Post-dialysis serum osmolality as a predictor of interdialytic weight gain in diabetic and non-diabetic hemodialysis patients: a cross-sectional study.

Background: Excessive interdialytic weight gain (IDWG) in hemodialysis is associated with high mortality. Limited evidence suggests that diabetes (DM) may exacerbate IDWG. We aimed to investigate whether the presence of diabetes and diabetes control have an effect on IDWG.

Methods: Diabetic and non-diabetic hemodialysis patients were included in the study. Blood samples were drawn at the end of the midweek dialysis session and just before the next session to measure blood urea nitrogen, creatinine, sodium, glucose, serum osmolality, and copeptin levels. IDWG was calculated, and patients were categorized based on their diabetes control status and IDWG.

Results: Eighty-six hemodialysis patients (33 with DM, 53 without DM) were included in the study. Mean age was 52.4 years. IDWG and serum copeptin levels of diabetic and non-diabetic patients were not different but post-dialytic osmolality, HbA1c and blood glucose were higher in diabetics. While the post-dialytic osmolality of patients with an IDWG > 3 kg was higher than that of patients with an IDWG of < 3 kg, HbA1c and blood sugar levels were not different. Regression analysis involving copeptin, Na, HbA1c, osmolality, glucose, and interdialytic blood glucose revealed only osmolality significantly affected IDWG (p = 0.006). For every 10 mmol increase in osmolality, IDWG increased by 0.5 kg. Copeptin, Na, HbA1c, glucose, and interdialytic blood glucose had no significant impact on IDWG.

Conclusions: In conclusion, this study highlights the importance of monitoring post-dialysis serum osmolality in hemodialysis patients, as it appears to be a significant factor in determining IDWG independent of the presence of DM.