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Background

End stage renal disease (ESRD) patients on renal replacement therapy (RRT) with diabetes mellitus (DM) have a higher mortality rate and an increase prevalence of vitamin D deficiency compared to those without DM. It is still debated if vitamin D deficiency is a risk factor or a prognostic marker for mortality in these patients. This study investigated the prevalence of vitamin D deficiency and its impact on all-cause mortality in HD patients with DM.

Methods

Our prospective non-interventional cohort study included 600 patients on hemodialysis therapy (HD) (median aged 56, interquartile range (19) years, 332 (55.3%) males) recruited from 7 HD centers, from all main geographical regions of Romania. The prevalence of DM was 15.3%. They were then followed regarding: dialysis duration, dialysis efficiency, renal anemia, CKD-MBD, inflammatory status and comorbidities: coronary artery disease (CAD), peripheral vascular disease (PVD) and stroke. The deficiency of 25-OH vitamin D was defined as a value lower than12 ng/mL.

Results

Patients were followed for 3 years. The overall 3 year mortality was 25.5% (153 individuals), being higher in patients with DM as compared to those without DM (33.7% vs. 24.0%; P = 0.049). The time-related prognosis was also influenced by the presence of DM, at the survival analysis resulting in a HR of 1.52 [1.03 to 2.26] 95% CI, P = 0.037, for death in dialyzedpatients with DM. In DM patients, 25-OH vitamin D deficiency was significantly higher(37.0% compared to 24.0%, P = 0.009). Furthermore, in patients with DM we observed ashorter dialysis duration (2 vs. 3 years, P<0.001) and a lower intact parathyroid hormone(iPTH) (258.0 pg/ml vs. 441.9 pg/ml, P = 0.002). Regarding the presence of comorbidities atthe inclusion in the study, the presence of diabetes in dialyzed patients was associatedwith increased prevalence of CAD (87.0% vs. 58.1%, P<0.001), PVD (67.4% vs. 17.3%,P<0.001) and history of stroke (29.3% vs. 14.0%, P<0.001). In patients with DM the presenceof 25-OH vitamin D deficiency increased the probability of death (50.0% vs. 24.1%;P = 0.011). In multiple Cox proportional hazards analysis, vitamin D deficiency remained anindependent predictor for mortality in dialysis patients with DM (HR = 1.71, 95% CI 1.21 to2.43, P = 0.003). In the same time, multiple Cox proportional hazards analysis showed thatage (HR = 1.02 per one year increase, P = 0.004), CAD (HR = 1.55, P = 0.046) and PVD(HR = 1.50, P = 0.029) were independent predictors for mortality in dialysis patients withDM.

Conclusions

ESRD patients with DM treated with HD have a higher overall mortality than non-DM patients. Vitamin D deficiency is significantly more prevalent in HD patients with DM. Low 25- OH vitamin D levels were associated with increased all-cause mortality in these patients. According to our data, in HD patients with DM, screening for vitamin D deficiency (and its correction) should be mandatory for an optimal risk reduction strategy.