Objective: To determine if the improvement in inpatient glycaemic control observed with basal-bolus insulin (BBI) over sliding-scale insulin (SSI) in the formal study setting translates to routine clinical conditions. Design, setting and patients: Cross-sectional study in which capillary blood glucose levels (BGLs) were prospectively measured four times daily for up to 8 days in 124 patients with type 2 diabetes admitted to a tertiary teaching hospital and treated with BBI between November 2008 and May 2010. Data from the BBI treatment group were compared with retrospective data from 96 patients treated with SSI between June 2001 and May 2006. Main outcome measures: Mean daily BGL; independent effect of insulin regimen on mean daily BGL. Results: Mean baseline BGL was not significantly different in patients receiving BBI and SSI (mean ±SD, 11.3 ± 4.1 v 10.6 ± 4.3mmol/L; P = 0.23). After the first full day of therapy, mean daily BGL for patients receiving BBI was 1.6 ± 3.7mmol/L lower than baseline BGL, and it remained 1.6-2.4mmol/L lower than baseline throughout the study (P < 0.001). In contrast, there was no significant change in BGL for patients receiving SSI. Random effects regression analysis indicated that BBI was associated with a significantly lower mean daily BGL than SSI, independent of other variables (P < 0.001). The incidence of hypoglycaemia (BGL < 4mmol/L) was significantly greater in patients receiving BBI than SSI (3.3% v 1.4%; P <0.001), but there was no significant difference for severe hypoglycaemia (BGL < 2.8mmol/L) (0.3 v 0.5%; P=0.3). Conclusions: Under routine clinical conditions, BBI is effective and safe across a range of patients and appears to be superior to SSI. Clinical improvements reflected those seen in a strict formal study setting.