Translating HbA1c measurements into estimated average glucose values in pregnant women with diabetes.

AIMS/HYPOTHESIS: This study aimed to examine the relationship between average glucose levels, assessed by continuous glucose monitoring (CGM), and HbA1c levels in pregnant women with diabetes to determine whether calculations of standard estimated average glucose (eAG) levels from HbA1c measurements are applicable to pregnant women with diabetes. METHODS: CGM data from 117 pregnant women (89 women with type 1 diabetes; 28 women with type 2 diabetes) were analysed. Average glucose levels were calculated from 5-7 day CGM profiles (mean 1275 glucose values per profile) and paired with a corresponding (±1 week) HbA1c measure. In total, 688 average glucose-HbA1c pairs were obtained across pregnancy (mean six pairs per participant). Average glucose level was used as the dependent variable in a regression model. Covariates were gestational week, study centre and HbA1c. RESULTS: There was a strong association between HbA1c and average glucose values in pregnancy (coefficient 0.67 [95% CI 0.57, 0.78]), i.e. a 1% (11 mmol/mol) difference in HbA1c corresponded to a 0.67 mmol/l difference in average glucose. The random effects model that included gestational week as a curvilinear (quadratic) covariate fitted best, allowing calculation of a pregnancy-specific eAG (PeAG). This showed that an HbA1c of 8.0% (64 mmol/mol) gave a PeAG of 7.4-7.7 mmol/l (depending on gestational week), compared with a standard eAG of 10.2 mmol/l. The PeAG associated with maintaining an HbA1c level of 6.0% (42 mmol/mol) during pregnancy was between 6.4 and 6.7 mmol/l, depending on gestational week. CONCLUSIONS/INTERPRETATION: The HbA1c-average glucose relationship is altered by pregnancy. Routinely generated standard eAG values do not account for this difference between pregnant and non-pregnant individuals and, thus, should not be used during pregnancy. Instead, the PeAG values deduced in the current study are recommended for antenatal clinical care.

Urinary proteomics predict onset of microalbuminuria in normoalbuminuric type 2 diabetic patients, a sub-study of the DIRECT-Protect 2 study.

BACKGROUND: Early prevention of diabetic nephropathy is not successful as early interventions have shown conflicting results, partly because of a lack of early and precise indicators of disease development. Urinary proteomics has shown promise in this regard and could identify those at high risk who might benefit from treatment. In this study we investigate its utility in a large type 2 diabetic cohort with normoalbuminuria. METHODS: We performed a post hoc analysis in the Diabetic Retinopathy Candesartan Trials (DIRECT-Protect 2 study), a multi centric randomized clinical controlled trial. Patients were allocated to candesartan or placebo, with the aim of slowing the progression of retinopathy. The secondary endpoint was development of persistent microalbuminuria (three of four samples). We used a previously defined chronic kidney disease risk score based on proteomic measurement of 273 urinary peptides (CKD273-classifier). A Cox regression model for the progression of albuminuria was developed and evaluated with integrated discrimination improvement (IDI), continuous net reclassification index (cNRI) and receiver operating characteristic curve statistics. RESULTS: Seven hundred and thirty-seven patients were analysed and 89 developed persistent microalbuminuria (12%) with a mean follow-up of 4.1 years. At baseline the CKD273-classifier predicted development of microalbuminuria during follow-up, independent of treatment (candesartan/placebo), age, gender, systolic blood pressure, urine albumin excretion rate, estimated glomerular filtration rate, HbA1c and diabetes duration, with hazard ratio 2.5 [95% confidence interval (CI) 1.4-4.3; P = 0.002] and area under the curve 0.79 (95% CI 0.75-0.84; P < 0.0001). The CKD273-classifier improved the risk prediction (relative IDI 14%, P = 0.002; cNRI 0.10, P = 0.043). CONCLUSIONS: In this cohort of patients with type 2 diabetes and normoalbuminuria from a large intervention study, the CKD273-classifier was an independent predictor of microalbuminuria. This may help identify high-risk normoalbuminuric patients for preventive strategies for diabetic nephropathy.

Laboratory Assessment of Diabetic Kidney Disease.

IN BRIEF Regardless of etiology, chronic kidney disease (CKD) is identified by two laboratory tests: 1) estimated glomerular filtration rate (eGFR), a measure of kidney function, and 2) urine albumin-to-creatinine ratio (UACR), a measure of kidney damage. It is crucial for all health professionals to understand the significance and limitations of these tests to appropriately identify CKD patients, guide therapy, and determine prognosis. This article provides information that will enable diabetes educators and other clinicians to properly interpret eGFR and UACR laboratory results in the identification and management of CKD.

Diabetic kidney disease: a report from an ADA Consensus Conference.

The incidence and prevalence of diabetes mellitus have grown significantly throughout the world, due primarily to the increase in type 2 diabetes. This overall increase in the number of people with diabetes has had a major impact on development of diabetic kidney disease (DKD), one of the most frequent complications of both types of diabetes. DKD is the leading cause of end-stage renal disease (ESRD), accounting for approximately 50% of cases in the developed world. Although incidence rates for ESRD attributable to DKD have recently stabilized, these rates continue to rise in high-risk groups such as middle-aged African Americans, Native Americans, and Hispanics. The costs of care for people with DKD are extraordinarily high. In the Medicare population alone, DKD-related expenditures among this mostly older group were nearly $25 billion in 2011. Due to the high human and societal costs, the Consensus Conference on Chronic Kidney Disease and Diabetes was convened by the American Diabetes Association in collaboration with the American Society of Nephrology and the National Kidney Foundation to appraise issues regarding patient management, highlighting current practices and new directions. Major topic areas in DKD included (1) identification and monitoring, (2) cardiovascular disease and management of dyslipidemia, (3) hypertension and use of renin-angiotensin-aldosterone system blockade and mineralocorticoid receptor blockade, (4) glycemia measurement, hypoglycemia, and drug therapies, (5) nutrition and general care in advanced-stage chronic kidney disease, (6) children and adolescents, and (7) multidisciplinary approaches and medical home models for health care delivery. This current state summary and research recommendations are designed to guide advances in care and the generation of new knowledge that will meaningfully improve life for people with DKD.

Resolving the Gestational Diabetes Diagnosis Conundrum: The Need for a Randomized Controlled Trial of Treatment.

The diagnosis of and criteria for gestational diabetes mellitus (GDM) continue to divide the scientific and medical community, both between and within countries. Many argue for universal adoption of the International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criteria and feel that further clinical trials are unjustified and even unethical. However, there are concerns about the large increase in number of women who would be diagnosed with GDM using these criteria and the subsequent impact on health care resources and the individual. This Perspective reviews the origins of the IADPSG consensus and points out some of its less well-known limitations, particularly with respect to identifying women at risk for an adverse pregnancy outcome. It also questions the clinical and cost-effectiveness data often cited to support the IADPSG glycemic thresholds. We present the argument that adoption of diagnostic criteria defining GDM should be based on response to treatment at different diagnostic thresholds of maternal glycemia. This will likely require an international multicenter trial of treatment.

Peroxisome proliferator-activated receptor-γ agonist rosiglitazone prevents albuminuria but not glomerulosclerosis in experimental diabetes.

BACKGROUNDS/AIMS: Renal inflammation and nephrin downregulation contribute to albuminuria in diabetes. We studied, in streptozotocin-induced diabetic rats, the effect of rosiglitazone (RSG), a peroxisome proliferator-activated receptor-γ agonist, on renal macrophage infiltration, MCP1, and nephrin expression in relation to albuminuria. METHODS: We investigated control and diabetic rats treated or untreated with RSG. Animals were sacrificed at 1, 3, and 9 months. Renal MCP1 and nephrin expression were studied by immunoblotting, renal macrophage infiltration by immunohistochemistry, and albuminuria by ELISA. Electron microscopy was used to assess glomerular ultrastructural morphology. In vitro experiments were conducted in isolated cultured rat glomeruli. RESULTS: Glycaemic control was similar in diabetic rats treated and untreated with RSG, and blood pressure was comparable in all groups. RSG prevented diabetes-induced albuminuria at 9 months, and renal macrophage infiltration and MCP1 upregulation at 3 and 9 months. Diabetes-mediated nephrin downregulation was abolished by RSG. Diabetes-induced glomerulosclerosis, glomerular basement membrane thickening, and foot process fusion were not affected by RSG. In isolated glomeruli, MCP1 directly induced nephrin downregulation and this was prevented by RSG. RSG had no effect on nephrin expression. CONCLUSION: RSG prevents albuminuria and nephrin downregulation in experimental diabetes independently of glycaemic and blood pressure control. This effect likely occurs via correction of diabetes-induced inflammatory processes.

Prevalence of atubular glomeruli in type 2 diabetic patients with nephropathy.

BACKGROUND: Atubular glomeruli have been identified in a number of chronic renal diseases and have been linked to declining renal function. In type 1 diabetes they are present predominantly in proteinuric patients. We investigated the prevalence of atubular glomeruli in type 2 diabetes and their relationship to renal function. METHODS: Renal biopsies from 12 type 2 diabetic patients with nephropathy were processed for light and electron microscopy and analysed using standard stereological techniques. Abnormalities at the glomerular tubular junction were quantified using an index of junctional atrophy (IJA). RESULTS: There was no relationship between the degree of proteinuria and the presence of atubular glomeruli or atrophic tubules. Creatinine clearance correlated with the IJA (r = -0.70, P = 0.011), percent sclerosed glomeruli (r = -0.59, P = 0.027) and interstitial volume fraction (r = -0.54, P = 0.037). The IJA also correlated with foot process width and volume fraction interstitium (r = 0.58, P = 0.049 for both). Percent sclerosed glomeruli correlated with mesangial (r = 0.65, P = 0.012) and interstitial (r = 0.69, P = 0.007) volume fractions. CONCLUSIONS: In contrast to type 1 diabetes, atubular glomeruli and atrophic tubules occur in type 2 diabetic patients with low levels of proteinuria; their development may influence the progressive change in GFR. Both glomerular and interstitial damage may lead to the development of atubular glomeruli in type 2 diabetic nephropathy.

Prediction of Chronic Kidney Disease Stage 3 by CKD273, a Urinary Proteomic Biomarker.

INTRODUCTION: CKD273 is a urinary biomarker, which in advanced chronic kidney disease predicts further deterioration. We investigated whether CKD273 can also predict a decline of estimated glomerular filtration rate (eGFR) to <60 ml/min per 1.73 m2. METHODS: In analyses of 2087 individuals from 6 cohorts (46.4% women; 73.5% with diabetes; mean age, 46.1 years; eGFR ≥ 60 ml/min per 1.73 m2, 100%; urinary albumin excretion rate [UAE] ≥20 µg/min, 6.2%), we accounted for cohort, sex, age, mean arterial pressure, diabetes, and eGFR at baseline and expressed associations per 1-SD increment in urinary biomarkers. RESULTS: Over 5 (median) follow-up visits, eGFR decreased more with higher baseline CKD273 than UAE (1.64 vs. 0.82 ml/min per 1.73 m2; P < 0.0001). Over 4.6 years (median), 390 participants experienced a first renal endpoint (eGFR decrease by ≥10 to <60 ml/min per 1.73 m2), and 172 experienced an endpoint sustained over follow-up. The risk of a first and sustained renal endpoint increased with UAE (hazard ratio ≥ 1.23; P ≤ 0.043) and CKD273 (≥ 1.20; P ≤ 0.031). UAE (≥20 µg/min) and CKD273 (≥0.154) thresholds yielded sensitivities of 30% and 33% and specificities of 82% and 83% (P ≤ 0.0001 for difference between UAE and CKD273 in proportion of correctly classified individuals). As continuous markers, CKD273 (P = 0.039), but not UAE (P = 0.065), increased the integrated discrimination improvement, while both UAE and CKD273 improved the net reclassification index (P ≤ 0.0003), except for UAE per threshold (P = 0.086). DISCUSSION: In conclusion, while accounting for baseline eGFR, albuminuria, and covariables, CKD273 adds to the prediction of stage 3 chronic kidney disease, at which point intervention remains an achievable therapeutic target.

Podocyte number in normotensive type 1 diabetic patients with albuminuria.

We estimated glomerular cell number in 50 normotensive type 1 diabetic patients with raised albumin excretion rate (AER) and investigated any change after 3 years in a subgroup of 16 placebo-treated patients. Biopsies from 10 normal kidney donors were used as controls. Mesangial and endothelial cell number was increased in the 50 diabetic patients at the start of the study compared with control subjects. There was no difference in podocyte number. Glomerular volume was increased in diabetic patients, but surface area of glomerular basement membrane (GBM) underlying the podocytes did not differ between groups. AER correlated positively with mesangial cell number in microalbuminuric patients (r = 0.44, P = 0.012) and negatively with podocyte number in proteinuric patients (r = -0.48, P = 0.040). In the 16 placebo-treated patients, glomerular volume increased after 3 years owing to matrix accumulation and increased GBM surface area. Although overall cell number did not differ significantly from baseline, the decrease in podocyte number during follow-up correlated with AER at follow-up (r = -0.72, P = 0.002). In conclusion, cross-sectional analysis of podocyte number in type 1 diabetic patients with raised AER but normal blood pressure shows no significant reduction compared with nondiabetic control subjects. Longitudinal data provide evidence for an association between podocyte loss and AER, but whether cellular changes are a response to, a cause of, or concomitant with the progression of nephropathy remains uncertain.

Diabetic kidney disease: a report from an ADA Consensus Conference.

The incidence and prevalence of diabetes mellitus have grown significantly throughout the world, due primarily to the increase in type 2 diabetes. This overall increase in the number of people with diabetes has had a major impact on development of diabetic kidney disease (DKD), one of the most frequent complications of both types of diabetes. DKD is the leading cause of end-stage renal disease (ESRD), accounting for approximately 50% of cases in the developed world. Although incidence rates for ESRD attributable to DKD have recently stabilized, these rates continue to rise in high-risk groups such as middle-aged African Americans, Native Americans, and Hispanics. The costs of care for people with DKD are extraordinarily high. In the Medicare population alone, DKD-related expenditures among this mostly older group were nearly $25 billion in 2011. Due to the high human and societal costs, the Consensus Conference on Chronic Kidney Disease and Diabetes was convened by the American Diabetes Association in collaboration with the American Society of Nephrology and the National Kidney Foundation to appraise issues regarding patient management, highlighting current practices and new directions. Major topic areas in DKD included 1) identification and monitoring, 2) cardiovascular disease and management of dyslipidemia, 3) hypertension and use of renin-angiotensin-aldosterone system blockade and mineralocorticoid receptor blockade, 4) glycemia measurement, hypoglycemia, and drug therapies, 5) nutrition and general care in advanced-stage chronic kidney disease, 6) children and adolescents, and 7) multidisciplinary approaches and medical home models for health care delivery. This current state summary and research recommendations are designed to guide advances in care and the generation of new knowledge that will meaningfully improve life for people with DKD.

Podocyte-specific expression of angiopoietin-2 causes proteinuria and apoptosis of glomerular endothelia.

Angiopoietin-2 (Ang-2) modulates embryonic vascular differentiation primarily by inhibiting the antiapoptotic effects of Ang-1 on endothelia that express the Tie-2 receptor. Ang-2 is transiently expressed by developing glomeruli but is downregulated with normal maturation. Glomerular Ang-2 expression is, however, markedly upregulated in animal models of diabetic nephropathy and glomerulonephritis, both leading causes of human chronic renal disease, affecting 10% of the world population. It was hypothesized that Ang-2 might have significant roles in the pathobiology of glomerular disease. Mice with inducible podocyte-specific Ang-2 overexpression were generated. When the transgene was induced in adults for up to 10 wk, mice had significant increases in both albuminuria and glomerular endothelial apoptosis, with significant decreases of both vascular endothelial growth factor-A and nephrin proteins, critical for maintenance of glomerular endothelia and filtration barrier functional integrity, respectively. There was, however, no significant change of systemic BP, creatinine clearance, or markers of renal fibrosis, and podocytes appeared structurally intact. In kidneys of young animals in which Ang-2 had been upregulated during organogenesis, increased apoptosis occurred in just-formed glomeruli. In vitro, short-term exposure of isolated wild-type murine glomeruli to exogenous Ang-2 led to decreased levels of vascular endothelial growth factor-A protein. These novel results provide insight into molecular mechanisms underlying proteinuric disorders, highlight potentially complex interactions between subsets of glomerular cells, and emphasize how a vascular growth factor that has critical roles in normal development may be harmful when re-expressed in the context of adult disease.

Type 2 diabetic patients with nephropathy show structural-functional relationships that are similar to type 1 disease.

Glomerular structural-functional relationships were investigated in 21 type 2 diabetic patients with proteinuria. Structural parameters were quantified using both light and electron microscopy and standard stereologic techniques. Data were also available on 14 nondiabetic subjects. Mesangial and matrix volume fractions and glomerular basement membrane (GBM) width were increased in type 2 patients when compared with nondiabetic subjects (mean +/- SD: 0.45 +/- 0.13 versus 0.18 +/- 0.03, P: < 0.001; 0.28 +/- 0.09 versus 0.10 +/- 0.02, P: < 0.001; and 665 +/- 138 versus 361 +/- 51 nm, P: < 0. 001, respectively). An increase in mesangial volume fraction was associated with high levels of proteinuria and low creatinine clearance (r = 0.64, P: = 0.002; r = -0.58, P: = 0.006, respectively). GBM width and mesangial foot process width (FPW(mes)) also correlated with proteinuria (r = 0.58, P: = 0.006; r = 0.60, P: = 0.004, respectively). Volume fraction of interstitium correlated with creatinine clearance (r = -0.58, P: = 0.006). Patients had previously been defined by light microscopy as having either diffuse or nodular glomerulosclerosis; those with nodules had larger mesangial and matrix volume fractions and more proteinuria than those classified as diffuse (mean +/- SD: 0.51 +/- 0.12 versus 0.36 +/- 0.08, P: = 0.007; 0.32 +/- 0.08 versus 0.21 +/- 0.05, P: = 0. 003; median, range: 4.3, 1.1 to 9.6 versus 1.1, 0.9 to 12.7 g/24 h, P: = 0.027). Creatinine clearance did not differ significantly between the groups. Type 2 diabetic patients with proteinuria have established glomerulopathy, which is more advanced in those with nodular glomerulosclerosis. Creatinine clearance correlated with both mesangial and interstitial expansion, whereas proteinuria correlated only with glomerular pathology. These results suggest that type 2 patients with advanced nephropathy have structural-functional relationships similar to type 1, consistent with a common pathogenesis, and strongly support an important role of the tubulointerstitium in the role of renal impairment.

Structural alterations to the podocyte are related to proteinuria in type 2 diabetic patients.

BACKGROUND: The podocyte is believed to play a key role in maintaining the integrity of the glomerular filtration barrier, and damage or loss has been linked to the development of albuminuria. METHODS: Renal biopsies from 16 type 2 diabetic patients with nephropathy and 28 non-diabetic controls were analysed using light and electron microscopy. RESULTS: Podocyte number per glomerulus was significantly lower in the type 2 patients compared with controls [mean (95% confidence interval) 464 (382-546) vs 589 (543-635), P = 0.004]. Mean glomerular volume was significantly increased in diabetic patients compared with controls [5.5 (4.9-6.1) vs 3.1 (2.7-3.5) x 10(6) microm(3), P<0.001], thus the diabetic patients demonstrated an even greater proportional reduction in podocyte density per glomerulus [88 (68-108) vs 201 (182-220)/10(6) microm(3), P<0.001]. Podocyte foot process width on both the filtration surface (FPWgbm) and mesangial surface (FPWmes) was significantly increased compared with controls [796 (708-884) vs 556 (460-908) nm, P = 0.001; 1108 (821-1394) vs 760 (555-1078) nm, P = 0.029, respectively]. There was a significant negative correlation between proteinuria and both podocyte number and podocyte density per glomerulus (r = -0.63, P = 0.009; r = -0.58, P = 0.018, respectively). There was a significant positive correlation between proteinuria and both FPWgbm and FPWmes (r = 0.64, P = 0.008, for both). CONCLUSION: Podocyte loss occurs in type 2 diabetic nephropathy and is related to increasing proteinuria. Whether the accompanying glomerular enlargement and widening of foot processes are a cause of podocyte loss is uncertain. Longitudinal studies are required to determine the sequence of events leading to podocyte loss in diabetic nephropathy.

Estimation of podocyte number: a comparison of methods.

BACKGROUND: The podocyte is the focus of much research into the mechanisms of renal disease progression, and the number of podocytes per glomerulus has thus become a parameter of much interest. When counting podocytes, the actual particle counted is the cell nucleus. The majority of published studies estimating podocyte number have used the method of Weibel and Gomez (1962). This makes assumptions about the shape and size of the cell nuclei and therefore has an inherent bias. In our studies we have used a more recent stereologic method--the disector/fractionator--that makes no assumptions about the shape or size of the cell nuclei and is therefore free of bias. METHODS: We set out to compare the two methods, in both type 1 diabetic patients and normal controls, to determine whether eliminating bias and thus improving accuracy had any effect on the overall results. The Weibel-Gomez method estimates cell number from a single section through the glomerulus, whereas the disector/fractionator requires the glomerulus to be serially sectioned. RESULTS: There was no significant difference between mean values obtained by the two methods, providing that the Weibel-Gomez estimate was performed on electron micrographs. However, the overall variance was high for all groups of patients, independent of the method employed. CONCLUSION: Although the disector/fractionator is the theoretic gold standard method for podocyte number estimation, comparable estimates can be obtained by the Weibel-Gomez method provided they are made from electron micrographs. Thus the technical resources available may determine the choice of method employed. Investigators should be aware of the high degree of variability in the estimate, particularly when trying to detect small changes in podocyte number.