INTRODUCTION: Hyperglycaemia has been shown to be detrimental in severely ill patients. Prospective randomized controlled trials in ICU patients demonstrated the benefit of near-normoglycaemia in reducing morbidity and mortality. Recommendations of professional societies (e.g., the American Diabetes Association) on glycaemic control in hospitalised patients have recently been published. It was therefore of interest to assess whether glycaemic control of diabetic subjects in our hospital adhered to these guidelines. No recent data are available on the glycaemic control of hospitalised diabetic patients in Switzerland. METHODS: Medical records of 580 hospitalised patients with type 1 and type 2 diabetes (290 from 2002, 290 from 2005) were extracted from the internal data base of the University Hospital Basel. The selection was based on the charts of successive admissions each month of the year. From these 290 records, 100 records were from the medical and surgical wards, respectively, and 30 from the medical ICU (MICU), 30 from the surgical ICU (SICU) and 30 from the coronary care unit (CCU), respectively. Thereby, the quality of glycaemic control was assessed within and between the wards. RESULTS: HbA1c of all diabetic patients with available measurements was 7.6 +/- 1.8% (mean +/- SD). HbA1c in medical wards was higher in 2005 than in 2002 (8.5 +/- 1.9% vs 7.5 +/- 2.8%; p = 0.014), and higher compared to surgical wards (8.5 +/- 1.9 % vs 6.7 +/- 1.1%; p textless0.0001). On admission 60% of the plasma glucose concentrations (PGC) in medical and surgical wards were above the recommended limit of 8 mmol/l (10.8 +/- 7.5 mmol/l); in 63% of the measurements in the MICU, SICU and CCU the values were above 6.8 mmol/l. In 2005, PGC in medical wards on admission was higher than in surgical wards (13.5 +/- 9.9 vs 9.4 +/- 9.9 mmol/l, p textless0.0001); in the MICU PGC was lower than in the SICU (9.7 +/- 1.5 vs 19.5 +/- 13.9 mmol/l; p textless0.0001) and in the CCU (9.7 +/- 1.5 vs 14.1 +/- 12.1 mmol/l; p = 0.038). PGC decreased on day 4 compared to admission in the medical wards in 2005 (p = 0.024). In the other wards PGC in 2005 failed to decrease during hospitalisation. CONC:LUSION: Most diabetic patients admitted to the hospital remained distinctly hyperglycaemic during hospitalisation. This was the case even in intensive care units, where equipment and staff for improved glycaemic control were available and where strict glycaemic control has recently been demonstrated to result in decreased complications, mortality and length of stay