Long-term glycemic variability and the risk of mortality in diabetic patients receiving peritoneal dialysis

Background The large amount of glucose in the dialysate used in peritoneal dialysis (PD) likely affects the glycemic control. The aim of this study was to investigate the association between HbA1c variability, as a measure of long-term glycemic variability, and the risk of all-cause mortality in diabetic patients with PD. Methods 325 patients with diabetes and ESRD were followed (2008-2018) in the Swedish Renal Registry. Patients were separated in seven groups according to level of HbA1c variability. The group with the lowest variability was denoted the reference. The ratio of the standard deviation (SD) to the mean of HbA1c, HbA1c (SD)/HbA1c (mean), i.e. the coefficient of variation (CV), was defined as HbA1c variability. Hazard ratios (HR) and 95% confidence intervals (CI) were examined using Cox regression analyses. Results During follow-up, 170 (52%) deaths occurred. The highest mortality was among patients with the second highest HbA1c variability, CV >= 2.83 [n = 44 of which 68% patients died]. In the multivariate analyses where lowest HbA1c variability (CV<0.51) was used as the reference group, HbA1c CV 2.83-4.60 (HR 3.15, 95% CI 1.78-5.55; p<0.001) and CV> 4.6 (HR 2.48, 95% CI 1.21-5.11; p = 0.014) were associated with increased risk of death. Conclusion The high risk of all-cause mortality in patients with diabetes and PD increased significantly with elevated HbA1c variability, as measure of long-term glycemic control. This indicates that stable glycemia is associated with an improvement of survival; whereas more severe glycemic fluctuations, possibly caused by radical changes in dialysis regimes or peritonitis, are associated with a higher risk of mortality in diabetic patients with PD.