Diabetes Metab J > Volume 40(2); 2016 > Article
Kim: Letter: The Association of Serum Cystatin C with Glycosylated Hemoglobin in Korean Adults (Diabetes Metab J 2016;40:62-9)
Cystatin C is a more sensitive indicator of mild renal impairment and better estimates the glomerular filtration rate than serum creatinine [1]. Recently, cystatin C has been suggested to provide information beyond renal function. Several studies suggested that cystatin C is associated with obesity, atherosclerosis, insulin resistance, and hypertension [2,3]. Furthermore, in Western populations, elevated levels of serum cystatin C are associated with prediabetes or diabetes [4,5,6].
In this article entitled "The association of serum cystatin C with glycosylated hemoglobin in Korean adults," Sim et al. [7] evaluated the association between cystatin C and prevalence of diabetic conditions defined by glycosylated hemoglobin (HbA1c) levels in Korean adults. They described that higher levels of serum cystatin C are associated with an increased prevalence of diabetic conditions in Korean adults. Interestingly, the positive association between cystatin C and diabetic conditions was not significant in the multivariable models, and this result was consistent with a previous study [6]. Although the ethnic differences in this association are not fully understood, the association between cystatin C and diabetic conditions may be weaker in Asian populations compared to white populations. However, there are several issues that need to be discussed.
First, Sabanayagam et al. [6] examined the association between serum cystatin C and prediabetes in non-obese United States adults. They examined 2,033 participants from the National Health and Nutrition Examination Survey 1999 to 2002, aged ≥20 years who were free of diabetes mellitus and chronic kidney disease. Compared to those with cystatin C in the lowest quartile (quartile 1), the multivariate odds ratio (OR) of prediabetes among those in the highest quartile (quartile 4) was 2.08 (95% confidence interval [CI], 1.09 to 3.97; P for trend=0.02). The interesting point was that an inverse association was observed between cystatin C and prediabetes in quartile 2 (OR, 0.58; 95% CI, 0.37 to 0.89). In subgroup analysis, this inverse association in quartile 2 was significant in men and other race-ethnicities. In this study, the relative risk of subjects in the group with the fourth serum cystatin C levels (fourth=1.0 mg/L) for the presence of diabetic conditions was significantly decreased compared to the lowest group (first <0.8 mg/L) in the multivariable model (OR, 0.61; 95% CI, 0.39 to 0.97; P=0.037). Furthermore, this inverse association was also significant in men (OR, 0.48; 95% CI, 0.26 to 0.88; P=0.019). These results are compatible with the aforementioned study [6] but the reason for inverse association remains unclear.
Second, specific conditions such as severe anemia and diseases that change erythrocyte lifespan should be excluded. HbA1c has been proposed as a diagnostic tool to identify people with undiagnosed diabetes or those who are at risk of diabetes [8]. The HbA1c test is a very attractive test for the diagnosis of diabetes and prediabetes because it is easy, reproducible, and reflects the mean blood glucose levels over a period of time [8,9]. However, the HbA1c is affected not only by age and race but also by various diseases such as anemia, liver cirrhosis, and chronic kidney disease [10]. Analyzing the patients without diseases that can potentially affect HbA1c level would be more appropriate to evaluate the association between cystatin C and prevalence of diabetic conditions defined by HbA1c levels.

NOTES

CONFLICTS OF INTEREST: No potential conflict of interest relevant to this article was reported.

REFERENCES

1. Sarnak MJ, Katz R, Stehman-Breen CO, Fried LF, Jenny NS, Psaty BM, Newman AB, Siscovick D, Shlipak MG. Cardiovascular Health Study. Cystatin C concentration as a risk factor for heart failure in older adults. Ann Intern Med 2005;142:497-505.
PubMed 
2. Servais A, Giral P, Bernard M, Bruckert E, Deray G, Isnard Bagnis C. Is serum cystatin-C a reliable marker for metabolic syndrome? Am J Med 2008;121:426-432.
Article  PubMed 
3. Shankar A, Teppala S. Relationship between body mass index and high cystatin levels among US adults. J Clin Hypertens (Greenwich) 2011;13:925-930.
PubMed  PMC 
4. Donahue RP, Stranges S, Rejman K, Rafalson LB, Dmochowski J, Trevisan M. Elevated cystatin C concentration and progression to pre-diabetes: the Western New York study. Diabetes Care 2007;30:1724-1729.
PubMed 
5. Sahakyan K, Lee KE, Shankar A, Klein R. Serum cystatin C and the incidence of type 2 diabetes mellitus. Diabetologia 2011;54:1335-1340.
PubMed  PMC 
6. Sabanayagam C, Wong TY, Xiao J, Shankar A. Serum cystatin C and prediabetes in non-obese US adults. Eur J Epidemiol 2013;28:311-316.
PubMed 
7. Sim EH, Lee HW, Choi HJ, Jeong DW, Son SM, Kang YH. The association of serum cystatin C with glycosylated hemoglobin in Korean adults. Diabetes Metab J 2016;40:62-69.
PubMed 
8. American Diabetes Association. Classification and diagnosis of diabetes. Diabetes Care 2015;38(Suppl 1):S8-S16.
PMC 
9. International Expert Committee. International Expert Committee report on the role of the A1C assay in the diagnosis of diabetes. Diabetes Care 2009;32:1327-1334.
PubMed  PMC 
10. Hare MJ, Shaw JE, Zimmet PZ. Current controversies in the use of haemoglobin A1c. J Intern Med 2012;271:227-236.
PubMed 


ABOUT
BROWSE ARTICLES
FOR CONTRIBUTORS
Editorial Office
101-2104, Lotte Castle President, 109 Mapo-daero, Mapo-gu, Seoul 04146, Korea​
Tel: +82-2-714-9064    Fax: +82-2-714-9084    E-mail: diabetes@kams.or.kr                

Copyright © 2022 by Korean Diabetes Association.

Developed in M2PI

Close layer