Hindawi Publishing Corporation International Journal of Endocrinology Volume 2012, Article ID 687867, 6 pages doi:10.1155/2012/687867 Clinical Study Factors Associated with the Decline of Kidney Function Differ among eGFR Strata in Subjects with Type 2 Diabetes Mellitus Shu Meguro, 1 Masuomi Tomita, 2 Yusuke Kabeya, 2 Takeshi Katsuki, 2 Yoichi Oikawa, 2 Akira Shimada, 2 Toshihide Kawai, 1 Hiroshi Itoh, 1 and Yoshihito Atsumi 2 1 Nephrology, Endocrinology and Metabolism Division, Department of Internal Medicine, School of Medicine, Keio University, Tokyo 160-8582, Japan 2 Department of Internal Medicine, Saiseikai Central Hospital, Tokyo 108-0073, Japan Correspondence should be addressed to Shu Meguro, shumeg@z8.keio.jp Received 24 August 2012; Revised 30 November 2012; Accepted 30 November 2012 Academic Editor: Peter Rossing Copyright © 2012 Shu Meguro et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Introduction. There is no report about risk factors for renal deterioration according to the clinical stage, divided by the estimated glomerular filtration rate (eGFR) in type 2 diabetes. Materials and Methods. We evaluated the factors correlated with the annual eGFR decline in 1303 subjects with type 2 diabetes whose eGFR was ≥30 mL/min/1.73 m 2 . eGFR strata were defined by baseline eGFR value as follows: stratum 1: ≥90, stratum 2: ≥60, <90, and stratum 3: ≥30, <60. Results. The annual eGFR decline was 2.3 ± 5.4 mL/min/1.73 m 2 in overall subjects. Multiple linear regression analysis demonstrated that age, male sex, systolic blood pressure, logarithmically transformed albumin excretion rate (AER), eGFR strata, and hemoglobin concentration were significantly correlated with the annual eGFR decline. When stratified by eGFR, the factors that showed a significant correlation were different among eGFR strata. AER was significantly correlated with annual eGFR decline in all eGFR strata. Hemoglobin concentration showed a significant correlation only in the advanced eGFR stratum. Conclusion. The factors correlated with the annual eGFR decline were different among eGFR strata in type 2 diabetes mellitus, and hemoglobin concentration and AER were important factors for renal deterioration, especially in the advanced eGFR stratum. 1. Introduction Diabetic kidney disease is the leading cause of end-stage renal disease (ESRD), and the number of individuals requiring chronic dialysis or renal transplantation is still increasing in most countries [1]. Both urinary albumin excretion and esti- mated glomerular filtration rate (eGFR) are independently associated with the worsening of kidney function [2, 3]. We previously reported that a very high proportion of Japanese subjects with type 2 diabetes mellitus with stage 3 chronic kidney disease (CKD) progressed to stage 4 CKD within 3 years, and that the existence of albuminuria further accel- erated the clinical course [3]. Although the clinical course of the deterioration of kidney function might differ among study populations, another study from the United Kingdom reconfirmed a similar relation between albuminuria and eGFR [4]. We also found that hemoglobin concentration was a significant predictor of deterioration to CKD stage 4 [3]. Anemia is a common complication of chronic kidney dis- ease (CKD). In diabetes mellitus, anemia develops earlier and is more severe than in patients with renal impairment with other causes [5, 6]. Anemia in diabetes mellitus is known to be a risk factor for the development and progression of micro- and macrovascular complications of diabetes mellitus as well as increased mortality independent of the presence or severity of diabetic nephropathy [7]. A reduced hemoglobin concentration, even within the normal range, is associated with an increased risk of ESRD and death in subjects with chronic renal failure [8]. It was also reported that lower hemoglobin level was related to subsequent decline of kidney function in subjects with persistent macroalbuminuria [9] and also in those without albuminuria [10]. However, there is no report on the risk factors for decline of kidney function according to clinical stage, divided by eGFR. Especially, data on the GFR decline in subjects with type 2 diabetes mellitus whose GFR was less than 60 mL/min/1.73 m 2 are scarce