Hyperglycemia in hospital inpatients without pre-existing diabetes is associated with increased mortality. However, the independent contribution of hyperglycemia to healthcare-associated infection (HAI), acute kidney injury (AKI), and stroke is unclear. To investigate the relationship between hyperglycemia and adverse clinical outcomes in hospital for patients with and without diabetes. Diabetes IN-hospital: Glucose and Outcomes (DINGO) was a 26-week (October 2019 - March 2020) prospective cohort study. Clinical and glucose data were collected up to the 14th day of admission. Primary stratification was by hyperglycemia, defined as ≥2 random capillary blood glucose (BG) measurements ≥11.1 mmol/L (≥200 mg/dL). Propensity weighting for nine clinical characteristics, was performed to allow interrogation of causality. To maintain the positivity assumption, patients with HbA1c > 12.0% were excluded and pre-hospital treatment not adjusted for. The Royal Melbourne Hospital, a quaternary referral hospital in Melbourne, Australia. Admissions with at least two capillary glucose values and length of stay >24 hours were eligible, with half randomly sampled. HAI, AKI, stroke, and mortality. Of 2,558 included admissions, 1,147 (45%) experienced hyperglycemia in hospital. Following propensity-weighting and adjustment, hyperglycemia in hospital was found to, independently of nine covariables, contribute an increased risk of in-hospital HAI (130 [11.3%] vs.100 [7.1%], adjusted odds ratio [aOR] 1.03, 95% confidence interval [95%CI] 1.01-1.05, p = 0.003), AKI (120 [10.5%] vs. 59 [4.2%], aOR 1.07, 95%CI 1.05-1.09, p < 0.001), and stroke (10 [0.9%] vs. 1 [0.1%], aOR 1.05, 95%CI 1.04-1.06, p < 0.001). In hospital inpatients (HbA1c ≤ 12.0%), irrespective of diabetes status and pre-hospital glycaemia, hyperglycemia increases the risk of in-hospital HAI, AKI, and stroke compared with those not experiencing hyperglycemia.