Serum insulin and insulin-like growth factor binding protein-1 levels in adult patients undergoing peritoneal dialysis.

It is known that serum insulin-like growth factor binding protein-1 (IGFBP-1) concentrations are inversely related to insulin levels both in healthy and diabetic subjects. The aim of the present study was to assess serum IGFBP-1 levels in a group of patients undergoing peritoneal dialysis (PD) and to evaluate their relationship with serum insulin concentrations. Thirty-five patients [19 males, 16 females; age (mean +/- SEM) 53.2 +/- 2.5 years; range 18-78; duration of continuous ambulatory peritoneal dialysis 33.1 +/- 6.0 months; Kt/V 2.00 +/- 0.05; normalized protein catabolic rate 1.00 +/- 0.05 g/kg/day] were studied. Nine patients were diabetics. In all patients, baseline IGFBP-1, insulin, and growth hormone (GH) levels were determined. Fasting IGFBP-1 levels were elevated in 19 (54%) patients and were normal in 16 patients. In all patients, high levels of serum insulin levels (> 25 microU/mL) were observed. Baseline IGFBP-1 levels were only slightly higher in diabetic patients (53.7 +/- 14.6 vs 40.5 +/- 8.2 micrograms/L,NS), however, serum levels of GH were similar in both groups (3.0 +/- 1.8 vs 2.9 +/- 0.5 microgram/L, NS). There was no correlation between fasting insulin and IGFBP-1 levels both in the whole group (r = 0.2; NS) and the diabetic (r = 0.2; NS) and nondiabetic (r = 0.3; NS) subgroups, despite high fasting insulin levels. We could only find a significant positive correlation between fasting glucose and IGFBP-1 levels in the diabetic group (r = 0.7, p < 0.05). Our data suggest that adult patients undergoing PD show hyperinsulinemia associated with normal or high serum IGFBP-1 levels. This suggests that insulin does not affect IGFBP-1 production in this group of patients. It could be explained, at least in part, by the insulin resistance present in uremia.