Diabet. Med. 29, e445–e448 (2012) Abstract Aim To study the length of stay and inpatient mortality of patients with diabetes who had an episode of hypoglycaemia in a non critical care setting at University Hospital Birmingham, UK. Methods Retrospective analysis of routinely available electronic data of 6374 admissions with a recording of either laboratory or point-of-care blood glucose value. Based on the lowest recorded blood glucose values, patients were categorized into a group without hypoglycaemia (> 3.9 mmol/l), a group with mild to moderate hypoglycaemia (2.3–3.9 mmol/l) and a group with severe hypoglycaemic (≤ 2.2 mmol/l). Length of stay and inpatient mortality were compared between the three groups, adjusting for age, gender, ethnicity, deprivation, admission type, use of insulin and modified Charlson co-morbidity score. Results There were 148 admissions (2.3%) with severe hypoglycaemia (≤ 2.2 mmol/l), 500 admissions (7.8%) with mild to moderate hypoglycaemia (2.2–3.9 mmol/l) and 5726 admissions with no recorded hypoglycaemic episode (> 3.9 mmol/l). After adjustment, length of stay, when compared with those without a recorded hypoglycaemic episode, was 1.51 (95% CI 1.35–1.68) times higher in the group with blood glucose values of 2.3–3.9 mmol/l and 2.33 (95% CI 1.91–2.84) higher in the group with blood glucose values ≤ 2.2 mmol/l. Adjusted odds ratio of inpatient mortality when compared with the group without hypoglycaemia was 1.62 (95% CI 1.16–2.27) in the group with blood glucose values of 2.3–3.9 mmol/l and 2.05 (95% CI 1.24–3.38) in the group with blood glucose values ≤ 2.2 mmol/l. Conclusion Hypoglycaemia is associated with increased length of stay and inpatient mortality. Whilst causative evidence is lacking, our data are consistent with the need to avoid hypoglycaemia in our current and continued approach for optimal glycaemic control in people with diabetes admitted to hospital.