A1c targets for type 1 diabetes, dialysis patients discussed at nephrology meeting

PHILADEPHIA—Tight glucose control appears beneficial in preventing kidney function decline in newly diagnosed type 1 diabetics, but not so helpful for diabetics who already have kidney failure, according to data presented at the annual meeting of the American Society of Nephrology.

In a study that was also published online by the New England Journal of Medicine, researchers used follow-up data from the Diabetes Control and Complications Trial (DCCT) to determine the effect of intensive glucose control on glomerular filtration rate (GFR). Patients in the six-year trial were randomly assigned to either three or more insulin daily injections with an A1c target under 6.05% (actual average A1c in the group was 7.3%) or one or two daily injections to prevent symptoms of hyper- and hypoglycemia. Over a median follow-up of 22 years, half as many patients in the intensive group developed impaired GFR or end-stage renal disease (24 patients vs. 46 and 8 vs. 16, respectively). Although the applicability to type 2 diabetes is uncertain, the researchers concluded that the results reinforce current recommendations to target an A1c of 7% in patients with type 1 diabetes.

However, diabetic patients who were already on dialysis had the lowest risk of death if they had higher A1cs, according to two other large studies presented at the conference. In an observational study from 2001 to 2007 of more than 50,000 dialysis patients with diabetes, researchers from the University of California Los Angeles found that the lowest mortality levels were associated with an A1c between 7.0% and 7.9%, with increases in mortality both above and below this level. Serum glucose levels between 150 mg/dL and 175 mg/dL were associated with the lowest mortality, with increases in mortality at higher and lower glycemic levels. “High is bad, but very low is not good either,” concluded study author Kamyar Kalantar-Zadeh, MD, PhD, FACP. “We need controlled trials to target certain ranges of A1c to verify these findings.”

It wasn't a controlled trial, but the international Dialysis Outcomes and Practice Patterns Study (DOPPS) showed similar results in data presented at the conference. It included more than 8,000 hemodialysis patients and also found a U-shaped association between A1c and mortality, with the lowest risk associated with A1c levels of 7% to 8%. All-cause mortality risk appeared to be greatest at A1c levels of 9% or greater and less than 5%, and a trend toward higher mortality risk was seen at levels below 7%.

The authors of the latter two studies noted that current National Kidney Foundation guidelines recommend the same A1c targets for patients with kidney disease as other diabetics: below 7%. However, Katherine R. Tuttle, MD, FACP, who moderated the press conference at which the results were announced, said new guidelines have been drafted that include revised recommendations for glycemic targets in patients with kidney disease. The guidelines will be released soon for public review, she said.