letter to the editor
Glycosylated hemoglobin, glycemic control, and mortality in hemodialyzed diabetic patients
Sciences, Tehran, Iran and 3Department of Internal Medicine and Nephrology, Iran University of Medical Sciences, Tehran, Iran Correspondence: M Rambod, Obesity Research Center, Research Institute for Endocrine Sciences, Shaheed Beheshti University of Medical Sciences, PO Box 19395-4763, Tehran, Iran. E-mail:
[email protected]
Kidney International (2007) 71, 1078. doi:10.1038/sj.ki.5002253
To the Editor: Recently, Williams et al.1 examined the association between hemoglobin A1c (HbA1c) with fasting plasma glucose and all-cause mortality. This is the first report with considerable samples size addressing the glycemic control in maintenance dialysis patients. Notwithstanding its relative novelty, some limitations may exist in the analyses of data and drawing conclusions. It would be interesting to study other potential determinants of HbA1c, especially since fasting plasma glucose has poor correlation (r2 ¼ 0.37). The authors did not clearly mention the role of other risk factors known to contribute to mortality in the general population, such as body mass index, exercise, and smoking habits. Many deaths in diabetic patients may be related to macrovascular events,2 hence, it would be reasonable to examine the association between HbA1c and death due to macrovascular events such as peripheral and cardio-vascular disease rather than all-cause mortality. The study did not report the unadjusted comparison of HbA1c levels between deceased and surviving patients before reporting multivariate analyses. The authors used HbA1c 6.5–7% as reference range. Although the foregoing range is usually used as the reference in the non-end-stage renal disease diabetic patients, it would be more appropriate to use receiver operating characteristic curve to find proper level of HbA1c discriminating survival and mortality to use in the hazard regression models of dialysis patients. Authors did not clarify which criteria were used for the diagnosis of type II diabetes.3,4 Whereas the authors cast doubt on the value of HbA1c as the life expectancy of red blood cells is about 60 days in end-stage renal disease patients, they could have used the same period of time for analyses. Finally, stratification, stepwise confounder adjustments, and checking the important interactions between suspected risk factors need to be examined. Acknowledging the above limitations does not guarantee the accuracy of conclusions, even when the analyses are not conducted properly. 1. Williams ME, Lacson Jr E, Teng M et al. Hemodialyzed type I and type II diabetic patients in the US: characteristics, glycemic control, and survival. Kidney Int 2006; 70: 1503–1509. 2. Home P. Contributions of basal and post-prandial hyperglycaemia to micro- and macrovascular complications in people with type 2 diabetes. Curr Med Res Opin 2005; 21: 989–998. 3. Expert Committee on the Diagnosis and Classification of Diabetes Mellitus. Report of the expert committee on the diagnosis and classification of diabetes mellitus. Diabetes Care 1997; 20: 1183–1196. 4. World Health Organization. Diabetes mellitus: report of WHO Study Group. World Health Organization: Geneva, 1985 Technical Report Ser. no. 727.
M Rambod1,2 and B Broumand2,3 1
Obesity Research Center, Research Institute for Endocrine Sciences, Shaheed Beheshti University of Medical Sciences, Tehran, Iran; 2Department of Nephrology and Kidney Transplantation, Iranian Academy of Medical
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Kidney International (2007) 71, 1076–1078
