To evaluate if type 2 diabetes mellitus (DM) constitutes a prognostic factor for death and severe disability in patients with aneurysm clipping after subarachnoid hemorrhage (ASH), in an Intensive Care Unit (ICU). This is a cohort study in patients who were admitted to the ICU between December-2009 and June-2010; 20 with DM (exposed group) and 40 without DM (non-exposed group). Mortality was quantified during ICU stay. At ICU discharge, severe disability was measured through the Glasgow Outcome Scale (category 2); and Glasgow Coma Scale was used to estimate the difference in consciousness level between ICU arrival and discharge. Descriptive statistics and Kaplan Meier survival curves were performed. Mean age was similar between groups (55.8 +/- 11 and 55.6 +/- 15 years, respectively, p = 0.40). A vegetative state was present in one patient without DM. The Glasgow Coma Scale score at ICU entry was 14.1 +/- 1.4 and at discharge, 12.0 +/- 3.6 in the exposed group (p = 0.01); and 13.9 +/- 2.0 us. 13.5 +/- 2.6, in the non-exposed group, respectively (p = 0.45). There were 3 deaths in patients with DM and 5, in patients without DM (p > 0.05); survival time was 12 (95%CI 7, 16) and 10 days (95%CI 7, 13), respectively. Mean glucose remained higher in patients who died at the ICU (p < 0.001). Hydrocephaly was present in 6 exposed patients and 2, non-exposed (p = 0.007). Additionally, 7 and 5 with and without DM, respectively registered a positive blood culture (p = 0.04). DM was not associated with higher mortality in ICU patients, but hyperglycemia was; thus, it is essential that the intensive care provider watches closely the glycemic control.