialysis (FINISHED) program. An additional 284 Indigenous adults who resided in low-income areas in the city of Winnipeg, Manitoba, Canada were screened as part of the NorWest Mobile Diabetes and Kidney Disease Screening and Intervention Project.

Results

Our findings indicate that a gradient of CKD and diabetes prevalence exists for Indigenous individuals living in different geographic areas. Compared to urban-dwelling Indigenous individuals, rural-dwelling individuals had more than a 2-fold (2.1, 95% CI = 1.4-3.1) increase in diabetes whereas remote-dwelling individuals had a 4-fold (4.1, 95% CI = 2.8-6.0) increase, and more than a 3-fold (3.1, 95% CI = 2.2-4.5) increase in CKD prevalence.

Conclusion

Although these results highlight the relative importance of geography in determining the prevalence of diabetes and CKD in Indigenous Canadians, geography is but an important surrogate of other determinants, such as poverty and access to care.

Association of albuminuria with all-cause and cardiovascular disease mortality in diabetes: the Strong Heart Study

Objectives — To estimate the relative risks of albuminuria with all-cause and cardiovascular disease (CVD) mortality in a large cohort of American Indians with diabetes. Methods — A total of 1,953 diabetic participants in the Strong Heart Study were evaluated based on albuminuria categories at baseline examination. The Cox proportional hazards model was used to examine associations. Results — Of the 1,953 participants, 605 (31%) and 410 (21%) had microalbuminuria and macroalbuminuria, respectively, at baseline examination. Microalbuminuria (HR=1.42, 95% CI 1.15—1.77 for all-cause, and HR=1.48, CI 1.01—2.17 for CVD), and macroalbuminuria (HR=3.39, CI 2.71—4.25 for all-cause, and HR=3.74, CI 2.56—5.47 for CVD) were significant predictors for all-cause and CVD mortality after adjustment for other CVD risk factors. Conclusions — Results from the present study suggest that albuminuria is a strong independent predictor of all-cause and CVD Mortality in American Indians with diabetes.

The Prevalence of CKD in Rural Canadian Indigenous Peoples: Results From the First Nations Community Based Screening to Improve Kidney Health and Prevent Dialysis (FINISHED) Screen, Triage, and Treat Program

BACKGROUND

Indigenous Canadians have high rates of risk factors for chronic kidney disease (CKD), in particular diabetes. Furthermore, they have increased rates of complications associated with CKD, such as kidney failure and vascular disease. Our objective was to describe the prevalence of CKD in this population.

STUDY DESIGN

Cross-sectional cohort.

SETTING & PARTICIPANTS

Indigenous (First Nations) Canadians 18 years or older screened as part of the First Nations Community Based Screening to Improve Kidney Health and Prevent Dialysis (FINISHED) project, an initiative completed in 2015 that accomplished community-wide screening in 11 rural communities in Manitoba, Canada.

PREDICTORS

Indigenous ethnicity and geographic location (communities accessible by road compared with those accessible only by air).

OUTCOME

Prevalence of CKD, presumed based on a single ascertainment of urine albumin-creatinine ratio (UACR) ≥ 30mg/g and/or estimated glomerular filtration rate (eGFR)<60mL/min/1.73m(2).

MEASUREMENTS

Kidney function measured by eGFR (CKD-EPI creatinine equation) and UACR.

RESULTS

1,346 adults were screened; 25.5% had CKD, defined as UACR≥30mg/g or eGFR<60mL/min/1.73m(2). Communities accessible by road had a lower prevalence of CKD (17.6%) than more remote communities accessible only by air (34.4%). Of those screened, 3.3% had reduced kidney function (defined as eGFR<60mL/min/1.73m(2)). Severely increased albuminuria was present in 5.0% of those screened.

LIMITATIONS

Presumption of chronicity based on a single ascertainment. There is a possibility of sampling bias, the net direction of which is uncertain.

CONCLUSIONS

We found a 2-fold higher prevalence of CKD in indigenous Canadians in comparison to the general population and a prevalence of severely increased albuminuria that was 5-fold higher. This is comparable to patients with diabetes and/or hypertension. Public health strategies to screen, triage, and treat all Canadian indigenous peoples with CKD should be considered.

HbA1c Levels Are Associated with Chronic Kidney Disease in a Non-Diabetic Adult Population: A Nationwide Survey (KNHANES 2011-2013)

BACKGROUND

Many studies have reported an association between glycated hemoglobin A1c (HbA1c) and metabolic syndrome (MetS) in non-diabetes patients. Each component of MetS is in fact related to chronic kidney disease (CKD) incidence and progression. Therefore, HbA1c in non-diabetic mellitus (DM) may be intrinsically associated with the prevalence of CKD. The hypothesis of the present study was that high HbA1c in non-DM patients is associated with CKD.

PATIENTS AND METHODS

The total number of participants in this study was 24,594. The participants were divided into three groups according to their HbA1c levels: a Low group (<5.7% or <39 mmol/mol), a Middle group (5.7-6.0% or 39-42 mmol/mol), and a High group (>6.0% or >42 mmol/mol). The estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation.

RESULTS

The number of participants allocated to the Low, Middle, and High groups was 8,651, 4,634, and 1,387, respectively. Linear regression analyses were performed to evaluate the association between variables. Standardized β ± standard error was 0.25 ± 0.22 for waist circumference, 0.44 ± 0.20 for fasting glucose, -0.14 ± 0.30 for high-density lipoprotein cholesterol levels, 0.15 ± 2.31 for triglyceride levels, 0.21 ± 0.00 for systolic blood pressure, 0.10 ± 0.00 for diastolic blood pressure, and -0.22 ± 0.42 for eGFR (P < 0.001 for all variables). eGFR in non-diabetes participants was inversely associated with the HbA1c level, where eGFR decreased as HbA1c levels increased. Standardized βs were -0.04 ± 0.42 in multivariable analysis (P < 0.001). The proportion of participants with only MetS, only CKD, or both MetS and CKD was higher in the High group than in the Low and Middle groups.

CONCLUSION

High HbA1c in non-DM patients may be associated with CKD. Renal function in patients with high HbA1c levels may need to be monitored.

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.

Prevalence of chronic kidney disease in two major Indian cities and projections for associated cardiovascular disease

India is experiencing an alarming rise in the burden of non-communicable diseases, but data on the incidence of chronic kidney disease (CKD) are sparse. Using the Center for Cardiometabolic Risk Reduction in South Asia surveillance study (a population-based survey of Delhi and Chennai, India) we estimated overall, and age-, sex-, city-, and diabetes-specific prevalence of CKD, and defined the distribution of the study population by the Kidney Disease Improving Global Outcomes (KDIGO) classification scheme. The likelihood of cardiovascular events in participants with and without CKD was estimated by the Framingham and Interheart Modifiable Risk Scores. Of 12,271 participants, 80% had complete data on serum creatinine and albuminuria. The prevalence of CKD and albuminuria, age standardized to the World Bank 2010 world population, were 8.7% (95% confidence interval: 7.9 to 9.4%) and 7.1% (6.4 to 7.7%) respectively. Nearly 80% of patients with CKD had an abnormally high hemoglobin A1c (5.7 and above). Based on KDIGO guidelines, 6.0, 1.0, and 0.5% of study participants are at moderate, high, or very high risk for experiencing CKD-associated adverse outcomes. The cardiovascular risk scores placed a greater proportion of patients with CKD in the high-risk categories for experiencing cardiovascular events, when compared with participants without CKD. Thus one in 12 persons living in two of India’s largest cities have evidence of CKD, with features that put them at high risk for adverse outcomes.

Postpartum microalbuminuria after gestational diabetes: the impact of current glucose tolerance status

CONTEXT

It has been reported that women with a history of gestational diabetes mellitus (GDM) have an increased risk of microalbuminuria compared with that of their peers. Because previous GDM predicts an increased risk of prediabetes, which itself is associated with microalbuminuria, we hypothesized that current glucose intolerance may confound any association between GDM and microalbuminuria.

OBJECTIVE

The purpose of this study was to evaluate the relative impact of gestational and current dysglycemia on postpartum microalbuminuria in a cohort of women reflecting the full spectrum of gestational glucose tolerance from normal to mildly abnormal to GDM.

DESIGN/SETTING/PARTICIPANTS

In this prospective observational cohort study, 320 women underwent a glucose challenge test (GCT) and an oral glucose tolerance test (OGTT) in pregnancy, which identified 100 women with GDM, 58 with gestational impaired glucose tolerance, 90 with an abnormal GCT but a normal OGTT, and 72 with a normal GCT and OGTT. At 3 years postpartum, they underwent measurement of urine microalbumin and a repeat OGTT that identified 63 women with glucose intolerance (prediabetes/diabetes).

RESULTS

The postpartum urine microalbumin to creatinine ratio did not differ among the 4 gestational glucose tolerance groups (P = .23). Furthermore, on logistic regression analysis, GDM did not independently predict an elevated urine microalbumin to creatinine ratio of ≥1.5 g/mol of creatinine (odds ratio, 0.43; 95% confidence interval, 0.17-1.11), after adjustment for age, ethnicity, family history of diabetes, body mass index, blood pressure, estimated glomerular filtration rate, and current glucose intolerance. In contrast, current glucose intolerance independently predicted a urine microalbumin to creatinine ratio of ≥1.5 (odds ratio, 3.4; 95% confidence interval, 1.4-8.2, P = .005).

CONCLUSION

Current glucose intolerance, rather than previous GDM, may be associated with an increased risk of microalbuminuria in the early postpartum years.

Increased prevalence of albuminuria in individuals with higher range of impaired fasting glucose: the 2011 Korea National Health and Nutrition Examination Survey

AIMS

We investigated the prevalence of albuminuria across a range of fasting plasma glucose (FPG), including normal fasting glucose (NFG), impaired fasting glucose (IFG), and diabetes.

METHODS

A total of 5202 subjects who participated in the fifth Korea National Health and Nutrition Examination Survey were enrolled. Spot urine samples were taken and the albumin-creatinine ratio was calculated for each patient. Subjects were divided into five groups according to FPG levels: <5.0 (NFG1, n=1,905), 5.0-5.5 (NFG2, n=1,784), 5.6-6.0 (IFG1, n=727), 6.1-6.9 (IFG2, n=268), and ≥7.0 (diabetes, n=518) mmol/L. Analysis of covariance tests and logistic regression were used.

RESULTS

The rates of albuminuria were 4.1%, 6.0%, 7.6%, 12.3%, and 23.4% in the NFG1, NFG2, IFG1, IFG2 and diabetes groups, respectively (P<0.01 for the trend). The rate of albuminuria in the IFG2 group was significantly higher than in the IFG1 group, even after adjustment for age, gender, hypertension, and obesity. The odds ratio for the presence of albuminuria in the IFG2 group was 1.87 (95% CI, 1.19-2.94), using the NFG1 group as a control in logistic regression analyses.

CONCLUSIONS

Albuminuria is more prevalent in subjects in the higher range of IFG. Therefore, strategies to reduce albuminuria should be emphasized especially in these subjects.

Prevalence and determinants of diabetic nephropathy in Korea: Korea national health and nutrition examination survey

BACKGROUND

Diabetic nephropathy is a leading cause of end stage renal disease and is associated with an increased risk of cardiovascular mortality. It manifests as albuminuria or impaired glomerular filtration rate (GFR), and the prevalence of diabetic nephropathy varies with ethnicity. The prevalence of diabetic nephropathy and its determinants in Korean adults have not previously been studied at the national level. This cross-sectional study was undertaken to ascertain the prevalence and determinants of albuminuria and chronic kidney disease (CKD) in Korean patients with diabetes.

METHODS

The Korea National Health and Nutrition Examination Survey (KNHANES) V, conducted in 2011, was used to define albuminuria (n=4,652), and the dataset of KNHANES IV-V (2008-2011) was used to define CKD (n=21,521). Selected samples were weighted to represent the entire civilian population in Korea. Albuminuria was defined as a spot urine albumin/creatinine ratio >30 mg/g. CKD was defined as a GFR <60 mL/min/1.73 m(2).

RESULTS

Among subjects with diabetes, 26.7% had albuminuria, and 8.6% had CKD. Diabetes was associated with an approximate 2.5-fold increased risk of albuminuria, with virtually no difference between new-onset and previously diagnosed diabetes. Only systolic blood pressure was significantly associated with albuminuria, and old age, high serum triglyceride levels, and previous cardiovascular disease (CVD) were related with CKD in subjects with diabetes.

CONCLUSION

Korean subjects with diabetes had a higher prevalence of albuminuria and CKD than those without diabetes. Blood pressure was associated with albuminuria, and age, triglyceride level, and previous CVD were independent determinants of CKD in subjects with diabetes.

Correlation between prediabetes conditions and microalbuminuria

Background

Impaired fasting glucose (IFG), and impaired glucose tolerance (IGT) are two prediabetes conditions which have some correlation with macrovascular disorders. The risk of microvascular complications in these groups is not clear.

Objectives

The prevalence of albuminuria in subjects with IFG and IGT was evaluated in the present study.

Patients and Methods

In this study three groups of subjects were entered (45 subjects in each group): IFG, IGT, and normal glucose tolerance as control. The urine albumin-creatinine ratio was studied in morning spot urine samples to detect microalbuminuria. The subjects were followed up for two years, and blood sugar and urine albumin and glycosylated hemoglobin (HbA1C) were measured every 6 months.

Results

The prevalence rate of microalbuminuria was 15.5% in the prediabetic groups, while no one had microalbuminuria in the control group (P = 0.005). The prevalence of microalbuminuria in patients with IFG or IGT was not significantly different (17.8% vs. 13.3%) (P = 0.4). Fourteen subjects (4 in IFG group and 10 in IGT group) developed diabetes mellitus within a 2-year follow-up period (P = 0.1). Thirty six percent of subjects with albuminuria, and twelve percent of subjects without albuminuria progressed to diabetes mellitus during a 2-year follow-up (P = 0.02, odd ratio = 4.1; CI95%, 1.13-15.1).

Conclusions

The risk of microalbuminuria in prediabetic subjects is high, and probably prediabetic subjects are at higher risk of progression to diabetes mellitus. We suggest periodically evaluation of albuminuria in prediabetic patients after the diagnosis.

The role of non-coding RNAs in diabetic nephropathy: potential applications as biomarkers for disease development and progression

Diabetic nephropathy, a progressive kidney disease that develops secondary to diabetes, is the major cause of chronic kidney disease in developed countries, and contributes significantly to increased morbidity and mortality among individuals with diabetes. Although the causes of diabetic nephropathy are not fully understood, recent studies demonstrate a role for epigenetic factors in the development of the disease. For example, non-coding RNA (ncRNA) molecules, including microRNAs (miRNAs), have been shown to be functionally important in modulating renal response to hyperglycemia and progression of diabetic nephropathy. Characterization of miRNA expression in diabetic nephropathy from studies of animal models of diabetes, and in vitro investigations using different types of kidney cells also support this role. The goal of this review, therefore, is to summarize the current state of knowledge of specific ncRNAs involved in the development of diabetic nephropathy, with a focus on the potential role of miRNAs to serve as sensitive, non-invasive biomarkers of kidney disease and progression. Non-coding RNAs are currently recognized as potentially important regulators of genes involved in processes related to the development of diabetic nephropathy, and as such, represent viable targets for both clinical diagnostic strategies and therapeutic intervention.

Pré-diabetes: diagnóstico, avaliação de complicações crônicas e tratamento

O diabetes melito do tipo 2 (DM2) é responsável por 90% dos casos de diabetes e está associado a complicações micro e macrovasculares de elevada morbimortalidade. Os indivíduos com maior risco de desenvolvimento de DM incluem aqueles com glicemia de jejum alterada (GJA) e tolerância diminuída à glicose (TDG) e especialmente aqueles com as duas condições combinadas. Esses indivíduos fazem parte de um grupo hoje conhecido como pré-diabetes. Aproximadamente 25% dos indivíduos com pré-diabetes desenvolverão DM2 em três a cinco anos. A hiperglicemia, na ausência de DM, também foi associada ao aumento no risco de doença cardiovascular. Estudos demonstraram que mudanças no estilo de vida e intervenções medicamentosas são efetivas em retardar ou prevenir o DM2 em pacientes com pré-diabetes. GJA e TDG estão associadas ao desenvolvimento de DM2 e, apesar das controvérsias, a maioria dos estudos epidemiológicos reforça a importância dessas duas condições também no desenvolvimento de doença micro e macrovascular. Assim, intervenções em pacientes com pré-diabetes são importantes na prevenção primária do DM2 e de suas complicações crônicas.

Glucose tolerance status is a better predictor of diabetes and cardiovascular outcomes than metabolic syndrome: a prospective cohort study

BACKGROUND

To evaluate the importance of oral glucose tolerance test (OGTT) in predicting diabetes and cardiovascular disease in patients with and without Metabolic Syndrome from a population treated in a primary care unit.

RESEARCH DESIGN AND METHODS

A prospective cohort study was conducted with subjects regularly attending the primary care unit of Hospital de Clínicas de Porto Alegre. Participants underwent a 75 g OGTT. Metabolic syndrome definition was based on the criteria of IDF/AHA/NHLBI-2010.

RESULTS

Participants mean age was 61 ± 12 years (males: 38%; whites: 67%). Of the 148 subjects included, 127 (86%) were followed for 36 ± 14 months, 21 (14%) were lost. Subjects were classified into four groups based on baseline OGTT: 29% normal (n = 43), 28% impaired fasting glucose (IFG; n = 42), 26% impaired glucose tolerance (IGT; n = 38), and 17% diabetes (n = 25). Metabolic syndrome prevalence was lower in normal group (28%), intermediate in IFG (62%) and IGT (65%) groups, and higher among subjects with diabetes (92%; P <0.001). Incidence of diabetes increased along with the stages of glucose metabolism disturbance (normal: 0%, IFG: 16%, IGT: 28%; P = 0.004). No patient with normal OGTT developed diabetes, regardless metabolic syndrome presence. Diabetes at baseline was the major determinant of cardiovascular disease occurrence (normal: 0%, IFG: 4%, IGT: 0%, diabetes: 24%; P = 0.001). In Cox-regression analysis, only the 2 h OGTT results were associated with diabetes (OR = 1.03; 95%CI 1.01-1.06; P <0.001) and cardiovascular disease development (OR = 1.013; 95%CI 1.002-1.025; P = 0.024).

CONCLUSIONS

In this sample of subjects undergoing diabetes screening, the OGTT predicted diabetes and cardiovascular disease more effectively than the metabolic syndrome status.

Prevalence, risk factors and awareness of albuminuria on a Canadian First Nation: a community-based screening study

BACKGROUND

Both diabetic and non-diabetic end stage renal disease (ESRD) are more common among Canadian First Nations people than among the general Canadian population. The purpose of this research was to determine the prevalence of and risk factors for albuminuria in a Canadian First Nation population at high risk for ESRD and dialysis.

METHODS

Data from a community-based screening study of 483 residents of a Plains Ojibway First Nation in Manitoba was used. Participants provided random urine samples. Proteinuria was defined as any dipstick positive for protein (≥1 g/L) or those with ACR in the macroalbuminuric range (≥30 mg/mmol) on at least one sample. Microalbuminuria was defined as ACR ≥2 mg/mmol for males and ≥2.8 mg/mmol for females. Other measures included fasting glucose, haemoglobin A1c, triglycerides, cholesterol, blood pressure, height, weight and waist and hip circumferences.

RESULTS

Twenty percent of study participants had albuminuria, (5% proteinuria and 15% microalbuminuria). Of participants with diabetes, 42% (56/132) had albuminuria compared to 26% (7/27) among those with impaired fasting glucose and 10% (30/303) among those with normal glucose tolerance. Only 5.3% of those with albuminuria were aware of any degree of renal disease. In a multivariate logistic regression, independent associations with albuminuria were male gender [p = 0.002], increasing fasting glucose [p <0.0001], years diagnosed with diabetes [p = 0.03], increasing systolic blood pressure [p = 0.009], and increasing body mass index (BMI) [p = 0.04].

CONCLUSIONS

The independent association between BMI and albuminuria has not been previously reported among indigenous populations. There is a high prevalence of albuminuria in this Canadian First Nation population; the high proportion of patients with diabetes and undiagnosed kidney disease demonstrates the need for screening, education and intervention to halt the progression and development of albuminuria and ultimately ESRD and CVD.

ELMO1 variants and susceptibility to diabetic nephropathy in American Indians

Variants in the engulfment and cell motility 1 gene, ELMO1, have previously been associated with kidney disease attributed to type 2 diabetes. The Pima Indians of Arizona have high rates of diabetic nephropathy, which is strongly dependent on genetic determinants; thus, we sought to investigate the role of ELMO1 polymorphisms in mediating susceptibility to this disease in this population. Genotype distributions were compared among 141 individuals with nephropathy and 416 individuals without heavy proteinuria in a family study of 257 sibships, and 107 cases with diabetic ESRD and 108 controls with long duration diabetes and no nephropathy. We sequenced 17.4 kb of ELMO1 and identified 19 variants. We genotyped 12 markers, excluding those in 100% genotypic concordance with other variants or with a minor allele frequency <0.05, plus 21 additional markers showing association with ESRD in earlier studies. In the family study, the strongest evidence for association was with rs1345365 (odds ratio [OR]=2.42 per copy of A allele [1.35-4.32]; P=0.001) and rs10951509 (OR=2.42 per copy of A allele [1.31-4.48]; P=0.002), both of which are located in intron 13 and are in strong pairwise linkage disequilibrium (r(2)=0.97). These associations were in the opposite direction from those observed in African Americans, which suggests that the relationship between diabetic kidney disease and ELMO1 variation may involve as yet undiscovered functional variants or complex interactions with other biological variables.

Predictive value of albuminuria in American Indian youth with or without type 2 diabetes

OBJECTIVE

To examine the prognostic significance of elevated albuminuria in youth with type 2 diabetes.

PATIENTS AND METHODS

Cross-sectional and prospective studies were conducted on Pima Indian youth aged 5 to 19 years at baseline who were examined between July 1, 1982, and December 31, 2007. Prevalence and sequential changes in the level of microalbuminuria (30 < or = albumin-to-creatinine ratio [ACR] < 300 mg/g) and macroalbuminuria (ACR > or = 300 mg/g) and incidence of macroalbuminuria were computed according to the presence or absence of type 2 diabetes.

RESULTS

The prevalence of microalbuminuria and macroalbuminuria was 6.5% and 0.6% in the 3856 nondiabetic youth and 18.5% and 2.9% in the 103 youth with diabetes, respectively. One hundred forty-one of 187 (75.4%) nondiabetic youth, but only 1 of 14 (7.1%) diabetic youth with an elevated ACR (> or =30 mg/g) regressed to an undetectable or normal ACR (<30 mg/g) on subsequent examination. In a subset of 2666 youth with a median follow-up of 8.1 years, 36 nondiabetic and 30 diabetic youth with baseline ACRs of <300 mg/g developed macroalbuminuria. For a given ACR, the incidence of macroalbuminuria was 15.9-fold (95% confidence interval: 11.1-22.6) higher in the diabetic than in the nondiabetic youth.

CONCLUSIONS

Elevated albuminuria is infrequent and largely transient in nondiabetic youth, but it is relatively frequent and largely persistent in those with diabetes. Microalbuminuria in youth with type 2 diabetes strongly predicts progression to macroalbuminuria, which supports annual screening for albuminuria.

Genome-wide SNP genotyping study using pooled DNA to identify candidate markers mediating susceptibility to end-stage renal disease attributed to Type 1 diabetes

AIMS

Genetic factors play a major role in the progression of kidney disease in diabetes. To identify candidate single nucleotide polymorphisms (SNPs) with potential effects on susceptibility to end-stage renal disease (ESRD), we performed a whole genome association scan using pooled DNA from Caucasian individuals with Type 1 diabetes.

METHODS

We utilized the Illumina Infinium II HumanHap 550 beadchip platform to genotype 555 352 SNPs in DNA pools comprised of 547 cases with ESRD and 549 control subjects with Type 1 diabetes duration > 20 years and no ESRD. Pooled probe intensity was used to predict mean allele frequency (MAF) for each locus. Individual genotyping was performed using the iPLEX assay in conjunction with the MassARRAY platform (Sequenom).

RESULTS

We identified 2870 markers showing substantial differences in MAF (5.0-10.7%) between pools. To initiate validation of these findings, we genotyped 22 high-ranking markers in 462 individuals with ESRD and 470 unaffected control subjects selected from the genome-wide SNP genotyping study sample. We observed the strongest evidence for association between ESRD and rs1749824, located in the ZMIZ1 gene [OR = 1.47 (1.21-1.78) per copy of T allele; P = 8.1 x 10(-5)] and rs9298190, located in the musculin gene [OR = 1.56 (1.28-1.91) per copy of C allele; P = 1.6 x 10(-5)]. Evidence for nominal association with markers in or near the IRS2, TMPO, BID, KLRA1, ELMO1 and CNDP1 genes was also observed (P < or = 0.0006).

CONCLUSIONS

These findings identify several novel loci which may contribute to ESRD susceptibility in individuals with Type 1 diabetes.

Changes in albumin excretion in the diabetes prevention program

OBJECTIVE

Increased urinary albumin excretion rates have been linked to nephropathy and macrovascular disease. We here describe the baseline prevalence and effect of Diabetes Prevention Program (DPP) interventions on the development and reversal of elevated albumin excretion.

RESEARCH DESIGN AND METHODS

Urine albumin-to-creatinine ratios (ACRs) were calculated from untimed urine collections. Analyses compared participants by treatment group, diabetes and hypertension status, and use of ACE inhibitors or angiotensin II receptor blockers (ARBs).

RESULTS

Elevated ACR levels (>or=30 mg/g creatinine) were present at baseline in 198 (6.2%) of 3,188 participants: placebo 5.3%, metformin 6.5%, and intensive lifestyle (ILS) 6.8%. Of the 2,802 with ACR measurements at baseline and at the end of the study, the percentage with elevated levels declined (incident and regression) from 6.2 to 6.1%, with no significant differences between the groups even with adjustment for ACE inhibitor and ARB use. The odds of developing an elevated ACR were 59% higher for a participant who developed diabetes compared with one who did not.

CONCLUSIONS

At entry into the DPP, an elevated ACR was present in 6.2%. Despite the marked decrease in progression to diabetes and the improvement in insulin resistance and other cardiovascular risk markers in the ILS and metformin groups, there was no improvement in ACR, on average, in those two groups. However, the frequency of an elevated ACR was higher in participants who developed diabetes. An increased ACR may have multiple causes, thus obscuring the improvements that might have been expected with the reduction in insulin resistance seen in the DPP.

Diabetic nephropathy in American Indians, with a special emphasis on the Pima Indians

Diabetes affects American Indians disproportionately compared with other racial/ethnic groups in the United States and is almost exclusively type 2 diabetes. Much of our knowledge about diabetes in American Indians comes from studies in a few tribes. The most extensively studied American Indians are the Pima Indians from the Gila River Indian Community in Arizona, who participated in a longitudinal study of diabetes and its complications between 1965 and 2007. They have one of the highest reported incidence and prevalence of type 2 diabetes in the world, and kidney disease attributable to diabetes is a major cause of morbidity and mortality. In this article, we examine the course, determinants, and trends of diabetic kidney disease in American Indians, with special emphasis on studies conducted in the Pima Indians. We also review therapeutic strategies for managing diabetic kidney disease.

Quantitative assessment of serum and urinary polyclonal free light chains in patients with type II diabetes: an early marker of diabetic kidney disease?

OBJECTIVE

Free light chains (FLCs) are bi-products of normal immunoglobulin synthesis and are predominately removed from the circulation by the kidneys. This study assessed polyclonal FLCs as a novel biomarker of early diabetic kidney disease.

RESEARCH DESIGN/METHODS

Serum and urinary FLCs were assessed by the immunoassay Freelite, in white and South-Asian patients with type II diabetes recruited from the United Kingdom Asian Diabetes Study.

RESULTS

The incidence of monoclonal proteins in this diabetic population was 1.9%. Type II diabetic patients had significantly raised concentrations of serum polyclonal FLCs before overt renal impairment developed (p < 0.001). Both kappa and lambda FLCs correlated with all tested markers of renal function; in particular cystatin-C: Spearman's coefficient (R) = 0.55 (p < 0.01) and R = 0.56 (p < 0.01), respectively. The South-Asian diabetic patients had higher serum polyclonal FLCs than Caucasian diabetic patients and this was independent of renal function. Urinary FLCs concentrations were raised in diabetic patients (p < 0.001). The majority (68%) of diabetic patients with normal urinary albumin:creatinine ratios (ACRs) had abnormal urinary FLC:creatinine ratios. Both kappa and lambda FLC concentrations correlated with urinary ACR: R = 0.32, p < 0.01 and R = 0.25, p < 0.01 respectively.

CONCLUSIONS

Type II diabetic patients can have significantly raised concentrations of serum and urinary polyclonal FLCs before overt renal disease occurs. These novel findings provide the basis for future studies to assess whether polyclonal FLCs could provide a useful tool for early diagnosis of diabetic kidney disease.

Prevalence and risk factors of diabetic nephropathy in an urban South Indian population: the Chennai Urban Rural Epidemiology Study (CURES 45)

OBJECTIVE

The aim of this study was to determine the prevalence of diabetic nephropathy among urban Asian-Indian type 2 diabetic subjects.

RESEARCH DESIGN AND METHODS

Type 2 diabetic subjects (n = 1,716), inclusive of known diabetic subjects (KD subjects) (1,363 of 1,529; response rate 89.1%) and randomly selected newly diagnosed diabetic subjects (NDD subjects) (n = 353) were selected from the Chennai Urban Rural Epidemiology Study (CURES). Microalbuminuria was estimated by immunoturbidometric assay and diagnosed if albumin excretion was between 30 and 299 microg/mg of creatinine, and overt nephropathy was diagnosed if albumin excretion was > or = 300 microg/mg of creatinine in the presence of diabetic retinopathy, which was assessed by stereoscopic retinal color photography.

RESULTS

The prevalence of overt nephropathy was 2.2% (95% CI 1.51-2.91). Microalbuminuria was present in 26.9% (24.8-28.9). Compared with the NDD subjects, KD subjects had greater prevalence rates of both microalbuminuria with retinopathy and overt nephropathy (8.4 vs. 1.4%, P < 0.001; and 2.6 vs. 0.8%, P = 0.043, respectively). Logistic regression analysis showed that A1C (odds ratio 1.325 [95% CI 1.256-1.399], P < 0.001), smoking (odds ratio 1.464, P = 0.011), duration of diabetes (1.023, P = 0.046), systolic blood pressure (1.020, P < 0.001), and diastolic blood pressure (1.016, P = 0.022) were associated with microalbuminuria. A1C (1.483, P < 0.0001), duration of diabetes (1.073, P = 0.003), and systolic blood pressure (1.031, P = 0.004) were associated with overt nephropathy.

CONCLUSIONS

The results of the study suggest that in urban Asian Indians, the prevalence of overt nephropathy and microalbuminuria was 2.2 and 26.9%, respectively. Duration of diabetes, A1C, and systolic blood pressure were the common risk factors for overt nephropathy and microalbuminuria.

Genome-wide scan for type 1 diabetic nephropathy in the Finnish population reveals suggestive linkage to a single locus on chromosome 3q

Diabetic nephropathy (DN) is the primary cause of morbidity and mortality in patients with type 1 as well as type 2 diabetes, and accounts for 40% of end-stage renal disease in the Western world. Familial clustering of DN suggests importance of genetic factors in the development of the disease. In the present study, we performed a two-stage genome-wide scan to search for chromosomal loci containing susceptibility genes for nephropathy in patients with type 1 diabetes. In total, 83 discordant sib pairs (DSPs), sibs concordant for type 1 diabetes but discordant for nephropathy, were collected from Finland, a homogeneous population with one of the highest incidences of type 1 diabetes. To map loci for DN, we applied DSP analysis to detect linkage. In the initial scan, 73 DSPs were typed using 900 markers with an average intermarker distance of approximately 4 cM. Multipoint DSP analysis identified five chromosome regions (3q, 4p, 9q, 16q, and 22p) with maximum logarithm of odds (LOD) score (MLS) >or=1.0 (corresponding to a nominal P-value <or=0.015). In the second stage, additional 43 markers flanking these five loci were genotyped in all 83 DSPs. Using simulations, we determined the empirical threshold with LOD score of 1.76 and 3.12 for suggestive and significant linkage, respectively. No locus reached the genome-wide significance of 5%. However, one locus on 3q reached suggestive linkage with MLS of 2.67 (P=4.4 x 10(-4)). These results, together with data from others, suggest that the locus on 3q most likely has a susceptibility gene for DN.

Assessment of glomerular filtration rate in addition to albuminuria is important in managing type II diabetes

Although much emphasis has been placed on screening for albuminuria in type II diabetic patients, less attention has been focused on the role of glomerular filtration rate (GFR) in the assessment of risk. Herein, we examined the association between GFR and vascular complications in a consecutive cohort of 5174 type II diabetic patients between 1995 and 2000. Renal function was assessed by GFR (estimated by Modification of Diet in Renal Disease equation). The frequency of chronic kidney disease (CKD) as defined by GFR <60 ml/min/1.73 m(2), micro- and macrovascular complications, and their associations were analyzed. In this study cohort, 6% had serum creatinine > or =150 micromol/l and 15.8% had CKD. After adjustment for potential confounders, including urinary albumin excretion, odds ratios [95% confidence interval (CI)] across different stages of estimated GFR (> or =90, 60-89, 30-59, 15-29, <15 ml/min/1.73 m(2)) for macrovascular disease were 1.00, 1.42 [1.12-1.80], 1.80 [1.32-2.45], 2.74 [1.64-4.56], and 4.05 [1.77-9.26], respectively (P for trend <0.001); for retinopathy were 1.00, 1.23 [1.04-1.46], 1.80 [1.40-2.30], 2.05 [1.25-3.37], and 4.12 [1.56-10.90], respectively (P for trend <0.001); for sensory neuropathy were 1.00, 1.53[1.27-1.85], 2.09 [1.58-2.76], 4.32 [2.41-7.77], and 3.16 [1.25-8.02], respectively (P for trend <0.001); and for microalbumuria (with GFR <15 ml/min/1.73 m(2) excluded from the analysis) were 1.00, 1.51 [1.30-1.75], 5.80 [4.52-7.44], and 52.5 [16.4-168.2] respectively (P for trend <0.001). Measurement of serum creatinine alone without GFR may underestimate renal impairment in type II diabetic patients. Decreasing GFR was significantly associated with increasing frequency of micro- and macrovascular complications.

Detection of early nephropathy in Mexican patients with type 2 diabetes mellitus

BACKGROUND

The aims of this study were to determine the prevalence of early nephropathy in patients with type 2 diabetes mellitus (DM2) attending primary care medical units and to identify risk factors for nephropathy in this population.

METHOD

Seven hundred fifty-six patients with DM2 attending 3 primary care medical units were randomly selected. In a first interview, an albuminuria dipstick and a detailed clinical examination were performed, and a blood sample was obtained. If the albuminuria dipstick was positive, then a 24-hour urine collection was obtained within the next 2 weeks to quantify the albuminuria. In the blood sample, glucose, creatinine, and lipids were determined. Glomerular filtration rate was calculated using the Modification of Diet in Renal Disease Study equation. Demographics and medical history were recorded from clinical examination and medical charts.

RESULTS

Prevalence of early nephropathy (EN) was 40%, normal function (NF) was found in 31%, and overt nephropathy (ON) in 29%. Patients with more severe kidney damage were older (NF: 54 +/- 10; EN: 60 +/- 11; ON: 63 +/- 10 years, P < 0.05) and had a higher proportion of illiteracy (NF: 11%, EN: 17%; ON: 25%, P < 0.05). The more severe the nephropathy, the longer the median duration of DM2 (NF: 6.0; EN: 7.0; ON: 11.0 years; P < 0.05); the higher the frequency of hypertension (NF: 38%; EN: 52%; ON: 68%; P < 0.05); and the higher the systolic blood pressure (NF: 126 +/- 21; EN: 130 +/- 19; ON: 135 +/- 23 mm Hg; P < 0.05). Both nephropathy groups had a significantly higher proportion of family history of nephropathy (NF: 4%; EN: 9%; ON: 13%) and a higher frequency of cardiovascular disease (NF: 5%; EN: 12%; ON: 25%), whereas only patients with ON had peripheral neuropathy (NF: 21%; EN: 22%; ON: 43%) and retinopathy (NF: 12%; EN: 18%; ON: 42%) more frequently than others. Fasting glucose was poorly controlled in all groups (NF: 186 +/- 70; EN: 173 +/- 62; ON: 183 +/- 73 mg/dL). Large body mass index (NF: 29.3 +/- 5.3; EN: 29.7 +/- 5.6; ON: 29.6 +/- 5.5 kg/m(2)), smoking (NF: 45%; EN: 43%; ON: 44%), and alcoholism (NF: 29%, EN: 29%; ON: 26%) were frequently found in this population, although there were no significant differences. In the multivariate analysis, only age, duration of DM2, and presence of retinopathy, hypertension, and cardiovascular disease were significantly associated with nephropathy.

CONCLUSIONS

Two thirds of Mexican patients with DM2 attending primary health care medical units had nephropathy, 40% of whom were at an early stage of the disease. Many modifiable and nonmodifiable risk factors were present in these patients, but the most significant predictors for nephropathy are older age, longer duration of diabetes, and the presence of retinopathy, hypertension, and cardiovascular disease.

Impact of lifestyle on prevalence of kidney disease in Pima Indians in Mexico and the United States

Pima Indians in the United States and Mexico share a common genetic background but have very different lifestyles. Comparisons were made of the frequency of obesity, diabetes, hypertension, and kidney disease in these geographically separated but susceptible populations. Mexican Pimas had higher levels of physical activity, less obesity, and a lower prevalence of diabetes than their US Pima counterparts. Mean blood pressure rose with worsening glucose tolerance, and the prevalence of elevated urinary albumin excretion was higher in patients with diabetes than in those without, regardless of whether they lived in the United States or Mexico. These findings illustrate the importance of lifestyle in the development of diabetes and in the subsequent occurrence of diabetic kidney disease.

Diabetes mellitus in children and adolescents

Until recently, diabetes in children was virtually synonymous with type 1 diabetes mellitus, whereas type 2 diabetes was a disease of middle age and the elderly. Over the past 10-20 years, an alarming increase in the prevalence of type 2 diabetes has been reported from pediatric diabetes centers in North America and elsewhere in the world. Lifestyle factors responsible for the worldwide epidemic of overweight and obesity are responsible for the increase in the prevalence of type 2 diabetes in adults and children. This article briefly discusses the diagnosis and major types of diabetes in children but focuses on aspects of type 2 diabetes in children and adolescents, including demographics, pathophysiology, clinical presentation, screening, prevention and treatment. The identification of children at risk for type 2 diabetes and the implementation of community-wide preventive programs will be essential to reverse the tide. The availability of calorie dense "fast foods," candy, and sugared soft drinks must be restricted in schools and other venues frequented by children. Parents must limit the amount of time their children spend watching television and playing computer games. After-school programs that promote physical activity should be a priority of local and central governmental agencies. Prevention will only succeed if governments and local communities recognize that childhood obesity is an important public health problem and provide an environment that promotes changes in lifestyle that prevent and reverse obesity.

Kidney disease among the Zuni Indians: The Zuni Kidney Project

BACKGROUND

There is an epidemic of kidney disease among the Zuni Indians. In collaboration with health care providers and research institutions, the Zuni Pueblo established the Zuni Kidney Project to reduce the burden of kidney disease.

METHODS

The Zuni Kidney Project conducted a population-based, cross-sectional survey to estimate the prevalence of albuminuria, hematuria, and related risk factors. Neighborhood household clusters served as the sampling frame. Participants completed a questionnaire, donated blood and urine samples, and had blood pressure, height, and weight measured. This survey provided the foundation for ongoing studies to identify genetic and environmental risk factors for disease susceptibility and progression.

RESULTS

Age and gender distributions among survey participants were similar to those in the eligible Zuni population. Prevalence of incipient albuminuria (IA) (0.03< or = urine albumin:creatinine ratio, UACR <0.3) and overt albuminuria (OA) (UACR < 0.3) were higher among diabetics [IA 34.3% (28.3, 40.4%); OA 18.6% (13.7, 23.6%)] than nondiabetics [IA 11.1% (9.3, 12.8%); OA 1.7% (1.0, 2.5%)]. Nondiabetics comprised 58.6% (52.2, 65.0%) and 30.9% (19.9, 41.9%) of participants with IA and OA, respectively. The prevalence of hematuria was higher among diabetics [> or = trace 47.0% (40.7, 53.4); > or =50 red blood cell/microL 25.8% (20.3, 31.4%)] than nondiabetics [> or = trace 31.1% (28.5, 33.7%); > or =50 red blood cell/microL 16.6% (14.5, 18.7%)]. Hypertension was associated with albuminuria among diabetic and nondiabetic participants. Hypercholesterolemia was associated with albuminuria among nondiabetic participants. Diabetes and alcohol use were associated with hematuria.

CONCLUSION

The high prevalences of albuminuria among nondiabetics and of hematuria among diabetics and nondiabetics are consistent with high rates of nondiabetic kidney disease among Zuni Indians with and without diabetes.

Periodontal disease and mortality in type 2 diabetes

OBJECTIVE

Periodontal disease may contribute to the increased mortality associated with diabetes.

RESEARCH DESIGN AND METHODS

In a prospective longitudinal study of 628 subjects aged > or =35 years, we examined the effect of periodontal disease on overall and cardiovascular disease mortality in Pima Indians with type 2 diabetes. Periodontal abnormality was classified as no or mild, moderate, and severe, based on panoramic radiographs and clinical dental examinations.

RESULTS

During a median follow-up of 11 years (range 0.3-16), 204 subjects died. The age- and sex-adjusted death rates for all natural causes expressed as the number of deaths per 1,000 person-years of follow-up were 3.7 (95% CI 0.7-6.6) for no or mild periodontal disease, 19.6 (10.7-28.5) for moderate periodontal disease, and 28.4 (22.3-34.6) for severe periodontal disease. Periodontal disease predicted deaths from ischemic heart disease (IHD) (P trend = 0.04) and diabetic nephropathy (P trend < 0.01). Death rates from other causes were not associated with periodontal disease. After adjustment for age, sex, duration of diabetes, HbA1c, macroalbuminuria, BMI, serum cholesterol concentration, hypertension, electrocardiographic abnormalities, and current smoking in a proportional hazards model, subjects with severe periodontal disease had 3.2 times the risk (95% CI 1.1-9.3) of cardiorenal mortality (IHD and diabetic nephropathy combined) compared with the reference group (no or mild periodontal disease and moderate periodontal disease combined).

CONCLUSIONS

Periodontal disease is a strong predictor of mortality from IHD and diabetic nephropathy in Pima Indians with type 2 diabetes. The effect of periodontal disease is in addition to the effects of traditional risk factors for these diseases.

IGT with fasting hyperglycemia is more strongly associated with microalbuminuria than IGT without fasting hyperglycemia

Previous studies have established that impaired glucose tolerance (IGT) patients with fasting hyperglycemia (IGT/FH: fasting plasma glucose (FPG) level 6.1-7.0 mmol/l and 2 h PG level of 7.8-11.1 mmol/l) exhibit higher insulin resistance than those with isolated IGT (FPG level <6.1 mmol/l and 2 h PG level of 7.8-11.1 mmol/l), but the association with microalbuminuria has not been determined. Here, we evaluate the prevalence of microalbuminuria in non-diabetic Japanese males 20-70 years of age. The subjects were classified into four groups based on the results of OGTT: normal glucose tolerance (NGT: n=71), impaired fasting glucose (IFG: n=24), isolated IGT (n=36), and IGT/FH (n=23). A urinary albumin-to-creatinine ratio (ACR) from 30 to 300 microg/mg creatinine was counted as microalbuminuria. The prevalence of microalbuminuria was higher in subjects with IGT/FH than in subjects with isolated IGT (26% versus 14%). Logistic regression analysis showed microalbuminuria to be more significantly associated with IGT/FH (OR=3.82, 95% CI 1.09-13.36) than with isolated IGT (OR=1.75, 95% CI 0.50-6.17). While insulin resistance (HOMA-IR) in isolated IGT was not significantly different from that in NGT, insulin resistance in IGT/FH was significantly higher (P<0.01). Regression analysis of ACR in IGT showed a significant correlation with insulin resistance (P=0.012). Accordingly, microalbuminuria is more strongly associated with IGT/FH than with isolated IGT, most likely due to the higher insulin resistance.

Diabetes and renal disease in veterans

OBJECTIVE

To describe the frequency and sequelae of diabetic renal disease in veterans who receive health care from the Veterans Administration (VA).

RESEARCH DESIGN AND METHODS

Veterans with a diagnosis of diabetes, diabetic nephropathy, other kidney diseases, and end-stage renal disease (ESRD) were identified by diagnosis codes from national VA databases for FY1998. Data were obtained and analyzed for prevalence of renal disease, comorbid conditions, and 1-year mortality.

RESULTS

A total of 44,671 (10.7%) of the 415,910 veterans with diabetes had a concomitant diagnosis of any renal disease. The average age was 67 years; 98% were male and 60% were white. The prevalence of diabetic nephropathy was 6.0% (n = 25,263). ESRD secondary to diabetes was present in 4.2% (17,636) of subjects. The age-standardized prevalence of diabetes and any renal disease was 72.6/1,000 persons and differed by race (white 76.1/1,000, black 103.4/1,000 persons). Diabetes-associated ESRD prevalence was higher among black versus white veterans and male versus female veterans. One-year age-standardized mortality was 10.7%.

CONCLUSIONS

Nephropathy is prevalent in veterans with diabetes. Greater mortality is observed among those with renal disease compared with those without renal disease. Additional surveillance is needed to identify persons likely to progress to diabetic nephropathy and to plan for appropriate and timely health care for these individuals.

Epidemic of diabetic and nondiabetic renal disease among the Zuni Indians: the Zuni Kidney Project

There is an epidemic of renal disease among the Zuni Indians. The prevalence of end-stage renal disease among the Zuni Indians is 18.4-fold and 7.4-fold higher than among European Americans and American Indians/Alaskan Natives, respectively. In contrast to other American Indian tribes, nondiabetic renal disease accounts for a significant percent of the renal disease burden among the Zuni Indians. To explore this hypothesis, a community epidemiologic study of the Zuni Pueblo was conducted. A questionnaire was administered, blood and urine samples were collected, and BP, height, and weight were measured. Neighborhood household clusters were used as the sampling frame to maximize ascertainment and minimize bias. Age and gender distributions in the sample (n = 1483) were similar to those of the eligible Zuni population (n = 9228). The prevalence, age-adjusted and gender-adjusted to the Zuni population, of incipient (0.03 < or = UACR < 0.3) albuminuria (IA) (15.0% [95% confidence interval, 13.1 to 16.9%]), and overt (UACR > or = 0.3) albuminuria (OA) (4.7% [3.6 to 5.8%]) was high. The prevalence estimates for IA and OA were higher among diabetic participants (IA: 33.6% [27.6 to 39.7%]; OA: 18.7% [13.7 to 23.7%]) than nondiabetic participants (IA: 10.8% [9.0 to 12.6%]; OA: 1.8% [1.0 to 2.5%]). However, there were more nondiabetic participants; therefore, they comprised 58.0% [51.4 to 64.6%] and 30.9% [20.0 to 41.7%] of participants with IA and OA, respectively. In contrast to most other American Indian tribes, nondiabetic renal disease contributes significantly to the overall burden of renal disease among the Zuni Indians.

Avaliação quanto à presença de microalbuminúria e hiperfiltração glomerular no estágio de tolerância à glicose diminuída

Na fase de tolerância à glicose diminuída (TGD) já estão presentes vários distúrbios metabólicos característicos do diabetes mellitus tipo 2 e fatores de risco que predispõem à vasculopatia. Nosso objetivo foi o de verificar se indivíduos de nossa população, com TGD e normotensos, apresentam elevação da excreção urinária de albumina (EUA) e da depuração de creatinina (D Cr). Teste oral de tolerância à glicose padrão com dosagem de insulina foi realizado, classificando os participantes em dois grupos: com TGD e com tolerância à glicose normal (TGN). Urina do período noturno foi utilizada para a determinação da EUA (imunoturbidimetria) e da D Cr. Os dois grupos não diferiram quanto à EUA e à D Cr. A freqüência de microalbuminúria foi de 21,1 e 3,3%, respectivamente, para os grupos com TGD e TGN (NS). Concluímos que, nesta amostra da população brasileira, indivíduos com TGD, normotensos e com resistência à insulina não apresentaram microalbuminúria e hiperfiltração glomerular.

Longitudinal association of glycemia and microalbuminuria: the Framingham Offspring Study

OBJECTIVE

To assess current and long-term associations of glycemia with microalbuminuria, a marker of generalized endothelial injury.

RESEARCH DESIGN AND METHODS

We measured clinical characteristics, fasting plasma glucose, and the urinary albumin-to-creatinine ratio (UACR) in 1,311 men and 1,518 women attending the sixth examination cycle (1995-1998) of the Framingham Offspring Study. After excluding participants with diabetes or cardiovascular disease (CVD) at the baseline examination (1971-1974), we used fasting glucose measured at baseline, examination 6, and at least two additional examinations from 1974 to 1995 in regression models to predict risk for microalbuminuria (UACR > or = 30 mg/g) associated with baseline, current, and 24-year time-integrated glycemia.

RESULTS

Microalbuminuria was present in 9.5% of men and 13.4% of women. Among men, age-adjusted odds ratios (95% CI) for microalbuminuria associated with each 0.28 mmol/l (5 mg/dl) increase in baseline, current, and time-integrated glucose levels were 1.12 (1.00-1.16), 1.08 (1.05-1.10), and 1.16 (1.11-1.21), respectively. These effects persisted after adjustment for systolic blood pressure and other confounders. Higher glucose levels also predicted incident diabetes and CVD. Mean time-integrated glucose levels were highest among men who developed both CVD and microalbuminuria (SE 6.82 +/- 0.16 mmol/l), intermediate among men with either condition (6.03 +/- 0.65 mmol/l), and lowest among men with neither condition (5.49 +/- 0.02 mmol/l; P < 0.001 for all pairwise comparisons). We observed similar associations in women.

CONCLUSIONS

Long-term hyperglycemia and subdiabetic glycemia increase risk for microalbuminuria. Microalbuminuria, type 2 diabetes, and CVD seem to arise together over the course of decades, consistent with the hypothesis that they share a common antecedent.

Microalbuminuria in the US population: third National Health and Nutrition Examination Survey

Microalbuminuria (MA) is associated with adverse health outcomes in diabetic and hypertensive adults. The prevalence and clinical significance of MA in nondiabetic populations is less clear. The purpose of this study was to generate national estimates of the prevalence of MA in the US population. Untimed urinary albumin concentrations (UACs) and creatinine concentrations were evaluated in a nationally representative sample of 22,244 participants aged 6 years and older. Persons with hematuria and menstruating or pregnant women were excluded from analysis. The percent prevalence of clinical proteinuria (UAC > or = 300 mg/L) was similar for males and females. However, the prevalence of MA (urinary albumin-creatinine ratio [ACR], 30 to 299 mg/g) was significantly lower in males (6.1%) compared with females (9.7%). MA prevalence was greater in children than young adults and increased continuously starting at 40 years of age. MA prevalence was greater in non-Hispanic blacks and Mexican Americans aged 40 to 79 years compared with similar-aged non-Hispanic whites. MA prevalence was 28.8% in persons with previously diagnosed diabetes, 16.0% in those with hypertension, and 5.1% in those without diabetes, hypertension, cardiovascular disease, or elevated serum creatinine levels. In adults aged 40+ years, after excluding persons with clinical proteinuria, albuminuria (defined as ACR > or = 30 mg/g) was independently associated with older age, non-Hispanic black and Mexican American ethnicity, diabetes, hypertension, and elevated serum creatinine concentration. MA is common, even among persons without diabetes or hypertension. Age, sex, race/ethnicity, and concomitant disease contribute to the variability of MA prevalence estimates.

Microalbuminuria, an integrated marker of cardiovascular risk in essential hypertension

This paper reviews the existing epidemiological and clinical evidence about the relationships of non-diabetic microalbuminuria with cardiovascular risk factors such as elevated blood pressure (BP), systolic particularly, cardiac hypertrophy, adverse metabolic status, smoking habits, elevated angiotensin II levels, endothelial dysfunction, acute and perhaps subclinical inflammation. Because of that unique property of reflecting the influence of so many clinically relevant parameters, microalbuminuria may legitimately be defined as an integrated marker of cardiovascular risk, an unique profile among the several prognostic predictors available to stratify risk in hypertensive patients. Recent cohort studies also showed associations with cardiovascular morbidity and mortality independently from conventional atherogenic factors. This behaviour, whose understanding still needs further elucidation, suggests to measure albuminuria and to screen patients at a higher absolute risk in whom preventive treatment is expected to be more beneficial than in those with a lower absolute risk.

Genetics of diabetic nephropathy in the Pima Indians

Diabetic nephropathy is the leading cause of renal failure in industrialized countries. There is strong evidence that diabetic nephropathy is influenced by genetic factors. Studies in the Pima Indians as well as in other populations demonstrate that diabetic nephropathy aggregates in families. The hypothesis that the familial aggregation reflects the effect of a major gene was formally tested by segregation analysis of diabetic nephropathy in Pima Indians with type 2 diabetes. The segregation analysis provided strong evidence for a major genetic effect on the prevalence of diabetic nephropathy; this suggests that some of the genetic determinants of diabetic nephropathy may have effects of sufficient magnitude to be detected by linkage analysis. Therefore, we analyzed data from a genome-wide scan to identify susceptibility loci for nephropathy in diabetic Pima Indians. Analyses conducted by both parametric (model-based) and nonparametric methods revealed tentative evidence for nephropathy susceptibility loci on chromosomes 3q, 7q, 18q, and 20p.

Prevalence and risk factors of microalbuminuria in a cohort of African-American women with gestational diabetes

OBJECTIVE

To study the prevalence of microalbuminuria (MA) in African-American women with a history of gestational diabetes (GDM) who are at high risk for insulin resistance and renal dysfunction and to study MA's relation to insulin resistance, type 2 diabetes, and hypertension.

RESEARCH DESIGN AND METHODS

MA was assessed using 24-h, timed, and/or random urine samples in a cross-sectional sample (n = 289) from a cohort of African-American women with a history of GDM and followed for a median of 11 years (range 3.0-18.4) since their diabetic pregnancy. Subjects with a urine albumin excretion rate of 30-300 g/24 h or 30-300 microg/mg creatinine in a random sample were classified as having MA if two of three samples over a 3- to 6-month period were positive. These women were evaluated for family history of diabetes, smoking and alcohol use, BMI, diabetes, hypertension, and lipid abnormalities. Insulin sensitivity was determined using the homeostasis model assessment (HOMA) estimates, which used fasting insulin and glucose measurements obtained at the same time as the MA urine sample.

RESULTS

At MA assessment, the women ranged in age from 22 to 57 years, with a median of 39 years. The overall prevalence of MA was 20%; 36% in those with diabetes. Those women with MA had higher rates of diabetes (63.8 vs. 28.6%, odds ratio [OR] = 4.4, P < 0.05), hypertension (82.8 vs. 42.9%, OR = 6.4, P < 0.05), and family history of diabetes (85.7 vs. 61.7%, OR = 3.7, P < 0.05). The proportion of subjects with MA with a family history of hypertension was nonsignificantly increased (92.9 vs. 82.4%). Subjects with MA were more obese (BMI 37.2 +/- 8.9 vs. 34.4 +/- 8.6 kg/m(2)) and had higher levels of HbA(1c) (8.8 +/- 3.3 vs. 6.6 +/- 1.8%, P < 0.001) and systolic (144.3 +/- 25.9 vs. 122.8 +/- 17.2 mmHg, P < 0.0001) and diastolic (95.1 +/- 15.4 vs. 82.5 +/- 11.9 mmHg, P < 0.0001) blood pressures. Lipid fractions were similar in those with and without MA. Although fasting glucose was much higher in subjects with MA (10.3 +/- 5.8 vs. 7.1 +/- 4.2 mmol/l, P = 0.0002), insulin levels were not significantly higher in subjects with MA (17.4 +/- 21.2 vs. 15.2 +/- 12.4 pmol/l). Insulin sensitivity, as measured using log HOMA, was similar (1.5 +/- 0.6 vs. 1.6 +/- 0.6) in women with and without MA, respectively. Multivariable logistic regression analyses indicated that HbA(1c), OR = 1.16 (1.07, 1.27), and systolic blood pressure, OR = 1.27 (1.14, 1.41), were independent risk factors for MA. In those with diabetes, the subjects with MA had higher rates of hypertension-83.8 vs. 56.1%, OR = 4.1 (1.5, 11.10)-which was reflected by their higher systolic and diastolic blood pressures, 146.1 mmHg (P = 0.001) and 94.8 mmHg (P = 0.002), respectively, and lower levels of VLDL (0.45 +/- 0.22 vs. 0.61 +/- 0.33 mmol/l, P = 0.021). In the multivariable analyses of those with diabetes, the two independent risk factors for MA were similar: HbA(1c), OR = 1.13 (1.01, 1.28), and systolic blood pressure, OR = 1.21 (1.04, 1.41).

CONCLUSIONS

African-American women with a history of GDM have one of the highest rates for MA. Presence of MA was not associated with insulin resistance but was significantly independently associated with HbA(1c) levels and hypertension. These results, taken in context of the literature, suggest that hypertension and glucose intolerance, in part, influence MA through different mechanisms. Because of the high prevalence of MA in this population and MA's relation to all-cause and cardiovascular mortality, screening for MA should be considered.

Insulin resistance precedes the appearance of albuminuria in non-diabetic subjects: 6 years follow up study

Microalbuminuria is a marker of increased risk of cardiovascular mortality in type 1 and type 2 diabetes, and in non-diabetic subjects. Little is known about the association between prospective changes of microalbuminuria and the risk factors of atherosclerosis, or gene polymorphism in non-diabetic subjects. We conducted a 6-year prospective study of risk factors for progression of albuminuria in non-diabetic subjects. The participants were 116 non-diabetic subjects who consecutively underwent medical examinations for Japanese-Americans living in Hawaii. In the baseline examination in 1992, normoalbuminuria was found in all subjects. After 6 years, 101 subjects remained normoalbuminuria (non-progressors), 15 subjects changing from normoalbuminuria to microalbuminuria or proteinuria and were defined as progressors. In progressors, compared with non-progressors, the fasting insulin level and HOMA-R were significantly higher at 3 years follow-up, and the systolic and diastolic pressure and Sigma insulin level were significantly higher at 6 years follow-up. Insulin resistance appeared earlier than the appearance of hypertension and albuminuria. In progressors, there was no significant correlation with angiotensin-converting enzyme (ACE) genotype or angiotensinogen (AGT) genotype compared with non-progressors. Therefore, the appearance of insulin resistance should be regarded as a remarkable mediator of albuminuria.

Prevalence of microalbuminuria in type 2 diabetes mellitus at a diabetes centre in southern India

OBJECTIVE

The aim of this study was to determine the prevalence and risk factors for microalbuminuria among south Indian type 2 diabetic patients attending a diabetes centre.

METHODS

One thousand four hundred and twenty five type 2 diabetic patients attending a diabetes centre in south India were recruited for the study. Urinary albumin concentration was measured by immunoturbodimetric assay. Microalbuminuria was diagnosed if the urinary albumin excretion was >30 mg/g of creatinine.

RESULTS

Overall prevalence of microalbuminuria was 36.3% (95% confidence interval 33.8 to 38.9). The prevalence of microalbuminuria increased with the increase in duration of diabetes. Multivariate regression analysis revealed age, diastolic blood pressure, glycated haemoglobin, fasting plasma glucose, and duration of diabetes to be associated with microalbuminuria.

CONCLUSION

The overall prevalence of microalbuminuria in this south Indian clinic population and its risk factors are similar to that reported in Europeans.

Glomerular permselectivity at the onset of nephropathy in type 2 diabetes mellitus

The development of microalbuminuria in individuals with type 2 diabetes mellitus is associated with a 10-fold increase in the risk of progression to overt nephropathy and eventual end-stage renal failure. The present study reports long-term (up to 8 yr) follow-up of 43 Pima Indians with type 2 diabetes detected on screening to have microalbuminuria. The natural history of albuminuria in these individuals included progression to overt proteinuria (urinary albumin excretion > or = 300 mg/d) in half of the participants by 7 yr of follow-up. The size selectivity of the glomerular barrier was also investigated using dextran sieving and pore theory. Whereas a comparison group of macroalbuminuric Pima Indians had an excess of large pores that served as a macromolecular "shunt," individuals with microalbuminuria had a shunt size no different from long-term diabetic, normoalbuminuric control subjects. An abrupt transition from little or no relationship to a highly significant and positive relationship between increasing albuminuria and shunt size occurred at an albumin-to-creatinine ratio of approximately 3000 mg/g. Shunt size in macroalbuminuric individuals correlated with the extent of foot process broadening. Podocyte foot processes in microalbuminuric participants were not different from those in control subjects. In conclusion, although microalbuminuria in type 2 diabetic Pima Indians often heralds progressive glomerular injury, it is not the result of defects in the size permselectivity of the glomerular barrier but rather of changes in either glomerular charge selectivity or tubular handling of filtered proteins or of a combination of these two factors.

Risk factors for microalbuminuria in black americans with newly diagnosed type 2 diabetes

We conducted a cross-sectional analysis to describe the prevalence of and risk factors for microalbuminuria among blacks with newly diagnosed type 2 diabetes. Black adults with diagnosed type 2 diabetes mellitus of 2 years' duration or less who presented for care to the Grady Diabetes Clinic (Atlanta, GA) between January 1, 1994, and December 31, 1996, were eligible (n = 1,167). Information obtained at the initial visit included age; sex; body mass index (BMI); serum total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, C-peptide, serum creatinine, and hemoglobin A1c (HbA(1c)) levels; and seated systolic and diastolic blood pressures. Outcome was urine albumin-creatinine (Alb/Cr) ratio at the initial visit. Alb/Cr ratios were categorized as normal (Alb/Cr <25 microgram/mg), microalbuminuric (Alb/Cr, 25 to 250 microgram/mg), and macroalbuminuric (Alb/Cr >250 microgram/mg). Patients with macroalbuminuria or creatinine levels of 2 mg/dL or greater were excluded. We used multiple linear regression to assess the joint association between HbA(1c) level, mean arterial pressure (MAP), and log-transformed Alb/Cr, controlling for other covariates. Of 1,044 patients studied, macroalbuminuria was present in 3.8%, and microalbuminuria, in 23.4%. Alb/Cr was independently associated with increased HbA(1c) level (P = 0.0070), MAP (P = 0.0001), BMI (P = 0.0156), log-transformed triglyceride levels (P = 0.0031), C-peptide level of 6.5 ng/mL or greater (P = 0.0007), serum creatinine level (P: = 0.0068), and male sex (P = 0.0220). The relationship between HbA(1c) level and microalbuminuria was stronger in patients with lower BMIs. Microalbuminuria prevalence was high in this population of urban blacks with newly diagnosed type 2 diabetes. Risk factors associated with increased Alb/Cr included male sex, poor glycemic control, endogenous hyperinsulinemia, high blood pressure, elevated triglyceride levels, and obesity.

Evolution of incipient nephropathy in type 2 diabetes mellitus

BACKGROUND

We examined the course of glomerular injury in 12 Pima Indians with long-standing (>8 years) type 2 diabetes mellitus, normal serum creatinine, and microalbuminuria. They were compared with a group of 10 Pima Indians in Arizona with new-onset (<5 years) type 2 diabetes, normal renal function, and normoalbuminuria (<30 mg albumin/g creatinine on random urine specimens).

METHODS

A combination of physiological and morphological techniques was used to evaluate glomerular function and structure serially on two occasions separated by a 48-month interval. Clearances of iothalamate and p-aminohippuric acid were used to determine glomerular filtration rate (GFR) and renal plasma flow, respectively. Afferent oncotic pressure was determined by membrane osmometry. The single nephron ultrafiltration coefficient (Kf) was determined by morphometric analysis of glomeruli and mathematical modeling.

RESULTS

The urinary albumin-to-creatinine ratio (median + range) increased from 84 (28 to 415) to 260 (31 to 2232) mg/g between the two examinations (P = 0.01), and 6 of 12 patients advanced from incipient (ratio = 30 to 299 mg/g) to overt nephropathy (>/=300 mg/g). A 17% decline in GFR between the two examinations from 186 +/- 41 to 155 +/- 50 mL/min (mean +/- SD; P = 0.06) was accompanied by a 17% decline in renal plasma flow (P = 0.003) and a 6% increase in plasma oncotic pressure (P = 0.02). Computed glomerular hydraulic permeability was depressed by 13% below control values at both examinations, a result of a widened basement membrane and a reduction in frequency of epithelial filtration slits. The filtration surface area declined significantly, however, from 6.96 +/- 2.53 to 5.51 +/- 1.62 x 105 mm2 (P = 0.01), a change that was accompanied by a significant decline in the number of mesangial cells (P = 0.001), endothelial cells (P = 0.038), and podocytes (P = 0.0005). These changes lowered single nephron Kf by 20% from 16.5 +/- 6.0 to 13.2 +/- 3.6 nL/(minutes + mm Hg) between the two examinations (P = 0.02). Multiple linear regression analysis revealed that among the determinants of GFR, only the change in single nephron Kf was related to the corresponding change in GFR.

CONCLUSION

We conclude that a reduction in Kf is the major determinant of a decline in GFR from an elevated toward a normal range as nephropathy in type 2 diabetes advances from an incipient to an overt stage.

Vasoconstriction to endothelin-1 is blunted in non-insulin-dependent diabetes: a dose-response study

The haemodynamic hypothesis for the pathogenesis of diabetic microangiopathy argues that an initial increase in microvascular blood flow leads to microvascular sclerosis and disturbed autoregulation. Endothelin-1 (ET-1) is an endothelium-derived vasoconstrictor peptide that contributes to basal vascular tone. Impairment of the vasoconstrictor response to ET-1 could result in hyperperfusion and subsequent microvascular damage. The purpose of this study was to determine whether vascular responses to ET-1 are impaired in patients with non-insulin-dependent diabetes mellitus (type 2 diabetes). Ten patients with type 2 diabetes and nine control subjects underwent brachial artery cannulation. Forearm blood flow was measured using strain-gauge venous occlusion plethysmography. ET-1 in three doses of 5, 10, and 20 pmol/min and 0.9% saline placebo was infused in a balanced double-blind randomised manner. Vascular smooth muscle function also was assessed using sodium nitroprusside. Control subjects showed vasoconstriction to ET-1 of 5 (p < 0.05), 10 (p < 0.05), and 20 pmol/min (p < 0.01). In the diabetic group, there was no significant response to ET-1 at 5 pmol/min (p > 0.05); however, significant vasoconstriction developed at 10 and 20 pmol/min (p < 0.01). There was a significant difference in response to ET-1 at 5 pmol/min between the diabetic and control groups (p < 0.05). Responses to sodium nitroprusside were similar in both groups (p > 0.05). Patients with type 2 diabetes have a blunted vasoconstrictor response to ET-1 despite preserved vascular smooth muscle function.

Diabetic microangiopathic complications in young Chinese diabetic patients: a clinic-based cross-sectional study

Microangiopathic complications are major causes of morbidity and mortality in diabetic patients. We studied 150 consecutive young Chinese diabetic subjects attending the Prince of Wales Hospital Diabetes Center on their presence of diabetic microangiopathic complications and the relationships with other risk factors. All patients with aged younger than 40 years and had an age of onset of disease at younger than 35 years. Their known duration of diabetes was 57.2 +/- 5.0 months. Of these 150 patients, 50 (33.3%) had microangiopathic complications, 34 (22.7%) had albuminuria, 11 (7. 3%) had peripheral neuropathy, and 21 (14%) had retinopathy. Using multiple logistic regression analysis, albuminuria was independently associated with body-mass index and systolic blood pressure, peripheral neuropathy was associated with fasting plasma glucose and lower high-density lipoprotein cholesterol, and retinopathy was associated with duration of disease and fasting plasma glucose. In conclusion, there were high percentages of microangiopathic complications, particularly albuminuria, in our young Chinese diabetic patients. Obesity, high blood pressure, and poor glycemic control are important for these complications.