The changing course of diabetic nephropathy: low-density lipoprotein cholesterol and blood pressure correlate with regression of proteinuria

Regression of albuminuria and its association with incident cardiovascular outcomes and mortality in type 1 diabetes: the FinnDiane Study

AIMS/HYPOTHESIS

Our aim was to assess regression of albuminuria and its clinical consequences in type 1 diabetes.

METHODS

The analysis included 3642 participants from the Finnish Diabetic Nephropathy (FinnDiane) Study with a 24 h urine sample and a history of albuminuria available at baseline. A total of 2729 individuals had normal AER, 438 a history of microalbuminuria and 475 a history of macroalbuminuria. Regression was defined as a change from a higher category of albuminuria pre-baseline to a lower category in two out of the three most recent urine samples at baseline. The impact of regression on cardiovascular events (myocardial infarction, stroke, coronary procedure) and mortality was analysed over a follow-up of 14.0 years (interquartile range 11.9-15.9).

RESULTS

In total, 102 (23.3%) individuals with prior microalbuminuria and 111 (23.4%) with prior macroalbuminuria had regressed at baseline. For individuals with normal AER as a reference, the age-adjusted HRs (95% CI) for cardiovascular events were 1.42 (0.75, 2.68) in individuals with regression from microalbuminuria, 2.62 (1.95, 3.54) in individuals with sustained microalbuminuria, 3.15 (2.02, 4.92) in individuals with regression from macroalbuminuria and 5.49 (4.31, 7.00) in individuals with sustained macroalbuminuria. Furthermore, for all-cause and cardiovascular mortality rates, HRs in regressed individuals were comparable with those with sustained renal status at the achieved level (i.e. those who did not regress but remained at the most advanced level of albuminuria noted pre-baseline).

CONCLUSIONS/INTERPRETATION

Progression of diabetic nephropathy confers an increased risk for cardiovascular disease and premature death. Notably, regression reduces the risk to the same level as for those who did not progress.

The effects of the water-extraction of Astragali Radix and Lycopi herba on the Pathway of TGF-smads-UPP in a rat model of Diabetic Nephropathy

Background:

Astragali Radix and Lycopi Herba were widely used in clinical practice for treating the diabetic nephropathy (DN), but their therapeutic mechanisms were not clear.

Objective:

To observe the effects of the water-extraction of Astragali Radix and Lycopi Herba on the signaling pathway of TGF-Smads-UPP in streptozotocin (STZ)-induced DN.

Materials and Methods:

Sprague-Dawley (SD) rats were randomly divided into the normal control (NC) group and the model group. The NC group was fed with a standard diet and the other five diabetic groups received a high-fat diet. After 4 weeks, five diabetic groups were treated with STZ (30mg/kg i.p.). The NC group rats were treated with citrate buffer. Tail random blood glucose (RBG) was measured 72h later using a strip-operated blood glucose sensor and monitored every 2 weeks until drug intervention. Rats with RBG levels less than 16.7mmol/L were excluded from the diabetic groups. At the end of 4 weeks after STZ injection, 24h microalbuminuria was collected and detected. The microalbuminuria was measured by radioimmunoassay (RIA). The blood glucose was tested using a blood glucose meter. The kidney was dissected from each SD rat. Proteins and mRNA of TGF-β1, Smads and Smurf were tested by western-blot and real-time PCR analysis, and 26S proteasome activity was measured by an ELISA kit.

Results:

The water-extraction of Astragali Radix and Lycopi Herba significantly lowered fasting glucose and urine albumin in diabetic rats through inhibition of TGF-β1 mRNA and protein expression in the STZ-induced diabetic rats, and regulation of the Smad3, Smad7, Smurf1, Smurf2 mRNA and protein expression, as well as elevated 26S proteasome activity to play control effect in DN.

Conclusion:

0.9 g/ml water-extraction of Astragali Radix and Lycopi Herba group has significant therapeutic effects on the STZ-induced diabetic rats, and this regulation depends on TGF-Smads-UPP signaling pathway.

Changes in serum aldosterone are associated with changes in obesity-related factors in normotensive overweight and obese young adults

Recent data suggest excess circulating aldosterone promotes cardiometabolic decline. Weight loss may lower aldosterone levels, but little longitudinal data is available in normotensive adults. We aimed to determine whether, independent of changes in sodium excretion, reductions in serum aldosterone are associated with favorable changes in obesity-related factors in normotensive overweight/obese young adults. We studied 285 overweight/obese young adult participants (body mass index ≥ 25 and<40 kg m⁻², age 20-45 years) in a clinical trial examining the effects of a 1-year diet and physical activity intervention with or without sodium restriction on vascular health. Body weight, serum aldosterone, 24-h sodium and potassium excretion and obesity-related factors were measured at baseline, 6, 12 and 24 months. Weight loss was significant at 6 (7%), 12 (6%) and 24 months (4%; all P<0.0001). Decreases in aldosterone were associated with decreases in C-reactive protein, leptin, insulin, homeostasis assessment of insulin resistance, heart rate, tonic cardiac sympathovagal balance and increases in adiponectin (all P<0.05) in models adjusting for baseline age, sex, race, intervention arm, time since baseline, and sodium and potassium excretion. Weight loss and reductions in thigh intermuscular fat (intermuscular adipose tissue area; IMAT) were associated with decreases in aldosterone in the subgroup (n=98) with metabolic syndrome (MetS) at baseline (MetS × weight loss, P=0.04; MetS × change in IMAT, P=0.04). Favorable changes in obesity-related factors are associated with reductions in aldosterone in young adults with no risk factors besides excess weight, an important finding, given aldosterone's emergence as an important cardiometabolic risk factor.

Associations between arterial stiffness and platelet activation in normotensive overweight and obese young adults

Obese individuals have elevated platelet activation and arterial stiffness, but the strength and temporality of the relationship between these factors remain unclear. We aimed to determine the effect of increased arterial stiffness on circulating platelet activity in overweight/obese young adults. This analysis included 92 participants (mean age 40 years, 60 women) in the Slow Adverse Vascular Effects of excess weight (SAVE) trial, a clinical trial examining the effects of a lifestyle intervention with or without sodium restriction on vascular health in normotensive overweight/obese young adults. Carotid-femoral (cf), brachial-ankle (ba) and femoral-ankle (fa) pulse wave velocity (PWV) served as measures of arterial stiffness and were measured at baseline and 6, 12 and 24 months follow-up. Platelet activity was measured as plasma β-thromboglobulin (β-TG) at 24 months. Higher plasma β-TG was correlated with greater exposure to elevated cfPWV (p = 0.02) and baPWV (p = 0.04) during the preceding two years. After adjustment for serum leptin, greater exposure to elevated baPWV remained significant (p = 0.03) and exposure to elevated cfPWV marginally significant (p = 0.054) in predicting greater plasma β-TG. Greater arterial stiffness, particularly central arterial stiffness, predicts greater platelet activation in overweight/obese individuals. This relationship might partly explain the association between increased arterial stiffness and incident atherothrombotic events.

Reductions in arterial stiffness with weight loss in overweight and obese young adults: potential mechanisms

OBJECTIVE

Arterial stiffness decreases with weight loss in overweight/obese young adults. We aimed to determine the mechanisms by which this occurs.

METHODS

We evaluated carotid-femoral pulse wave velocity (cfPWV) and brachial-ankle pulse wave velocity (baPWV) in 344 young adults (23% male, BMI 25-40 kg/m(2)) at baseline, 6, and 12 months in a behavioral weight loss intervention. Linear mixed models were used to evaluate associations between weight loss and arterial stiffness and to examine whether improvements in obesity-related factors explained these associations.

RESULTS

At 6 months (7% mean weight loss), there was a significant median decrease of 47.5 cm/s in cfPWV (p < 0.0001) and a mean decrease of 11.7 cm/s in baPWV (p = 0.049). At 12 months (6% mean weight loss), only cfPWV remained reduced. In models adjusting for changes in mean arterial pressure and obesity-related factors, changes in BMI (p = 0.01) and common carotid artery diameter (p = 0.003) were positively associated with change in cfPWV. Reductions in heart rate (p < 0.0001) and C-reactive protein (p = 0.02) were associated with reduced baPWV and accounted for the association between weight loss and reduced baPWV.

CONCLUSIONS

Weight loss is associated with reduced cfPWV independently of changes in established hemodynamic and cardiometabolic risk factors, but its association with reduced baPWV is explained by concurrent reductions in heart rate and inflammation.

Serum aldosterone is associated with inflammation and aortic stiffness in normotensive overweight and obese young adults

Circulating aldosterone is increased in obesity and is associated with arterial stiffening in hypertensives and older adults. The aim of this article was to determine whether serum aldosterone is associated with pulse wave velocity (PWV), a measure of arterial stiffness, in normotensive overweight and obese adults aged 20-45 years (n = 344). Heart-femoral, femoral-ankle, and brachial-ankle PWV were measured. The sample was 77% female with mean body mass index 32.9 kg/m(2) (SD 3.9), median serum aldosterone 106.5 pg/mL (interquartile range 79.9, 155.5), and mean 24-hour urinary sodium excretion 185.9 mEq/day (SD 69.6). Higher serum aldosterone was not significantly correlated with any PWV measure in bivariate analysis. However, in multiple linear regression, adjusting for age, sex, race, height, heart rate, mean arterial pressure, and waist circumference, higher log aldosterone was associated with greater log heart-femoral PWV (β(se) = 0.042(0.021), P = .049). After adjusting for C-reactive protein, this association was no longer significant (β(se) = 0.035(0.021), P = .10). Circulating aldosterone may play an important role in vascular inflammation and aortic stiffening in normotensive overweight and obese adults.

High urinary sodium is associated with increased carotid intima-media thickness in normotensive overweight and obese adults

BACKGROUND

Increased dietary sodium has been reported to increase cardiovascular disease (CVD) risk, perhaps through blood pressure (BP)-independent vascular remodeling. Carotid intima-media thickness (IMT) is an accepted measure of structural vascular remodeling and a strong predictor of CVD. This study aimed to determine whether urinary sodium is positively associated with carotid IMT in normotensive overweight and obese adults.

METHODS

We evaluated baseline data from 258 participants in the Slow Adverse Vascular Effects (SAVE) clinical trial. Urinary sodium was measured from one 24-h urine collection from each individual. Carotid IMT was measured using high-resolution B-mode ultrasonography. Participants were categorized into quartiles of urinary sodium.

RESULTS

There was a significant positive trend with greater IMT associated with increasing urinary sodium quartile in univariate linear regression (P = 0.047). This trend was significant when adjusting for age, sex, race, and systolic BP (SBP) (P = 0.03) as well as in a fully adjusted model (P = 0.04). In pairwise comparisons, the highest urinary sodium quartile had a significantly greater mean IMT (0.62 mm) than the lowest urinary sodium quartile (0.59 mm) after adjustment for age, sex, race, and SBP (P = 0.04). This comparison lost significance after the addition of BMI.

CONCLUSIONS

In our community-based sample of normotensive overweight and obese adults, we observed a significant positive trend in carotid IMT with increasing quartile of urinary sodium. If the ongoing clinical trial confirms this relationship between sodium and carotid IMT, it would lend support to efforts to decrease sodium intake in overweight and obese individuals.

Sequence of progression of albuminuria and decreased GFR in persons with type 1 diabetes: a cohort study

BACKGROUND

The sensitivity of albuminuria in predicting loss of kidney function has been questioned. We determined the sequence of kidney disease stages (microalbuminuria, macroalbuminuria, low estimated glomerular filtration rate [eGFR], and end-stage renal disease [ESRD]) and characterized those without albuminuria before a low eGFR.

STUDY DESIGN

The Pittsburgh Epidemiology of Diabetes Complications Study is a prospective cohort investigation of childhood-onset type 1 diabetes.

SETTING & PARTICIPANTS

480 study participants with eGFR greater than 60 mL/min/1.73 m(2) (mean age, 27 years; diabetes duration, 19 years at study entry) were prospectively followed up for 16 years.

OUTCOMES & MEASUREMENTS

Low eGFR was defined as creatinine clearance less than 60 mL/min/1.73 m(2) from timed urine collections; microalbuminuria, as albumin excretion rate between 20 to 200 microg/min (30 to 300 mg/24 h); macroalbuminuria, as albumin excretion rate greater than 200 microg/min (>300 mg/24 h); and ESRD, as dialysis or renal transplantation.

RESULTS

The 33 of 480 individuals (7%) who developed ESRD had prior albuminuria. 71 of 480 (15%) individuals developed low eGFR. 66 of 71 (93%) had prior/concurrent albuminuria, and 5 of 71 (7%) did not. Incident low eGFR values in the 5 patients were: (1) 54, (2) 58, (3) 59, (4) 59.7, and (5) 59.8 mL/min/1.73 m(2). 3 of 5 (60%; patients 1, 4, and 5) subsequently developed albuminuria. Final eGFRs in the 5 patients were: (1) 94, (2) 86, (3) 60, (4) 65, and (5) 54 mL/min/1.73 m(2), respectively.

LIMITATIONS

GFR and insulin sensitivity were not measured, but estimated. Incident decreased eGFR in patients without preceding/concurrent albuminuria may be caused by misclassification or a temporary eGFR decrease.

CONCLUSIONS

Moderately decreased eGFR may occur rarely in patients with type 1 diabetes without preceding albuminuria.

Early nephropathy in type 1 diabetes: a new perspective on who will and who will not progress

Impaired renal function and end-stage renal disease (ESRD) affect up to a third of patients with type 1 diabetes. Thus, strategies for early detection and for preventative interventions are of critical importance. A model of diabetic nephropathy was developed in the 1980s that placed paramount importance on the finding of microalbuminuria as an early marker of a committed process of progressive kidney disease in diabetes. However, recent studies have provided evidence that microalbuminuria is a marker of dynamic, rather than fixed, kidney injury. Preliminary studies into early renal function decline, a process measured in early nephropathy using a simple assay for cystatin C to calculate the slope of glomerular filtration rate change over time, suggest that it is a more proximal marker than microalbuminuria of a person's trajectory toward impaired renal function and ESRD. Therefore, early renal function decline, rather than microalbuminuria, may be considered as the early marker of the committed process underlying progressive diabetic nephropathy.

Comparison of the effects of vitamins and/or mineral supplementation on glomerular and tubular dysfunction in type 2 diabetes

OBJECTIVE

The present study was designed to assess the effect of magnesium plus zinc, vitamins C plus E, and a combination of these micronutrients on nephropathy indexes in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

In a randomized, double-blind, placebo-controlled clinical trial, 69 type 2 diabetic patients were randomly divided into four groups, each group receiving one of the following daily supplement for 3 months: group M (n = 16), 200 mg Mg and 30 mg Zn; group V (n = 18), 200 mg vitamin C and 100 IU vitamin E; group MV (n = 17), minerals plus vitamins; and group P (n = 18), placebo. Urinary albumin excretion and N-acetyl-beta-d-glucosaminidase activity (NAG) in urine were determined at the beginning and at the end of the trial. Treatment effects were analyzed by general linear modeling.

RESULTS

Results indicate that after 3 months of supplementation, levels of urinary albumin excretion decreased in the V and MV groups (P = 0.034 and P = 0.005, respectively). Urinary NAG activity did not significantly change in any treatment groups. Levels of systolic, diastolic, and mean blood pressure significantly decreased in the MV group (P = 0.008, P = 0.017, and P = 0.009, respectively). Also, combination of vitamin and mineral supplementation had significant effects in decreasing fasting serum glucose (P = 0.035) and malondialdehyde concentrations (P = 0.004) and in increasing HDL cholesterol and apolipoprotein A1 levels (P = 0.019). There was no significant change in the levels of these parameters in the other three groups.

CONCLUSIONS

In conclusion, the results of the present study provide evidence for the effects of vitamins C and E and also combination of magnesium, zinc, and vitamins C and E supplementation on improvement of glomerular but not tubular renal function in type 2 diabetic patients.

The prevention of diabetic microvascular complications of diabetes: is there a role for lipid lowering?

The role of hyperglycemia in the development of microvascular complications of diabetes, such as nephropathy, retinopathy and neuropathy, has been well documented. Evidence is accumulating to support the concept that dyslipidemia can also contribute to the development of these complications. Lipid-lowering agents, such as statins, have been shown to prevent cardiovascular events in patients with diabetes. However, in addition to preventing macrovascular diseases, statins may also be able to retard the progression of microvascular complications of diabetes. Indeed, in addition to reducing lipid levels, these agents can improve endothelial function and reduce oxidative stress, which can improve microvascular function. These findings would provide further support for the use of lipid-lowering agents in patients with diabetes.

Angiotensin-I converting enzyme insertion/deletion polymorphism and its association with diabetic nephropathy: a meta-analysis of studies reported between 1994 and 2004 and comprising 14,727 subjects

AIMS/HYPOTHESIS

The ACE insertion/deletion polymorphism has been examined for association with diabetic nephropathy over the past decade with conflicting results. To clarify this situation, we conducted a comprehensive meta-analysis encompassing all relevant studies that were published between 1994 and 2004 and investigated this potential genetic association.

METHODS

A total of 14,727 subjects from 47 studies was included in this meta-analysis. Cases (n=8,663) were type 1 or 2 diabetic subjects with incipient (microalbuminuria) or advanced diabetic nephropathy (proteinuria, chronic renal failure, end-stage renal disease). Control subjects (n=6,064) were predominantly normoalbuminuric.

RESULTS

No obvious publication bias was detected. Using a minimal-case definition based on incipient diabetic nephropathy, subjects with the II genotype had a 22% lower risk of diabetic nephropathy than carriers of the D allele (pooled odds ratio [OR]=0.78, 95% CI=0.69-0.88). While there was a reduced risk of diabetic nephropathy associated with the II genotype among Caucasians with either type 1 or type 2 diabetes, the association was most marked among type 2 diabetic Asians (Chinese, Japanese, Koreans) (OR=0.65, 95% CI=0. 51-0.83). This OR is significantly different from the OR of 0.90 (95% CI= 0.78-1.04) that was obtained for type 2 diabetic Caucasians (p=0.019). Using a stricter case definition based on advanced diabetic nephropathy, a comparable risk reduction of 24-32% was observed among the three subgroups, although statistical significance was reached only among Asians.

CONCLUSIONS/INTERPRETATION

The results of our meta-analysis support a genetic association of the ACE Ins/Del polymorphism with diabetic nephropathy. These findings may have implications for the management of diabetic nephropathy using ACE inhibitors especially among type 2 diabetic Asians.

The role of lipids in the development of diabetic microvascular complications: implications for therapy

Dyslipidemia is a major factor responsible for coronary heart disease and its reduction decreases coronary risk in patients with diabetes mellitus. However, the association of dyslipidemia with microvascular complications and the effect of intervention with lipid-lowering therapy in diabetes have been less investigated. We present the systematic review of association and intervention studies pertaining to dyslipidemia and microvascular disease in diabetes and also review possible mechanisms. Dyslipidemia may cause or exacerbate diabetic retinopathy and nephropathy by alterations in the coagulation-fibrinolytic system, changes in membrane permeability, damage to endothelial cells and increased atherosclerosis. Hyperlipidemia is associated with faster decline in glomerular filtration rate and progression of albuminuria and nephropathy. Recent evidence also suggests a role of lipoprotein(a) in progression of retinopathy and nephropathy in patients with diabetes mellitus. Lipid-lowering therapy, using single agents or a combination of drugs may significantly benefit diabetic retinopathy and diabetic nephropathy. In particular, hydroxymethyl glutaryl coenzyme A reductase inhibitors may be effective in preventing or retarding the progression of microvascular complications because of their powerful lipid-lowering effects and other additional mechanisms. However, most of the data are based on short-term studies, and need to be ascertained in long-term studies. Until more specific guidelines are available, aggressive management of diabetic dyslipidemia, according to currently accepted guidelines, should be continued for the prevention of macrovascular disease which would also benefit microvascular complications.

Lipoproteins in the DCCT/EDIC cohort: associations with diabetic nephropathy

BACKGROUND

Lipoproteins may contribute to diabetic nephropathy. Nuclear magnetic resonance (NMR) can quantify subclasses and mean particle size of very low density lipoprotein (VLDL), low density lipoprotein (LDL), and high density lipoprotein (HDL), and LDL particle concentration. The relationship between detailed lipoprotein analyses and diabetic nephropathy is of interest.

METHODS

In a cross-sectional study, lipoproteins from 428 women and 540 men from the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) cohort were characterized by conventional lipid enzymology, NMR, apolipoprotein levels, and LDL oxidizibility. Linear regression was performed for each lipoprotein parameter versus log albumin excretion rate (AER), with and without covariates for age, diabetes duration, HbA1c, hypertension, body mass index, waist-hip ratio, and DCCT treatment group. Significance was taken at P < 0.05.

RESULTS

By multivariate analysis, conventional profile, total triglycerides, total- and LDL cholesterol, but not HDL cholesterol, were associated with AER. NMR-determined large, medium, and small VLDL were associated with AER in both genders (except large VLDL in women), and intermediate density lipoprotein (IDL) was associated with AER (men only). LDL particle concentration and ApoB were positively associated with AER (in men and in the total cohort), and there was a borderline inverse association between LDL diameter and AER in men. Small HDL was positively associated with AER and a borderline negative association was found for large HDL. No associations were found with ApoA1, Lp(a), or LDL oxidizibility.

CONCLUSION

Potentially atherogenic lipoprotein profiles are associated with renal dysfunction in type 1 diabetes and further details are gained from NMR analysis. Longitudinal studies are needed to determine if dyslipoproteinemia can predict patients at risk of nephropathy, or if lipoprotein-related interventions retard nephropathy.

Regression of microalbuminuria in type 1 diabetes

BACKGROUND

In the present study, we aimed to determine the frequency of a significant reduction in urinary albumin excretion and factors affecting such reduction in patients with type 1 diabetes and microalbuminuria.

METHODS

The study included 386 patients with persistent microalbuminuria, indicated by repeated measurements of urinary albumin excretion (estimated on the basis of albumin-to-creatinine ratios) in the range of 30 to 299 microg per minute during an initial two-year evaluation period. Subsequent measurements during the next six years were grouped into two-year periods, averaged, and analyzed for regression of microalbuminuria, which was defined as a 50 percent reduction in urinary albumin excretion from one two-year period to the next.

RESULTS

Regression of microalbuminuria was frequent, with a six-year cumulative incidence of 58 percent (95 percent confidence interval, 52 to 64 percent). The use of angiotensin-converting-enzyme inhibitors was not associated with the regression of microalbuminuria. However, microalbuminuria of short duration, salutary levels of glycosylated hemoglobin (less than 8 percent), low systolic blood pressure (less than 115 mm Hg), and low levels of both cholesterol and triglycerides (less than 198 mg per deciliter [5.12 mmol per liter] and 145 mg per deciliter [1.64 mmol per liter], respectively) were independently associated with the regression of microalbuminuria. Patients with salutary levels of all modifiable factors had a hazard ratio for regression of 3.0 (95 percent confidence interval, 1.5 to 6.0), as compared with patients with no salutary levels of any modifiable factor.

CONCLUSIONS

Frequent regression of microalbuminuria in patients with type 1 diabetes indicates that elevated urinary albumin excretion does not imply inexorably progressive nephropathy. Identification of the multiple determinants of the regression of microalbuminuria has implications for current theories about the mechanisms of early diabetic nephropathy.

Microalbuminúria em pacientes diabéticos tipo 1: prevalência e fatores associados

Para avaliar a freqüência da microalbuminúria e fatores clínicos e metabólicos associados, estudamos 72 pacientes com diabetes tipo 1 [DM1, 38F/34M, sendo 6 crianças, 17 adolescentes e 49 adultos, com 22,7±9,5 anos e 7 anos (0,1-37,5) de duração da doença]. A taxa de excreção de albumina (EUA) foi determinada em amostra noturna de urina de 10h. Microalbuminúria foi definida como EUA > ou = 20 e <200mig/min em pelo menos 2 de 3 amostras de urina, 25% mostraram-se microalbuminúricos (16 adultos e 2 adolescentes) e tinham maiores médias de idade (27,3±5,8 vs 20,9±10,1 anos, p<0,001), duração do DM [11,0 (0,1-17,0) vs 5,9 (1,0-37,5) anos, p<0,05], índice de massa corporal (22,7±2,6 vs 20,7±3,1, p<0,05), uréia (32,4±7,8 vs 28,3±5,9mg/dl, p<0,05), creatinina [0,7 (0,6-1,2) vs 0,6 (0,4-1,1) mg/dl, p<0,05] e maior freqüência de retinopatia (33% vs 9,4%, p<0,05) quando comparados aos normoalbuminúricos. Na regressão linear múltipla em stepwise, tendo a EUA como variável dependente, a única variável independente associada e preditora foi a idade (r²= 0,13, p<0,05). Concluímos que a idade foi um fator determinante no surgimento da microalbuminúria. Apesar de não termos observado microalbuminúria em crianças sugerimos que a triagem nesta faixa etária deve ser discutida no contexto específico de cada serviço de atendimento ao diabetes.

Does microalbuminuria predict diabetic nephropathy?

OBJECTIVE

To describe risk factors associated with microalbuminuria (MA) in subjects with diabetes, investigate the predictive value of MA as a marker of risk for diabetic nephropathy (DN), and define risk factors associated with the development and progression of MA.

RESEARCH DESIGN AND METHODS

We conducted a prospective longitudinal study of 23 diabetic subjects with persistent MA and 209 diabetic subjects without MA who attended diabetes clinics at the University of Michigan Medical Center in 1989 and 1990. Both groups were examined at baseline and after 7 years. At baseline, urinary albumin-to-creatinine ratios were studied in random, first morning, and 24-h urine samples. At follow-up, a 12-h overnight urine sample was collected and analyzed for albumin and creatinine. At baseline, MA was defined by at least two separate urine specimens with albumin-to-creatinine ratios between 30 and 299 microg albumin per milligram of creatinine.

RESULTS

MA regressed in 56% of subjects with baseline MA without systematic application of corrective measures and developed in 16% of subjects without baseline MA. The predictive value positive of MA as a marker of risk for DN was 43%, and the predictive value negative was 77%. In the combined cohort, the incidence and progression of MA were significantly associated with poor glycemic control and duration of diabetes between 10 and 14 years.

CONCLUSIONS

MA may not be as sensitive and specific a predictor of DN as previously suggested. Other markers of risk for DN are needed for optimal clinical management.

Renoprotection: one or many therapies?

BACKGROUND

Renal disease that progresses to end-stage renal disease (ESRD) imposes a great burden on the affected individual and on society, which mainly bears the cost of ESRD (currently more than $10 billion to treat about 333,000 patients annually in the U.S.). Thus, there is a great need to identify therapies that arrest the progression mechanisms common to all forms of renal disease. Progress is being made. Perhaps the most visible advance is the randomized controlled trials (RCT) demonstrating the renoprotective effects of angiotensin-converting enzyme (ACE) inhibitors. There are also numerous other promising renoprotective therapies. Unfortunately, testing each therapy in RCT is not feasible. Thus the nephrologist has two choices: restrict renoprotective therapy to those shown to be effective in RCT, or expand the use of renoprotective therapies to include those that, although unproven, are plausibly effective and prudent to use. The goal of this work is to provide the documentation needed for the nephrologist to choose between these strategies.

METHODS

This work first describes the mechanisms believed to be involved in the progression of renal disease. Based largely on this information, 18 separate interventions that slow the progression are described. Each intervention is assigned a level of recommendation (Level 1 is the highest and Level 3 the lowest) according to the strength of evidence supporting its renoprotective efficacy.

RESULTS

The number of interventions at each level of recommendation are: Level 1, N = 4; Level 2, N = 4; Level 3, N = 10. Our own experience with the multiple-risk-factor intervention is that most patients can achieve the majority of the Level 1 and 2 interventions, and many of the Level 3 interventions. We recommend the expanded renoprotection strategy.

CONCLUSION

This work advances the hypothesis that, until better information becomes available, a broad-based, multiple-risk-factor intervention intended to slow the progression of renal disease can be justified in those with progressive nephropathies. This work is intended primarily for clinical nephrologists and thus each recommended intervention is described in substantial practical detail.

Low-density lipoprotein apheresis retards the progression of hyperlipidemic overt diabetic nephropathy

BACKGROUND

Hyperlipidemia has recently received attention as being involved in the progression of diabetic nephropathy (DN). Low-density lipoprotein apheresis (LDL-A) can remove a large amount of plasma lipid directly from the patients in a short time.

METHODS

Fifteen type 2 diabetic patients with overt nephropathy received LDL-A in two different manners: short-term intensive therapy (SIT) for nine patients and long-term intermittent therapy (LIT) for six patients.

RESULTS

The changes in the monthly decline rates of reciprocal serum creatinine (1/Cr) were -0.035 +/- 0.020 in the three-month period before SIT, 0.047 +/- 0.041 during and until two weeks after SIT, and -0.035 +/- 0.015 after a period of two weeks from the therapy. The mean duration of LIT in six patients was 8.2 +/- 7.4 months, and the mean monthly decline rates of 1/Cr significantly decreased during the period of LIT as compared with the six-month period before the treatment.

CONCLUSION

LDL-A can retard the progression of overt DN, especially when it is performed repeatedly for a long period at two-week intervals.

Microalbuminuria in diabetes

Microalbuminuria is still the only early abnormality of the diabetic kidney that has an established prognostic value. Microalbuminuria evolves into clinical nephropathy and renal failure in a majority of cases of insulin-dependent diabetic patients, and is defined by the detection of urinary albumin excretion rates of 20-200 microg/min in timed urine collections. The occurrence of microalbuminuria at rates of 5-27 % of non-proteinuric patients and cost-benefit considerations justify the screening for microalbuminuria in diabetic outpatient clinics. Both near-normalisation of glycaemic control and treatment with ACE-inhibitors are indicated in patients with insulin-dependent diabetes to correct the progression of micro- to macroalbuminuria. Other therapeutic perspectives are being considered, but the current notion that the available therapies may not arrest the course of nephropathy at this stage suggests that earlier interventions may be required. Prevention of microalbuminuria and overt nephropathy may require a primary approach to the subset of patients with a genetic predisposition to this complication, and several studies (candidate gene or genomic scan with microsatellite probes) now address the chromosomal loci and the nature of the genes that may be involved.