['To examine the occurrence of feed intolerance in critically ill patients with previously diagnosed type II diabetes mellitus (DM) who received prolonged gastric feeding.', 'Retrospective study in a level 3 mixed ICU.', 'All mechanically ventilated, enterally fed patients (n = 649), with (n = 118) and without type II DM (n = 531) admitted between January 2003 and July 2005.', 'Patients with at least 72 h of gastric feeding were identified by review of case notes and ICU charts. The proportion that developed feed intolerance was determined. All patient received insulin therapy.', 'The proportion of patients requiring gastric feeding for at least 72 h was similar between patients with and without DM (42%, 50/118, vs. 42%, 222/531). Data from patients with DM were also compared with a group of 50 patients matched for age, sex and APACHE II score, selected from the total non-diabetic group. The occurrence of feed intolerance (DM 52% vs. matched non-DM 50% vs. unselected non-diabetic 58%) and the time taken to develop feed intolerance (DM 62.6 +/- 43.8 h vs. matched non-DM 45.3 +/- 54.6 vs. unselected non-diabetic 50.6 +/- 59.5) were similar amongst the three groups. Feed intolerance was associated with a greater use of morphine/midazolam and vasopressor support, a lower feeding rate and a longer ICU length of stay.'] Is gastric feed intolerance increased in critically ill patients with type II diabetes mellitus?