Better glucose management can reduce mortality and morbidity in dialysis patients.
With 45% of dialysis patients presenting as a result of diabetic kidney disease or with comorbidity of diabetes, studies are examining blood sugar control as a means to improving outcomes for this large segment of the dialysis population.
The National Kidney Foundation (NKF) unveiled a new initiative towards this end with the publication of Kidney Disease Outcome Quality Initiative (KDOQI) Clinical Practice Guidelines and Clinical Practice Recommendations for Diabetes and Chronic Kidney Disease (CKD) earlier this year (Am J Kidney Dis. 2007;49 Suppl 2:S1-S182). Target blood sugar control, as measured by glycosylated hemoglobin (HgA1c), for CKD patients has been a subject of debate with the new KDOQI diabetes guidelines recommending a HgA1c goal of less than 7% for all CKD stages.
In contrast, the American College of Physicians’ newly issued guidance statement “Glycemic Control and Type 2 Diabetes Mellitus: The optimal HgA1c Targets” (Ann Intern Med. 2007;147:417-422) advises a more individually tailored approach to diabetes management. The statement says that “a hemoglobin A1c level less than 7% based on individualized assessment (‘risk for complications from diabetes, comorbidity, life expectancy, and patient preferences’) is a reasonable goal for many but not all patients.”
The statement called for “further research to assess the optimal level of glycemic control, particularly in the presence of comorbid conditions.” The evidence linking blood sugar control to slowed disease progression in early stages of CKD is clear, however. In the Diabetes Control and Complications Trial (DCCT) sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases, researchers found a 50% decrease in both development and progression of early diabetic kidney disease in patients who followed a regimen for controlling blood glucose levels.
Tipping the scale in favor of tighter blood sugar control are results of a three-year study of 23,618 MHD patients by Kalantar-Zadeh et al (Diabetes Care. 2007;30:1049-1055). In this study, MHD patients from a large U.S. dialysis provider database were examined retrospectively (2001-2004) with regard to HgA1c and survival. The authors note that “after adjusting for confounders (demographics, dialysis vintage, dose, comorbidity, anemia, and surrogates of malnutrition and inflammation), higher A1c values were associated with higher death rates.” As HgA1c rose above 6%, risk for all-cause mortality increased steadily.
What accounts for this finding of HgA1c attributable survival benefit compared with previous studies? Prior small sample size, ethnic exclusivity, and lack of identified confounders may have been reasons for past failure to detect benefit associated with glycemic control in dialysis patients.