Introduction
Routine HbA1c testing on admission of inpatients presenting with acute coronary syndrome (ACS) presents a unique opportunity for diagnosing pre-existing dysglycaemia without the limitations of stress-induced hyperglycaemia.
Objectives
We aimed to determine the prevalence of pre-existing dysglycaemia in inpatients presenting with ACS and its association with clinical outcomes, including acute pulmonary oedema (APO), recurrent ACS and, all-cause mortality at 12 months.
Methods
As part of the Austin Health Diabetes Discovery Initiative, routine HbA1c testing was undertaken on all inpatients aged ≥54 years admitted with ACS if none was available within the preceding 90 days. Patients were categorised into those with diabetes (prior diagnosis or HbA1c ≥ 6.5%, ≥48mmol/mol), pre-diabetes (HbA1c 5.7-6.4%, 39-46mmol/mol) and no diabetes (HbA1c <5.6%, <38mmol/mol).
Results
Between July 2013 and July 2015, 847 consecutive patients were admitted with ACS. 313 (37%) inpatients had diabetes, 312 (37%) had pre-diabetes and 222 (25%) had no diabetes. After adjusting for age, sex, smoking status and previous myocardial infarction, diabetes, as opposed to no diabetes, was associated with a higher risk of APO (OR 2.60, P<0.01), longer length of stay (LOS) (IRR 1.18, P=0.02) and, higher risk of 12-month ACS recurrence (OR 1.86, P<0.05). Pre-diabetes was not a statistically significant marker of adverse clinical outcomes. However, analysed as a continuous variable, HbA1c was associated with an increased risk of APO (OR 1.28, P=0.002) and, longer LOS (IRR 1.05, P=0.03).
Conclusions
In our study, three-quarters of all inpatients aged ≥54 years admitted with ACS had pre-existing dysglycaemia. Inpatients with diabetes were at increased risk of developing APO and subsequent 12-month ACS recurrence. Increases in HbA1c, even in the pre-diabetic range, was associated with a higher risk of APO and longer LOS. Randomised studies would be necessary to determine if improving dysglycaemia in ACS patients improves longer term outcomes.