Insulinogenic index in non-diabetics during haemodialysis

The aim of this study was to analyse whether the insulin to glucose relationship following an intravenous glucose load in non-diabetic patients delivered during haemodialysis was affected by extracorporeal clearance and whether this relationship could be determined by an abridged sampling protocol.

Studies were done during routine haemodialysis following the infusion of 0.5 g glucose per kilogram body mass. Extracorporeal effects were measured by online clearance (K(OCM)) and insulin clearance (K(I)). The insulin to glucose relationship was examined for a period of 1 h following the infusion of glucose. The integral response measured as the insulinogenic index (I(G)) was compared to the relationship between insulin and glucose concentrations measured for the whole period (k(IG)) as well as from only two samples taken at baseline and after 10 min (k(10)).

Eight non-diabetic haemodialysis patients (three females) with a dry body mass of 76.9 ± 18.2 kg completed the study. I(G) was 5.4 ± 4.4 U/mol and not different from normal reference values. A linear relationship providing characteristic slopes k(IG) was observed between arterial insulin and glucose levels. k(IG) was 6.1 ± 5.0 U/mol and not different from k(10) = 5.9 ± 4.8 U/mol measured after 10 min of glucose infusion and ongoing dialysis. I(G), k(IG) and k(10) were highly correlated (P < 0.0001), and k(10) showed substantial concordance (ρ(c) = 0.99) with I(G). Moreover, I(G), k(IG) and k(10) were independent of K(OCM) or K(I).

The insulin to glucose relationship is measurable within 10 min of glucose administration and unaffected by extracorporeal clearance. This could be helpful to characterize the insulin response to a glucose stimulus during haemodialysis.