Background Although hemoglobin A1c (HbA1c) has been widely used as a clinical assessment tool for outcome analyses related to glycemic control the relationship between HbA1c and average blood glucose (BG) specific to peritoneal dialysis (PD) patients with diabetes has not been characterized. the following HbA1c-BG equations: (1) BG (mg/dL)=24.1 + 28.6 × HbA1c – 12.2 × Albumin (R2adj=0.454) (2) BG = 55.3+ 28.8 × HbA1c-10.2 × Albumin ?3.3 × Hemoglobin (R2adj=0.457) (3) and BG =69.5 +28.7 × HbA1c- 10.1 × Albumin- 3.7 × Hemoglobin- 0.1 × Age+ Race/Ethnicity (?10.1 FCGR3A African-Americans ?5.4 other race/ethnicities; R2adj=0.457). All models showed greater explanatory power of BG variation than previously established HbA1c-BG equation models defined within non-PD cohorts (R2adj=0.446 for both the DCCT and the ADAG equations). Conclusions The association between HbA1c and BG in PD patients is different than that of patients with normal kidney function. Our analysis suggests that equations incorporating serum albumin and/or hemoglobin values better estimate the HbA1c-BG relationship in PD patients compared to equations using HbA1c alone. Keywords: Hemoglobin A1c blood glucose equation model glycemic control albumin hemoglobin peritoneal dialysis race Introduction Hemoglobin A1c (HbA1c) is a clinically important assessment tool for evaluating the association between glycemic control and outcomes in diabetic patients. Two widely used equations for converting HbA1c into mean blood glucose levels have included the one derived from Diabetes Control and Complications Trial (DCCT) (average glucose (mg/dl)=35.6 × HbA1c- 77.3) and the A1c-Derived Average Glucose (ADAG) study formula (average glucose (mg/dl)=28.7 × HbA1c – 46.7) which were defined in populations without underlying kidney disease [1 2 The ADAG group concluded that HbA1c is a reliable substitute for average blood glucose and that aside from analytic variation the only important determinant of the HbA1c is the preceding 3-month average glucose concentration. The rate of hemoglobin (Hb) glycation is determined by temperature serum pH Hb concentration blood glucose (BG) concentration and length of exposure to glucose . Given that dialysis patients have significantly altered Hb concentrations and pH levels the correlation between HbA1c and BG levels in dialysis patients is different than that of patients with normal renal function. Furthermore shortened erythrocyte life span Malotilate and accelerated erythropoesis due to erythropoiesis-stimulating agent use may further alter HbA1c levels in dialysis patients. Indeed HbA1c was found to underestimate glucose measurements compared to glycated albumin in diabetic patients on dialysis [4-6]. However HbA1c is still a widely used measure of chronic glycemic control in dialysis patients . Despite the increasing number of diabetic patients on dialysis Malotilate and the fact that serum albumin levels are lower in patients undergoing peritoneal dialysis (PD) HbA1c-BG equation formula specific to this population has not yet been derived. Furthermore the association between HbA1c and BG in PD patients may be different from hemodialysis (HD) patients given that the former group is exposed to higher dialysate glucose concentrations. In this study we sought to develop HbA1c-BG equation models specific for PD patients. Subjects and Methods Study Population The data were obtained from DaVita Inc. the second largest dialysis care provider in the United States with approximately 500 outpatient dialysis centers Malotilate and 40 0 patients across the country. The creation of this national dialysis patient cohort has been described previously [8-13] A 60-month prevalent cohort (July 2001 through Malotilate June 2006) of patients undergoing PD patients was studied. Demographic data and details of medical history were collected with information on age sex race and presence of diabetes. The study conformed to the Declaration of Helsinki and International Conference on Harmonization of Good Clinical Practice Guidelines. Patients receiving dialysis for less than 90 days those without diabetes; with missing values of albumin glucose Hb or HbA1c; and with <3 measurements for each of these laboratory measures were excluded from this analysis. We divided race/ethnicity into four groups: non-Hispanic white African-American.