Glomerular Filtration Rate In Diabetic Patients Research Articles

GLP-1 Receptor Agonists and Kidney Protection.

Type 2 diabetes mellitus (T2DM) is the leading cause of chronic kidney disease (CKD). Diabetic nephropathy (DN) is determined by specific pathological structural and functional alterations of the kidneys in patients with diabetes, and its clinical manifestations are albuminuria and decline of glomerular filtration rate (GFR). Apart from renin–angiotensin–aldosterone system (RAAS) inhibitors, no other drugs are currently available as therapy for diabetic kidney disease (DKD). Glucagon-like peptide-1 receptor (GLP-1R) agonists are a new class of anti-hyperglycemic drugs which have been demonstrated to prevent the onset of macroalbuminuria and reduce the decline of GFR in diabetic patients. These drugs may exert their beneficial actions on the kidneys through blood glucose- and blood pressure (BP)-lowering effects, reduction of insulin levels and weight loss. Clinical benefits of GLP-1R agonists were acknowledged due to data from large randomized phase III clinical trials conducted to assess their cardiovascular(CV) safety. These drugs improved renal biomarkers in placebo-controlled clinical studies, with effects supposed to be independent of the actions on glycemic control. In this review, we will focus on the actions of GLP-1R agonists on glucose metabolism and kidney physiology, and evaluate direct and indirect mechanisms through which these drugs may confer renal protection.

The rs12917707 polymorphism at the UMOD locus and glomerular filtration rate in individuals with type 2 diabetes: evidence of heterogeneity across two different European populations.

UMOD variability has been associated at a genome-wide level of statistical significance with glomerular filtration rate (GFR) in Swedish individuals with type 2 diabetes (T2D; n = 4888). Whether this finding is extensible also to diabetic patients from other populations deserves further study. Our aim was to investigate the relationship between UMOD variability and GFR in patients with T2D from Italy. Genotyping of the single nucleotide polymorphism (SNP) rs12917707 at the UMOD locus has been carried out in 3087 individuals from four independent Italian cohorts of patients with T2D by TaqMan allele discrimination. In none of the four study cohorts was rs12917707 significantly associated with GFR (P > 0.05 for all). Similar results were obtained when the four samples were pooled and analyzed together (β = 0.83, P = 0.19). Such effect was strikingly smaller than that previously reported in Swedish patients (P for heterogeneity = 1.21 × 10-7). The previously reported strong association between rs12917707 and GFR in diabetic patients from Sweden is not observed in Italian diabetic patients, thus clearly pointing to a heterogeneous effect across the two different samples. This suggests that UMOD is a strong genetic determinant of kidney function in patients with T2D in some, but not all, populations.

Comment on Tsuda et al. Poor Glycemic Control Is a Major Factor in the Overestimation of Glomerular Filtration Rate in Diabetic Patients. Diabetes Care 2014;37:596–603

Accurate assessment of kidney function is of major clinical importance for the management of patients with diabetes. We read with interest the article by Tsuda et al. (1). The authors proposed a new equation to estimate glomerular filtration rate (GFR), including glycemic control as a new variable. They concluded that poor glycemic control is a major factor in the overestimation of GFR in diabetic patients. There are several important limitations in this study. First, the sample ( n = 80, all Japanese subjects) must be considered as too limited to propose a new equation. For …

The IRS1 G972R polymorphism and glomerular filtration rate in patients with type 2 diabetes of European ancestry

In Mexican Americans, the IRS1 G972R polymorphism (rs1801278) has been associated to such a marked reduction in glomerular filtration rate (GFR) (i.e. β = -8.3 mL/min/1.73 m(2)) to be considered a major determinant of kidney function. This was a cross-sectional study to investigate whether a similarly strong effect can also be observed among individuals of European ancestry. We investigated a total of 3973 White patients with type 2 diabetes. Standardized serum creatinine was measured by the modified kinetic Jaffè reaction and estimated GFR (eGFR) calculated by the modification diet renal disease (MDRD) formula; rs1801278 was genotyped by TaqMan assay. No significant association was observed, with R972 carriers showing only a modestly, not significant, lower eGFR level as compared with other subjects (β = -1.82 mL/min/1.73 m(2), P = 0.086). Our data indicate that IRS1 G972R is not a strong determinant of GFR in diabetic patients of European ancestry as in Mexican Americans. Since we had 100% power to detect the previously reported association, the risk our finding is a false negative one is minimal.

Effect of glycaemic control on glomerular filtration rate in diabetes mellitus patients.

Glomerular filtration rate (GFR) is a widely accepted parameter in assessing overall renal function. This study sought to assess the effect of glucose lowering on GFR in diabetic patients admitted for short term therapy at Mulago hospital. This was a descriptive study where consenting patients were consecutively recruited. Glomerular filtration rate was measured using creatinine clearance in 40 type I and II diabetes mellitus patients admitted on the basis of a glucometer reading of RBS >or= 300 mg/dl both at admission and discharge. Data was analyzed using a paired sample t-test and p-value set at 0.05 (95% CI). A total of 40 patients were assessed. Their mean age was 49.8 years. 82.5% of them had type II DM while only 17.5% had type I DM. The average duration of disease was 7 years. GFR was found to decrease from 157.4 ml/min on admission to 86.4 ml/min at discharge (p=0.001). Random blood sugar levels decreased from 332.2mg/dl on admission to 119.8 mg/dl at discharge (p=0.000). Results imply that glycaemic control lowers the GFR in diabetic patients admitted for short term treatment. A reduction in GFR reflects reduction of hyperfiltration, a process that starts diabetic nephropathy. Good glycaemic control will go along way to delay onset of diabetic nephropathy.

Cystatin C improves the diagnosis and stratification of chronic kidney disease, and the estimation of glomerular filtration rate in diabetes

Aims Estimation of glomerular filtration rate (GFR) is recommended to diagnose and stratify chronic kidney disease (CKD). Can cystatin-C (cysC) assay improve the results in diabetic patients? Methods In 124 diabetic patients with a wide range of GFR, as determined by 51Cr-EDTA clearance (i-GFR), we estimated ‘e-GFR’ by: the recommended Cockcroft–Gault (CG) formula and Modification of Diet in Renal Disease (MDRD) study equation; the new Mayo Clinic quadratic (MCQ) equation; the recently proposed composite estimation including both serum creatinine and cysC; and a simplified approach dividing the MDRD by cysC if less than 1.10 mg/L. Results The highest diagnostic accuracy (receiver operating characteristic [ROC] curves) and the highest proportions of well-stratified patients were obtained by cysC and the MDRD which, however, underestimated i-GFR for patients without CKD (−17%, P < 0.001). The CG overestimated GFR in KDOQI stages 1 and 2, ignored stage 5 and was the least accurate. The MCQ equation overrepresented stage 2, overestimating GFR at this stage (+23%, P < 0.005). The composite estimation (54.7 ± 27.0 mL per minute 1.73 m 2) correlated best with i-GFR (56.1 ± 35.3; r = 0.90, P < 0.001), and did not significantly differ from it across the entire population and within each Kidney Disease Outcome Quality Initiative (KDOQI) stage but was also biased (Bland–Altman procedure). Simply dividing the MDRD by cysC if less than 1.10 mg/L produced a comparable performance and eliminated the bias. Conclusion The recommended creatinine-based estimations of GFR need to be improved. CysC assay helps in the diagnosis and stratification of CKD and leads to better estimates of GFR in diabetic patients without any substantial increase in complexity.

Effects of smoking on renal function in patients with type 1 and type 2 diabetes mellitus

Smoking increases the risk of end-stage renal failure in patients with primary renal disease. Whether and to what extent smoking affects the kidneys in diabetic patients with normal renal function and variable degrees of proteinuria has not been fully studied. We followed 185 patients with type 1 or 2 diabetes mellitus and with or without signs of overt renal disease for at least 3 years, median 5.1 (3-6.8) years. Each patient had a baseline visit and at least four follow-up visits (average 4.8+/-0.3). Cases were patients who were smoking (n = 44) at the time the survey was started. Controls were patients who had never smoked (n = 141). Glomerular filtration rate (GFR) was estimated using the MDRD formula. Multiple logistic regression was used to correct for confounding factors. At baseline, smokers were younger (47+/-14 vs 54+/-16 years, P < 0.01), and had a lower GFR (95+/-26 ml/min) than non-smokers (107+/-33 ml/min, P < 0.05). Mean GFR remained constant during follow-up in non-smokers (106+/-31 ml/min), but decreased significantly in smokers (83+/-22 ml/min, P < 0.0001), and this relationship persisted when adjusted for retinopathy, glycaemic control, age, body habitus, ACE-inhibitor treatment, blood pressure control or severity of proteinuria. The effect of smoking on GFR decline was stronger in patients with type 1 diabetes or male gender. Cigarette smoking causes a decrease in GFR in diabetic patients with normal or near-normal renal function, independent of confounding factors including severity of proteinuria. The latter finding suggests a mechanism independent of glomerular damage.

The impact of glycaemic control on autoregulation of glomerular filtration rate in patients with non-insulin dependent diabetes

The ability of the kidney to maintain constancy of glomerular filtration rate (GFR) over a wide range of renal perfusion pressures is termed autoregulation. Defective autoregulation of GFR has been demonstrated in patients with diabetic and non-diabetic nephropathy and in streptozotocin diabetic rats during hyperglycaemia. Information on the potential impact of acute changes in glycaemic control on autoregulation of GFR in diabetic patients is lacking. Therefore the aim of our study was to evaluate the effect of acute lowering of blood pressure (BP) on GFR during normoglycaemia and hyperglycaemia. We investigated 14 (12m/2f) normoalbuminuric patients with non-insulin dependent diabetes (NIDDM). The patients were examined in random order on two separate days with blood glucose (BG)<10 mmol/L or with BG>15 mmol/L. GFR (single shot [51Cr] EDTA plasma clearance technique) was measured twice each day; first without clonidine (baseline) followed by intravenous injection of clonidine 100-150 microg. We measured BG (One Touch 2), and BP (Takeda TM2420) several times during each GFR measurement. Clonidine reduced mean arterial blood pressure with 20 (1.4) vs. 16 (1.2) mmHg (mean (SE)) with BG<10mmol/L and with BG>15 mmol/L, respectively (p=0.053). GFR diminished in average from 92 (3.1) to 86 (3.7) ml/min/1.73m2 with BG<10 mmol/L (p<0.05), and from 102 (4.1) to 98 (4.2) ml/min/1.73 m2 with BG> 15 mmol/L, NS. Mean difference between changes in GFR (95% confidence interval) between the examination with BG<10 mmol/L and with BG>15 mmol/L were 2.3 (-1.3 to 5.9) ml/min/1.73 m2 (NS). The mean BG during normoglycaemia was 6.9 (0.3) vs.16.9 (0.4) during hyperglycaemia. Our study suggests that acute changes in glycaemic control have no detectable effect on autoregulation of GFR in NIDDM patients. Hyperglycaemia enhances GFR.

Glomerular filtration rate determination in diabetic patients using iohexol clearance — comparison of single and multiple plasma sampling methods

Use of iohexol clearance has been described as the gold standard for the measurement of glomerular filtration rate (GFR). It is suggested that multiple plasma sampling following iohexol injection is required to accurately determine GFR by area under plasma clearance curve. The aim of this study was to determine whether single plasma sampling 4 h after injection of iohexol could accurately determine GFR in diabetic patients with mild to moderate renal failure, compared to multiple plasma sampling. A total of 120 GFR determinations in 36 patients with non-insulin dependent diabetic renal disease were done over 1 year. No acute deterioration was seen in renal function following injection of contrast in any patient. Strong correlation in GFR measurement was observed between the multiple plasma sampling method and the single plasma sampling method ( r 2=0.975). Single plasma sampling 4 h after bolus injection of iohexol is a safe and accurate method of determining GFR and change in GFR in diabetic subjects with mild to moderate renal impairment.

Effects of acute protein loads of different sources on renal function of patients with diabetic nephropathy.

To evaluate effects of acute loading of different proteins on renal function, glomerular filtration rate (GFR), albumin excretion rate (AER), and concentrations of plasma amino acids, 11 normal volunteers and 20 diabetic patients were studied before and after eating 1.0 g/kg body weight of either tuna fish meal or bean curd on separate days. In normal subjects, the mean baseline GFR was 115.8 +/- 9.5 ml/min/1.73 m2, and the mean GFRs after ingestion of tuna fish meal were 134.1 +/- 15.5 (1 hr), 146.2 +/- 18.8 (2 hr), and 157.8 +/- 21.2 (3 hr), respectively. GFR did not significantly increase in normal subjects after ingestion of bean curd. GFR in diabetic patients with normoalbuminuria after ingestion of each protein was similar to the response in normal subjects. In diabetic patients with microalbuminuria, GFR did not significantly increase after ingestion of each protein. In diabetes with macroalbuminuria, GFR decreased after ingestion of tuna fish meal and did not significantly change after intake of bean curd. In both normal subjects and diabetic patients, urinary AER did not increase after each kind of protein loading. Plasma concentrations of alanine, glycine, and arginine, known to induce glomerular hyperfiltration, increased to a greater degree after ingestion of tuna fish meal than after administration of bean curd. These findings suggest that responses of GFR to acute protein loading may differ according to the amino acid composition of the protein ingested and to the stage of diabetic nephropathy.