Glycaemia influences glucose metabolism in sepsis during hyperinsulinemic clamp

Objectives

The optimal glycaemia in critically ill is not known. We investigated glucose metabolism in septic patients during hyperglycaemic clamp.

Patients and methods

In 10 non-diabetic stable septic patients on mechanical ventilation with baseline glycaemia >6mmol/l and continuous insulin infusion, two hyperinsulinaemic clamps (target insulinaemia 250 U/l) were performed after 8 h of no caloric intake. Target glycaemia was 5 mmol/1 (step 1) and 10 mmol/1 (step 2) respectively. Glucose uptake was calculated as the amount of glucose per time needed to maintain target glycaemia. Glucose oxidation was calculated from indirect calorimetry and urinary nitrogen losses. Values are provided as means ± SD, paired T test was used for statistical analysis and P < 0.05 was considered significant.

Results

Glucose uptake was at step 1 significantly lower than at step 2 (3.9 ± 2.5 mg/kg/min and 6.9 ± 1.93 mg/kg/min, respectively; P < 0.001). Glucose oxidation was also significantly lower at step 1 (2.4 ± 1.38 mg/kg/min and 4.46 ± 1.65 mg/kg/min, respectively; P < 0.01). Energy expenditure did not change (2280 ± 418 kcal/ 24 h and 2235 ± 216 kcal/24 h, respectively).

Conclusion

During hyperinsulinaemic clamp in sepsis glucose uptake and oxidation depend on glycaemia. Higher glycaemia may be beneficial in terms of higher glucose uptake and oxidation which is not accompanied by higher energy expenditure suggesting the suppression of catabolism.