The relationship between inpatient hyperglycaemia and mortality is modified by baseline glycaemic status

AIMS: There is a well-established association between inpatient hyperglycaemia and mortality. However, evidence is inconsistent regarding whether this association is differential among those with and without type 2 diabetes mellitus (T2DM). Most studies are based on convenience samples or are unable to adjust for comorbidities. We examined whether the association between hyperglycaemia and 30-day mortality was modified by baseline glycaemic status. MATERIALS AND METHODS: This was a retrospective cohort study of 174,671 eligible hospitalized individuals between 2012 and 2015. Thirty-day mortality was assessed during the first inpatient stay up to 30 days post discharge. The adjusted association between hyperglycaemia and mortality was assessed with logistic regression models. Then, four interaction terms were entered into the model to assess if the association between hyperglycaemia and mortality differed by baseline glycaemic status. RESULTS: The multivariate model demonstrated a 2.18-fold risk of mortality associated with hyperglycaemia (odds ratio [OR] [95%CI]: 2.19 [2.08-2.31]). Adding the interaction terms between hyperglycaemia and baseline glycaemic status the ORs of 30-day mortality were 1.41 (1.25-1.60) in non-T2DM status, 1.32 (1.16-1.51) in pre-diabetes status and 1.30 (1.04-1.62) in unscreened status, as compared to T2DM status with hyperglycaemia. CONCLUSIONS: Hyperglycaemia is positively associated with mortality and both those without and with controlled T2DM are at highest risk. These findings may help medical staff identify potential increased risk of mortality upon hospital entry and discharge, and direct further research to assess how hyperglycaemia control and proactive deterioration prevention throughout the entire inpatient stay may prevent adverse outcomes.