This guideline covers the role of intensive insulin therapy in managing hyperglycaemia within the first 48 hours in people admitted to hospital for acute coronary syndromes (ACS). Intensive insulin therapy is defined as an intravenous infusion of insulin and glucose with or without potassium. For the purposes of this guideline, hyperglycaemia is defined as a blood glucose level above 11 mmol/litre. This definition was based on the expert opinion of the Guideline Development Group (GDG) and was agreed by consensus.
ACS encompass a spectrum of unstable coronary artery disease, ranging from unstable angina to transmural myocardial infarction. All forms of ACS begin with an inflamed and complicated fatty deposit (known as an atheromatous plaque) in a blood vessel, followed by blood clots forming on the plaque. The principles behind the presentation, investigation and management of these syndromes are similar, but there are important distinctions depending on the category of ACS.
Hyperglycaemia is common in people admitted to hospital with ACS. Recent studies found that approximately 65% of patients with acute myocardial infarction who were not known to have diabetes had impaired glucose regulation when given a glucose tolerance test.
Hyperglycaemia at the time of admission with ACS is a powerful predictor of poorer survival and increased risk of complications while in hospital, regardless of whether or not the patient has diabetes. Despite this, hyperglycaemia remains underappreciated as a risk factor in ACS and is frequently untreated.
Persistently elevated blood glucose levels during acute myocardial infarction have been shown to be associated with increased in-hospital mortality, and to be a better predictor of outcome than admission blood glucose. Management of hyperglycaemia after ACS is therefore an important clinical issue.
A wide range of national guidance is available for the care of people with diabetes in hospital with relevance to ACS patients. For example the NHS Institute for Innovation and Improvement ThinkGlucose toolkit recommends that all patients with ACS and known diabetes are referred to the inpatient diabetes team.
The guideline does not make recommendations on drug dosage; prescribers should refer to the 'British national formulary' for this information. The guideline also assumes that prescribers will use a drug's summary of product characteristics to inform decisions made with individual patients.