The relationship between admission blood glucose levels and hospital mortality.

AIMS/HYPOTHESIS: The purpose of this study was to examine the relationship between blood glucose level (BGL) on admission with mortality rates among patients admitted to hospital through the Emergency Department.

METHODS

In a prospective observational study, BGLs were routinely measured on 6,187 consecutive patients requiring blood testing and admitted through the Emergency Department of a tertiary referral hospital. These measurements were matched against demographic data and hospital mortality rates.

RESULTS

Overall in-hospital mortality was 4.8%. Admission BGL was an independent predictor of mortality (HR 1.04 per 1 mmol/l increase, 95% CI 1.02-1.06, p=0.02). There was a significant interaction between diabetes status and increasing BGL on mortality (p<0.001), with higher BGLs being associated with greater mortality among non-diabetic than among diabetic patients. Among non-diabetic patients, the lowest mortality rate (3.0%) was in people with a BGL of 4.0-5.9 mmol/l. Compared with this group, patients with a BGL of 8.0-9.9 mmol/l had increased mortality rate (7.6%, HR 1.56, 95% CI 1.03-2.35, p=0.04, after adjustment for age and sex). The risk increased further at higher glucose levels. In the cohort with diagnosed diabetes, the increase in mortality rates at higher BGL bands was not significant.

CONCLUSIONS/INTERPRETATION: Among people who do not have diabetes, even modest degrees of hyperglycaemia on hospital admission are associated with increased mortality.