Influence of insulin clearance to glucose tolerance in acutely ill severe patients: analysis with glucose clamp method by means of artificial pancreas
© BioMed Central Ltd 2003
Published: 3 March 2003
Acutely ill patients often have glucose intolerance (GI), which is one of the factors preventing appropriate nutritional support. However, mechanisms of GI are not clearly understood. Among the factors that influence GI, insulin sensitivity (IS) and insulin clearance (IC) are considered to be the important factors, because insulin is one of the most important factors which control glucose metabolism and insulin therapy is usually performed for patients with GI. We investigated glucose tolerance in terms of IS and IC in acutely ill severe patients by the glucose clamp method (GC) by means of a bedside-type artificial pancreas (STG-22: NIKKISO Corporation, Tokyo, Japan).
Thirty-one patients (27 patients had sepsis) in whom blood glucose levels were controlled by means of the artificial pancreas were investigated. First measurement of GC was performed in acute condition or within 3 days after admission for all the patients, and second measurement was done 1 week after the first measurement for 13 patients. GC was performed with clamped blood glucose level of 80 mg/dl and Insulin Infusion Rate (IIR) of 1.12 and 3.36 mU/kg per min. I1/I3 and M1/M3 indicate the blood insulin level (μU/ml) and glucose disposal rate: M value (mg/kg per min), when IIR is 1.12/3.36 mU/kg per min, respectively (normal value of M1: 5–10 mg/kg per min). M1/I1: (M1/I1 × 1000) was calculated as the parameter of IS (normal value of M1/I1: more than 50 mg/l per kg per min per μU). IC was calculated from the following formula: IC = (3.36–1.12) × 1000/(I3–I1) (normal value of IC: 10–15 ml/kg per min). Glucose tolerance was analyzed in terms of M1, IS (M1/I1), and IC.
1) The proportion of the patients who had M1 levels less than 5 mg/kg per min (GI), IS (M1/I1) less than 50 mg/l per kg per min per μU (insulin resistance), and IC more than 15 ml/kg per min (increased IC) were 66% (29/44), 27% (12/44), and 61% (27/44), respectively. 2) Among the patients with GI (n = 29), only 38% (11/29) of the patients had insulin resistance. Sixty-two percent (18/29) of the patients with GI had normal IS, and 83% of them (15/18) had increased IC (mean ± SD of IC, I1: 22 ± 3.8 ml/kg per min, 38.3 ± 9.5 μU/ml, n = 15). 3) Among the patients with normal glucose tolerance (n = 15), 93% (14/15) of them had normal IS. However, one patient had both insulin resistance (M1/I1 = 43.5 mg/l per kg per min per μU) and decreased IC (IC = 3.9 ml/kg per min, I1 = 131 μU/ml).
Interpretation and conclusions
1) IC was the important factor that influenced the glucose tolerance in acutely ill severe patients, although the mechanisms of the change of IC was unclear. 2) Sufficient insulin administration was considered to be necessary from the aspect of metabolic and nutritional control for those patients with increased IC.