Comparative Assessment of plasma Cystatin C, β2 Microgloulin and Creatinine as Markers of Renal Function in Sudanese patients with Type2 Diabetes

Abstract

Background: Cystatin C and B2-macroglobulin, are mainly used as biomarkers of kidney function. Because of their small size, Cystatin C andB2-microglobulin are freely filtered by the glomeruli, and dose not return to the blood stream or secreted by renal tubules. They have been suggested to be closer to the “ideal” endogenous marker, and emerging as a biomarker superior to serum creatinine for estimating the glomerular filtration rate and predicting the risk of death and cardiovascular events. Diabetic nephropathy cause gradual renal impairment, that may end with end stage renal failure. In glomerular kidney disease, the glomeruli can't filter cystatin C and B2- microglobulin out of the blood, so levels increase in blood and decrease in urine. Objectives: To assess the plasma levels of cystatin C, B2- microglobulin, creatinine, creatinine clearance, blood HbA1C% and body mass index among Sudanese patients with type 2 diabetes in comparison with healthy controls. Materials and methods: This is a case-control study conducted in Jabir Abulizz and Almolazmeen diabetic centers in Khartoum state, Sudan, during the period from November 2010 to March 2014. A total of 300 Sudanese patients with type2 diabetes mellitus (49%males and 51% females)as a test group and 150 healthy subjects(48%males and 52%female) as a control group were enrolled in this study. The test group and the control group were matched in term of gender and age. The plasma levels of cystatin c, B2-microglobulin, creatinine and blood HbA1c% were measured using Nephelometry technique. creatinine clearance was calculated and the body mass index was determined for each participant. SPSS was used for analysis of data. Student's “t” test was used for comparison between the test group and the control group and Pearson’s correlation was used to assess correlations between variables. Results: In the current study the majority of diabetic patients were found to be obese (71%), with long standing diabetes (65%) and had uncontrolled diabetes (69%). The means of the plasma levels of cystatin C, B2-microglobulin, creatinine , blood HbA1c% and body mass index were significantly raised in the diabetic group when compared to the control group (p<0.05).The study showed a significant positive correlation between the plasma levels of cystatin C and creatinine , and a significant moderate positive correlation between the plasma levels of cystatin c and HbA1c % of the diabetic group. In the present study there was significant moderate positive correlations between HbA1c% and plasma levels of both; cystatin C and B2-microglobulin, whereas creatinine clearance had significant inverse moderate correlations with both; cystatin C and B2-microglobulin. Conclusion: From the results of this study it is concluded that: plasmacystatin c, B2-microglobulin,creatinine,HbA1c% and body mass index are raised in Sudanese with type 2diabetes. Plasma cystatin C and B2-microglobulin have significant inverse correlations with the glomerular filtration rate. Both cystatin C and B2-microglobulin plasma levels have significant positive moderate correlations with HbA1c%.Tthe plasma levels of cystatin C and B2-microglobulin could be used as markers of renal function and glycemic control in patients with type 2 diabetes.