Researchers evaluated the association between Retinol Binding Protein 4 (RBP4) and IR in hemodialysis subjects (HD). They also assessed how circulating RBP4 could be influenced by kidney transplant or different dialytic techniques.

Insulin resistance (IR) is common in patients with chronic kidney disease (CKD) and it often occurs in early stages of the renal impairment (glomerular filtration rate < 60 mL/min).

IR is defined by normal fasting serum glucose associated with high serum insulin levels, a state that results in type 2 diabetes when the increased insulin secretion is no longer able to compensate for impaired peripheral insulin responsiveness.

IR has a particularly relevant clinical impact in End Stage Renal Disease (ESRD) because it adds independent cardiovascular risk in patients who are rated as having an inherent increased cardiovascular (CV) risk and 10-time higher mortality for CV events than the general population.

As yet, the mechanisms underlying IR in CKD are far from being fully understood. Possible culprits include low tolerance to physical activity, sedentary life style, toxins no longer cleared by the failing kidneys, and an endocrine dysfunction of adipose tissue

RBP4 serum levels were evaluated in HD (n = 16) and matched healthy controls (C; n = 16). RBP4 and glucose transporter type 4 (GLUT4) mRNA expressions were also determined in adipose tissue.

Circulating RBP4 was evaluated after kidney transplant (n = 7) and in hemodialysis patients (n = 10) enrolled in a cross-over study treated with standard bicarbonate dialysis (BD) or hemodiafiltration (HDF).

HOMA index (P < 0.05) and serum RBP4 (P < 0.005) were higher in HD compared to C. RBP4 levels positively correlated with fasting serum glucose (P < 0.05).

RBP4 mRNA was lower in HD compared to C (P < 0.05) and positively correlated with kidney function (P < 0.05) and GLUT4 mRNA (P < 0.001). Transplant or HDF reduced circulating RBP4 (P < 0.01 and P < 0.05, resp.).

Study results demonstrate that IR is associated with high circulating RBP4 and that suppressed RBP4 adipose tissue expression is accompanied by reduced GLUT4 expression in HD. Renal transplantation or HDF are effective in lowering serum RBP4 levels.