Serum Cystatin C Levels are Positively Associated with Cardiovascular Autonomic Neuropathy in Patients with Type 2 Diabetes

Novel biomarkers for prognosticating diabetic kidney disease progression

The global burden of diabetic kidney disease (DKD) is escalating, and it remains as a predominant cause of the end-stage renal disease (ESRD). DKD is associated with increased cardiovascular disease and morbidity in all types of diabetes. Prediction of progression with albuminuria and eGFR is challenging in DKD, especially in non-proteinuric DKD patients. The pathogenesis of DKD is multifactorial characterized by injury to all components of the nephron, whereas albuminuria is an indicator of only glomerular injury. The limits in the diagnostic and prognostic value of urine albumin demonstrate the need for alternative and clinically significant early biomarkers, allowing more targeted and effective diabetic treatment, to reduce the burden of DKD and ESRD. Identification of biomarkers, based on multifactorial pathogenesis of DKD can be the crucial paradigm in the treatment algorithm of DKD patients. This review focuses on the potential biomarkers linked to DKD pathogenesis, particularly with the hope of broadening the diagnostic window to identify patients with different stages of DKD progression.

Association of circulating cystatin C levels with type 2 diabetes mellitus: a systematic review and meta-analysis

INTRODUCTION

This study aimed to systemically summarize the present literature about circulating cystatin C (Cys C) levels in type 2 diabetes mellitus (T2DM) and provide a more precise evaluation of Cys C levels in T2DM.

MATERIAL AND METHODS

Relevant studies about Cys C concentrations in T2DM were searched in PubMed, EMBASE and the Cochrane Library database (up to Oct 31 2018). We computed the pooled standard mean difference (SMD) with its 95% confidence interval (CI) of Cys C levels through a random-effect model. The Q test and the I² statistic were used to assess and quantify between-study heterogeneity; publication bias was evaluated through a funnel plot and Egger's linear regression test.

RESULTS

After the literature search and screening process, 14 studies with 723 T2DM patients and 473 healthy controls were finally included in the meta-analysis. The results showed that T2DM patients had significantly higher Cys C levels compared to healthy controls (SMD = 1.39, 95% CI: 0.92-1.86, p < 0.001). Publication bias was not detected based on the symmetrical shape of the funnel plot and the results of Egger's test (p = 0.452). Subgroup analyses suggested that variables of human race, age, gender, study sample size and disease duration have a relationship with Cys C level in T2DM patients.

CONCLUSIONS

Overall, our study suggests that patients with T2DM have an elevated circulating Cys C level compared to healthy controls, and it is associated with race, age, gender, study sample size and disease duration. Further investigations are still needed to explore the causal relationship of aberrant Cys C concentrations in T2DM.

Correlation between the levels of serum cystatin C and substance P in peripheral blood in diabetes mellitus patients complicated with hypertension

Correlation between the serum cystatin C and substance P in peripheral blood of diabetes mellitus patients complicated with hypertension was investigated. Diabetes mellitus patients with or without hypertension were selected in No. 215 Hospital of Shaanxi Nuclear Industry from December 2015 to February 2017. There were 60 patients with only hypertension (hypertension control group), 60 patients with only diabetes mellitus (diabetes mellitus control group) and 60 patients with diabetes mellitus combined with hypertension (observation group). Levels of serum cystatin C and substance P in peripheral blood were measured via immunoturbidimetry and enzyme-linked immunosorbent assay, respectively, and the correlation with hypertension was analyzed. The average level of serum cystatin C in the observation group was higher than that of the two control groups (P<0.05). The level of substance P in peripheral blood of the observation group was lower than that of the diabetic control group (P<0.05). The levels of serum cystatin C in patients with grade III hypertension in observation group were higher than those in grades II and I, and the levels of substance P in peripheral blood of patients with grade III hypertension in observation group were lower than those in grades II and I. Systolic pressure of patients in observation group was significantly positively correlated with level of serum cystatin C, but significantly negatively correlated with level of substance P in peripheral blood (P<0.05). Compared with the diabetes mellitus patients, level of serum cystatin C was higher, and level of substance P peripheral blood was lower in diabetes mellitus patients complicated with hypertension. In diabetes mellitus patients, blood pressure was positively correlated with serum cystatin C level, and negatively correlated with substance P level in peripheral blood.