'Tight' glycaemic control in perioperative or critical ill patients may carry the risk of hypoglycaemia. However, a blood glucose target of 4.5–6.1 mmol/l has been shown to benefit critically ill, mainly postcardiothoracic surgery patients where, unusually, all patients were given glucose infusions from admission (200–300 g/24 hours). Of the 'tight' group, 5.2% had inconsequential hypoglycaemic episodes (blood glucose <2.2 mmol/l). The perceived risk of hypoglycaemia in starved patients receiving insulin to achieve 'tight' glycaemic control is a widespread concern. We report safety monitoring in our ongoing prospective, double-blind, randomised controlled study (the Does Additional Glucose Make A Difference? trial) investigating whether initial additional glucose infusion improves outcome in critical care patients receiving a 'tight' glycaemic control. Patients received 50% glucose or 0.9% NaCl at 20 ml/hour until full nutrition was taken. We monitored for excess hypoglycaemic episodes in our NaCl group. We set a 5% acceptable incidence of blood glucose <3.0 mmol/l and 0% for adverse consequences.

Hourly arterial line samples were tested by regularly calibrated Accu-check® (Roche Diagnostics) bedside monitors. Insulin (Actrapid®; Novo Nordisk), 50 U in 50 ml of 0.9% NaCl, was administered by continuous infusion and boluses according to an algorithm. The study period was the time that study infusions were given. Investigators remained blinded.

Complete data was obtained from 113 patients (63 and 50 in each group) of 127 who gave informed consent according to local medical ethics guidelines. No adverse incidents or deaths were recorded in patients with incomplete data. There were no differences between the groups in (group 1 [mean, SD], group 2 [mean, SD]): age (66.7, 14.9), (67.1, 12.7), body mass index (77.3, 16.2), (79.8, 12.4), APACHE II score (13.8, 12.2), SOPRA (30.4, 12.2), (33.3, 10.5), admission reason (87%, 92% cardiac surgery) or death in the ITU (3.2%, 2%).

Total hypoglycaemic (< 3.0 mmol/l) and hyperglycaemic (> 12.0 mmol/l) episodes (total hours of study period) and mean (SD) hours outside the prescribed range (4.5–6.1 mmol/l) for each patient during the study period are presented in Table 1.

Table 1
Full size table

Tight glycaemic control appears safe in patients receiving either 50% glucose or 0.9% NaCl at 20 ml/hour.