Too Much, Too Little Glucose Risky in Diabetics on Dialysis

PHILADELPHIA – Poor glycemic control is associated with decreased survival in diabetes patients on maintenance hemodialysis, according to a study presented at Kidney Week 2011.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh of the Harbor-UCLA Medical Center in Torrance, Calif.

Although some guidelines, such as those from the National Kidney Foundation Kidney Disease Outcomes Quality Initiative, recommend that diabetic dialysis patients follow the American Diabetes Association targets for glycemic control (hemoglobin A_1c less than 7%), "there is no consistent evidence to support these targets in dialysis patients," Dr. Kalantar-Zadeh said, noting that recent studies with different methodologies have reached opposing conclusions.

To determine the predictive value of glycemic control on mortality, Dr. Kalantar-Zadeh and his colleagues evaluated the association between HbA_1c and random serum glucose and survival in a large, contemporary cohort of diabetes patients treated at DaVita dialysis clinics from July 2001 to June 2006 with follow-up through June 2007.

Of 164,789 hemodialysis patients, the investigators identified 54,757 with diabetes for whom HbA_1c data were available, and analyzed death hazard ratios according to HbA_1c values and serum glucose levels, Dr. Kalantar-Zadeh explained. The adjusted all-cause death hazard ratio for baseline HbA_1c increments of 8.0%-8.9%, 9.0%-9.9%, and 10% or greater, respectively, were 1.06, 1.05, and 1.19, compared with a reference HbA_1c value of 7.0%-7.9%; the respective all-cause death hazard ratios for time-averaged HbA_1c were 1.11, 1.36, and 1.59, he said, noting that "a similarly consistent increase in cardiovascular mortality" was also observed.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh.

In fully adjusted models, decreased survival was also directly associated with time-averaged HbA_1c levels in the low range, with all-cause-death hazard ratios of 1.05, 1.08, and 1.35, respectively, for baseline HbA_1c values of 6.0-6.9%, 5.0-5.9%, and less than 5%, compared with 7.0-7.9%, Dr. Kalantar-Zadeh said. Further, the adjusted all-cause-death hazard ratios for time-averaged blood glucose levels of 175-199 mg/dL, 200-249 mg/dL, 250-299 mg/dL, and 300 mg/dL or higher were 1.03, 1.14, 1.30, and 1.66, respectively, compared with the reference range of 150-175 mg/dL.

The results are limited by the fact that HbA_1c levels are known to significantly underestimate glycemic control in hemodialysis patients, Dr. Kalantar-Zadeh acknowledged at the meeting, sponsored by the American Society of Nephrology. Also, "the information on comorbidity in our study was limited to that obtained from Medical Evidence Form 2728, in which comorbid conditions are significantly underestimated," he said. Lastly, "the study data did not include information on diabetes medication used at home or treatment adherence."

Limitations notwithstanding, the findings indicate that poor glycemic control (defined as HbA_1c of 8% or greater or a serum glucose level of 200mg/dL) is associated with death in diabetes patients on maintenance hemodialysis, and, unlike most diabetic patients, "those with kidney failure do not benefit from HbA_1c levels lower than 7%," Dr. Kalantar-Zadeh said. It appears that the most beneficial percentage is somewhere inside 6-8% in this patient population, "although controlled clinical trials to target HbA_1c at 6-8% are needed to determine the optimal range," he concluded.

Dr. Kalantar-Zadeh disclosed financial relationships with Abbott, Amgen, DaVita, Fresenius, Otsuka, Shire, Vifor, the National Institutes of Health, and the National Kidney Foundation. The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.

PHILADELPHIA – Poor glycemic control is associated with decreased survival in diabetes patients on maintenance hemodialysis, according to a study presented at Kidney Week 2011.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh of the Harbor-UCLA Medical Center in Torrance, Calif.

Although some guidelines, such as those from the National Kidney Foundation Kidney Disease Outcomes Quality Initiative, recommend that diabetic dialysis patients follow the American Diabetes Association targets for glycemic control (hemoglobin A_1c less than 7%), "there is no consistent evidence to support these targets in dialysis patients," Dr. Kalantar-Zadeh said, noting that recent studies with different methodologies have reached opposing conclusions.

To determine the predictive value of glycemic control on mortality, Dr. Kalantar-Zadeh and his colleagues evaluated the association between HbA_1c and random serum glucose and survival in a large, contemporary cohort of diabetes patients treated at DaVita dialysis clinics from July 2001 to June 2006 with follow-up through June 2007.

Of 164,789 hemodialysis patients, the investigators identified 54,757 with diabetes for whom HbA_1c data were available, and analyzed death hazard ratios according to HbA_1c values and serum glucose levels, Dr. Kalantar-Zadeh explained. The adjusted all-cause death hazard ratio for baseline HbA_1c increments of 8.0%-8.9%, 9.0%-9.9%, and 10% or greater, respectively, were 1.06, 1.05, and 1.19, compared with a reference HbA_1c value of 7.0%-7.9%; the respective all-cause death hazard ratios for time-averaged HbA_1c were 1.11, 1.36, and 1.59, he said, noting that "a similarly consistent increase in cardiovascular mortality" was also observed.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh.

In fully adjusted models, decreased survival was also directly associated with time-averaged HbA_1c levels in the low range, with all-cause-death hazard ratios of 1.05, 1.08, and 1.35, respectively, for baseline HbA_1c values of 6.0-6.9%, 5.0-5.9%, and less than 5%, compared with 7.0-7.9%, Dr. Kalantar-Zadeh said. Further, the adjusted all-cause-death hazard ratios for time-averaged blood glucose levels of 175-199 mg/dL, 200-249 mg/dL, 250-299 mg/dL, and 300 mg/dL or higher were 1.03, 1.14, 1.30, and 1.66, respectively, compared with the reference range of 150-175 mg/dL.

The results are limited by the fact that HbA_1c levels are known to significantly underestimate glycemic control in hemodialysis patients, Dr. Kalantar-Zadeh acknowledged at the meeting, sponsored by the American Society of Nephrology. Also, "the information on comorbidity in our study was limited to that obtained from Medical Evidence Form 2728, in which comorbid conditions are significantly underestimated," he said. Lastly, "the study data did not include information on diabetes medication used at home or treatment adherence."

Limitations notwithstanding, the findings indicate that poor glycemic control (defined as HbA_1c of 8% or greater or a serum glucose level of 200mg/dL) is associated with death in diabetes patients on maintenance hemodialysis, and, unlike most diabetic patients, "those with kidney failure do not benefit from HbA_1c levels lower than 7%," Dr. Kalantar-Zadeh said. It appears that the most beneficial percentage is somewhere inside 6-8% in this patient population, "although controlled clinical trials to target HbA_1c at 6-8% are needed to determine the optimal range," he concluded.

Dr. Kalantar-Zadeh disclosed financial relationships with Abbott, Amgen, DaVita, Fresenius, Otsuka, Shire, Vifor, the National Institutes of Health, and the National Kidney Foundation. The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.

PHILADELPHIA – Poor glycemic control is associated with decreased survival in diabetes patients on maintenance hemodialysis, according to a study presented at Kidney Week 2011.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh of the Harbor-UCLA Medical Center in Torrance, Calif.

Although some guidelines, such as those from the National Kidney Foundation Kidney Disease Outcomes Quality Initiative, recommend that diabetic dialysis patients follow the American Diabetes Association targets for glycemic control (hemoglobin A_1c less than 7%), "there is no consistent evidence to support these targets in dialysis patients," Dr. Kalantar-Zadeh said, noting that recent studies with different methodologies have reached opposing conclusions.

To determine the predictive value of glycemic control on mortality, Dr. Kalantar-Zadeh and his colleagues evaluated the association between HbA_1c and random serum glucose and survival in a large, contemporary cohort of diabetes patients treated at DaVita dialysis clinics from July 2001 to June 2006 with follow-up through June 2007.

Of 164,789 hemodialysis patients, the investigators identified 54,757 with diabetes for whom HbA_1c data were available, and analyzed death hazard ratios according to HbA_1c values and serum glucose levels, Dr. Kalantar-Zadeh explained. The adjusted all-cause death hazard ratio for baseline HbA_1c increments of 8.0%-8.9%, 9.0%-9.9%, and 10% or greater, respectively, were 1.06, 1.05, and 1.19, compared with a reference HbA_1c value of 7.0%-7.9%; the respective all-cause death hazard ratios for time-averaged HbA_1c were 1.11, 1.36, and 1.59, he said, noting that "a similarly consistent increase in cardiovascular mortality" was also observed.

Not only does too much glucose increase the risk of all-cause and cardiovascular mortality in this patient population, too little does as well, according to Dr. Kamyar Kalantar-Zadeh.

In fully adjusted models, decreased survival was also directly associated with time-averaged HbA_1c levels in the low range, with all-cause-death hazard ratios of 1.05, 1.08, and 1.35, respectively, for baseline HbA_1c values of 6.0-6.9%, 5.0-5.9%, and less than 5%, compared with 7.0-7.9%, Dr. Kalantar-Zadeh said. Further, the adjusted all-cause-death hazard ratios for time-averaged blood glucose levels of 175-199 mg/dL, 200-249 mg/dL, 250-299 mg/dL, and 300 mg/dL or higher were 1.03, 1.14, 1.30, and 1.66, respectively, compared with the reference range of 150-175 mg/dL.

The results are limited by the fact that HbA_1c levels are known to significantly underestimate glycemic control in hemodialysis patients, Dr. Kalantar-Zadeh acknowledged at the meeting, sponsored by the American Society of Nephrology. Also, "the information on comorbidity in our study was limited to that obtained from Medical Evidence Form 2728, in which comorbid conditions are significantly underestimated," he said. Lastly, "the study data did not include information on diabetes medication used at home or treatment adherence."

Limitations notwithstanding, the findings indicate that poor glycemic control (defined as HbA_1c of 8% or greater or a serum glucose level of 200mg/dL) is associated with death in diabetes patients on maintenance hemodialysis, and, unlike most diabetic patients, "those with kidney failure do not benefit from HbA_1c levels lower than 7%," Dr. Kalantar-Zadeh said. It appears that the most beneficial percentage is somewhere inside 6-8% in this patient population, "although controlled clinical trials to target HbA_1c at 6-8% are needed to determine the optimal range," he concluded.

Dr. Kalantar-Zadeh disclosed financial relationships with Abbott, Amgen, DaVita, Fresenius, Otsuka, Shire, Vifor, the National Institutes of Health, and the National Kidney Foundation. The study was supported by the National Institute of Diabetes and Digestive and Kidney Diseases.