Determinants of decline in glomerular filtration rate in nonproteinuric subjects with or without diabetes and hypertension

Relationship between BNP level and renal function in diabetic nephropathy with microalbuminuria

AIMS

We examined the relationship between the brain natriuretic peptide (BNP) level and renal function in diabetic nephropathy with microalbuminuria.

METHODS

The subjects were 97 Japanese type 2 diabetes mellitus outpatients with microalbuminuria. Associations between the annual rate of decline in estimated glomerular filtration rate (eGFR) and various metabolic parameters at baseline (BMI, systolic blood pressure, HbA1c, LDL cholesterol, urine albumin-creatinine ratio, BNP and eGFR) were examined.

RESULTS

Among the baseline factors, eGFR and BNP had significant associations with the annual rate of decline in eGFR in Pearson correlation analysis (r=0.295, p=0.003; r=0.223, p=0.028, respectively). Multiple linear regression analysis also showed the significance of baseline eGFR and BNP as independent predictors of renal function (β=0.340, p=0.001; β=0.278, p=0.005, respectively). In multivariate logistic regression analysis, eGFR and BNP were independently associated with the risk of a decline in GFR (p=0.003, p=0.011, respectively). ROC curve analysis showed a cutoff value of BNP is 17.0 pg/mL for predicting a decline in GFR.

CONCLUSIONS

The BNP level at baseline is an independent predictor of the annual rate of decline in eGFR. Therefore, monitoring of BNP can play an important role in management of diabetic nephropathy.

The independent relationship between creatinine clearance, microalbuminuria and circadian blood pressure levels in newly diagnosed essential hypertensive and type 2 diabetic patients

BACKGROUND AND OBJECTIVES

Increased evidence suggests that apart from patients with increased albumin excretion and decreased glomerular filtration rate (GFR); there are also patients with type 2 diabetes with decreased GFR but without albuminuria. The exact pathophysiologic mechanisms regarding these clinical conditions are not known. We suggest that different blood pressure (BP) levels may be one the factors for these different clinical conditions. However, before labeling BP as a causative factor; one must show whether BP levels are different in these patients. Thus the current study was performed to analyze the relationship between creatinine clearance, microalbuminuria and circadian blood pressure levels in newly diagnosed essential hypertensive and type 2 diabetic patients.

METHODS

Medical history, physical examination, laboratory analysis and ambulatory blood pressure measurements (ABPMs) were analyzed. 24-h urine specimens were collected to measure creatinine clearance and albumin excretion

RESULTS

In total 216 patients were included which were divided into 4 groups: group 1 composed of 90 patients with normal GFR and without microalbuminuria (MA), group 2 composed of 50 patients with normal GFR and with MA, group 3 composed of 36 patients with decreased GFR and without MA and group 4 composed of 40 patients with both decreased GFR and MA. The ratio of dippers vs. non dippers was not different between group 1, group 2 and group 3 patients. However ratio of dippers was higher in group 1 when compared to group 4 (P: 0.003) and group 4 patients have an odds of 7.678 (CI: 1.657-35.576, P: 0.009) for non-dapping status when compared to patients in group 1.

CONCLUSION

In conclusion, ABPM measurements were highest in patients with both decreased GFR and MA, whereas they are lowest in patients with normal GFR and normal UAE.

Comparison of renal resistive index among patients with Type 2 diabetes with different levels of creatinine clearance and urinary albumin excretion

AIM

To evaluate the prevalence of increased renal resistive index and related factors among patients with Type 2 diabetes with different levels of creatinine clearance and urinary albumin excretion.

METHODS

Laboratory analyses, including calculation of 24-h urinary albumin excretion and 24-h creatinine clearance, and renal doppler ultrasonography to measure renal resistive index, were carried out for patients newly diagnosed with Type 2 diabetes mellitus.

RESULTS

Participants were classified into four groups according to 24-h creatinine clearance and 24-h urinary albumin excretion levels. Group 1 was composed of 73 patients (54.1%) with normal 24-h creatinine clearance and 24-h urinary albumin excretion. Group 2 was composed of 34 (25.2%) patients with normal 24-h creatinine clearance and increased 24-h urinary albumin excretion. Group 3 was composed of 14 (10.4%) patients with decreased 24-h creatinine clearance and normal 24-h urinary albumin excretion. Group 4 was composed of 14 (10.4%) patients with both decreased 24-h creatinine clearance and increased 24-h urinary albumin excretion . In total, 41 patients (30.4%) had increased renal resistive index levels. Comparison of the four groups with respect to increased renal resistive index revealed: among group 1 patients, 10 (13.7%) had increased renal resistive index levels; among group 2 patients, 14 (41.2%) had increased renal resistive index levels; among group 3 patients, eight (57.1%) had increased renal resistive index levels; among group 4 patients, nine (64.3%) had increased renal resistive index levels (P<0.0001 for trend). In multivariate regression, 24-h creatinine clearance (P<0.0001), but not 24-h urinary albumin excretion, was related to increased renal resistive index levels.

CONCLUSION

Renal resistive index levels were highest in patients with Type 2 diabetes with both decreased 24-h creatinine clearance and increased 24-h urinary albumin excretion, whereas they were lowest in patients with normal creatinine clearance and normal urinary albumin excretion.

Predictors of estimated GFR decline in patients with type 2 diabetes and preserved kidney function

BACKGROUND AND OBJECTIVES

This study examined predictors of the annual decline in estimated GFR (eGFR) in patients with type 2 diabetes and preserved kidney function.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a prospective, observational cohort study, 1682 individuals with type 2 diabetes and baseline eGFR ≥60 ml/min per 1.73 m(2) (as estimated by the Chronic Kidney Disease Epidemiology Collaboration equation) were followed for 10 years. Linear regression was used to estimate participants' changes in eGFR over time.

RESULTS

During follow-up, 263 (15.6%) individuals had a rapid eGFR decline defined as >4.0% per year. Average eGFR decline was -5.8 ± 3 and -0.6 ± 2 ml/min per 1.73 m(2) per year in rapid decliners and nondecliners, respectively. Compared with normotensive, normoalbuminuric patients (-0.2 ± 0.2 ml/min per 1.73 m(2) per year), those with hypertension (-1.0 ± 0.1 ml/min per 1.73 m(2) per year), hemoglobin A(1c)≥7% (-1.0 ± 0.1 ml/min per 1.73 m(2) per year), longer diabetes duration (-1.0 ± 0.1 ml/min per 1.73 m(2) per year), obesity (-1.2 ± 0.1 ml/min per 1.73 m(2) per year), insulin treatment (-1.5 ± 0.1 ml/min per 1.73 m(2) per year), microalbuminuria (-1.3 ± 0.2 ml/min per 1.73 m(2) per year), or macroalbuminuria (-2.7 ± 0.4 ml/min per 1.73 m(2) per year) had significantly faster age-adjusted annual eGFR declines. Multivariable linear regression analyses revealed that albuminuria (P<0.001) was the strongest predictor of annual eGFR decline. Other independent predictors of annual eGFR decline were older age, hypertension, insulin treatment, and lower baseline eGFR.

CONCLUSIONS

Annual eGFR decline is predicted by multiple modifiable risk factors in patients with type 2 diabetes and preserved kidney function.

Arterial stiffness is associated with incident albuminuria and decreased glomerular filtration rate in type 2 diabetic patients

OBJECTIVE

To investigate the association between aortic stiffness and incident albuminuria and the decline in estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

We investigated 461 Japanese type 2 diabetic patients, comprising 199 women and 262 men, with a mean age of 59 ± 11 years. Patients were divided into two groups according to the median value of carotid-femoral pulse wave velocity (cf-PWV), which was used to evaluate aortic stiffness. The end point was defined as the transition from normo- to microalbuminuria or micro- to macroalbuminuria. The Cox proportional hazard model was used to calculate the hazard ratio (HR) and 95% CI. The correlation between cf-PWV and rate of change in eGFR was also determined by linear regression analysis.

RESULTS

The baseline mean (± SD) cf-PWV was 9.6 ± 2.4 m/s. During a median follow-up period of 5.9 years (range 0.3-8.6), progression of albuminuria was observed in 85 patients. The 5-year cumulative incidence of the end point in patients with cf-PWV below and above the median was 8.5 and 19.4%, respectively (P = 0.002, log-rank test). cf-PWV was significantly associated with incident albuminuria (HR 1.23, 95% CI 1.13-1.33, P < 0.001) by multivariate Cox regression analysis. A significant association between cf-PWV and annual change in eGFR was also suggested by multiple linear regression analysis (standardized estimate -0.095, P = 0.031).

CONCLUSIONS

Aortic stiffness is associated with incident albuminuria and the rate of decline in glomerular filtration rate in type 2 diabetic patients.

Time-dependent impact of diabetes on the mortality of patients on renal replacement therapy: a population-based study in Germany (2002-2009)

AIMS

To estimate the impact of diabetes on the mortality of patients with incident renal replacement therapy (RRT).

METHODS

We assessed the mortality of 544 incident RRT patients aged ≥ 30 years between 2002 and 2009 (57.9% men, mean age 70.3 years, 49.6% patients with diabetes) by analyzing the data of all dialysis centers covering a German region. We compared the estimated time-dependent hazard ratios of patients with and without diabetes by using the Cox proportional-hazards regression model.

RESULTS

Overall, 319 patients had died (158 diabetic), approximately 50% after 3 years. Up to about 3 years, the mortality rate was lower in diabetic than in nondiabetic patients. Thereafter, the survival curves crossed (interaction diabetes × time, p = 0.002; adjusted hazard ratios for diabetes: baseline, 0.66; year 1, 0.84; year 2, 1.05; year 3, 1.33; year 4, 1.68). The results were similar in men and women; however, the interaction of diabetes and time was significant only in men (p = 0.004). Further significant risk factors of mortality were age, sex, initial central venous catheter, cardiovascular disease, and malignancy.

CONCLUSIONS

In this population-based study, the influence of diabetes was time-dependent, with a lower mortality in diabetic versus non-diabetic patients in the first three years but a higher mortality in these patients after 3 years. Results were similar in men and women.

Association between urinary type IV collagen level and deterioration of renal function in type 2 diabetic patients without overt proteinuria

OBJECTIVE

Cross-sectional studies have reported increased levels of urinary type IV collagen in diabetic patients with progression of diabetic nephropathy. The aim of this study was to determine the role of urinary type IV collagen in predicting development and progression of early diabetic nephropathy and deterioration of renal function in a longitudinal study.

RESEARCH DESIGN AND METHODS

Japanese patients with type 2 diabetes (n = 254, 185 with normoalbuminuria and 69 with microalbuminuria) were enrolled in an observational follow-up study. The associations of urinary type IV collagen with progression of nephropathy and annual decline in estimated glomerular filtration rate (eGFR) were evaluated.

RESULTS

At baseline, urinary type IV collagen levels were higher in patients with microalbuminuria than in those with normoalbuminuria and correlated with urinary beta(2)-microglobulin (beta = 0.57, P < 0.001), diastolic blood pressure (beta = 0.15, P < 0.01), eGFR (beta = 0.15, P < 0.01), and urinary albumin excretion rate (beta = 0.13, P = 0.01) as determined by multivariate regression analysis. In the follow-up study (median duration 8 years), urinary type IV collagen level at baseline was not associated with progression to a higher stage of diabetic nephropathy. However, the level of urinary type IV collagen inversely correlated with the annual decline in eGFR (gamma = -0.34, P < 0.001). Multivariate regression analysis identified urinary type IV collagen, eGFR at baseline, and hypertension as factors associated with the annual decline in eGFR.

CONCLUSIONS

Our results indicate that high urinary excretion of type IV collagen is associated with deterioration of renal function in type 2 diabetic patients without overt proteinuria.