In Vivo Relationship Between Insulin Clearance and Action in Healthy Subjects and IDDM Patients

The relationship between plasma clearance rate of insulin (PCR) and insulin-stimulated glucose disposal was investigated in 15 healthy subjects and 30 insulin-dependent diabetes mellitus (IDDM) patients with the sequential euglycemic (5 mMj clamp technique (insulin infusion rates of 0.5,1, 2, and 5 mU · kg⁻¹ · min⁻¹ in 2-h steps). In IDDM patients, insulin-stimulated glucose disposal was decreased at low insulinemia (steps 1–3), whereas at maximal insulinemia (step 4), insulin action was normal. In the healthy subjects, strong positive correlations were found for PCR versus steady-state glucose infusion rate (SSGIR): r = 0.71 (P < 0.005), 0.72 (P < 0.005), 0.72 (P < 0.005), and 0.78 (P < 0.001) for steps 1–4, respectively. In contrast, in the IDDM patients, no relationship was observed: r = 0.01, −0.03, 0.06, and 0.01 (NS) for steps 1–4, respectively. In univariate analyses of PCR, no differences were found between patient subgroups with values for percentage of tracer binding below or above 5% or insulin-antibody-binding capacities and equilibrium constants below or above the median. In multiple regression models, adjusting for insulin antibodies, preceding glycemic control (HbA₁ or fructosamine), and duration of IDDM, correlations for PCR versusSSGIR remained nonsignificant. In conclusion, insulin action is correlated to insulin clearance in healthy subjects, suggesting a functional relationship from an in vivo perspective. No such relationship was present in patients with IDDM, even after adjusting for insulin antibodies, precedingglycemic control, and duration of IDDM.