Insulin resistance is frequently observed in critical illness. It can be quantified by the expensive and time-consuming euglycaemic hyperinsulinaemic clamp technique (M-value) and calculated indices of insulin resistance (Quantitative Insulin Sensitivity Check Index; QUICKI and Homeostasis Model Assessment; HOMA) with lower costs and efforts. We performed an observational study to assess the reliability of QUICKI and HOMA to evaluate insulin resistance in critically ill patients compared with the current gold standard method, the euglycaemic hyperinsulinaemic clamp technique.

Insulin resistance was measured in 30 critically ill medical patients by the euglycaemic hyperinsulinaemic clamp technique (M-value) as well as calculated using QUICKI and HOMA. Correlations between the M-values as well as QUICKI and HOMA were assessed by means of the Pearson’s correlation coefficient.

M-value, QUICKI and HOMA indicated insulin resistance in all 30 patients. However, both indices QUICKI and HOMA did not correlate with the M-values in our patients (r2 = 0.008 and 0.0005, respectively). A significant negative correlation was found between the M-value and the severity of illness assessed by the APACHE (Acute Physiology and Chronic Health Evaluation) III score (r2 = 0.16; P < 0.05). In contrast, neither HOMA nor QUICKI correlated with the APACHE III score (r2 = 0.034 and 0.033, respectively).

Although QUICKI and HOMA indicated insulin resistance in the critically ill medical patients, both indices did not correlate with the M-value. Therefore, the euglycaemic hyperinsulinaemic clamp technique remains the gold standard for estimating insulin resistance in critically ill patients.