Quality Standards for Diabetes Care Toolkit

Definitions

Severe hypoglycaemia

Severe hypoglycaemia is defined as any episode of hypoglycaemia requiring external help (Leese et al 2003).

Introduction

Achieving glycaemic control as close to normal levels as possible is recommended for most people with diabetes with type 1 or type 2 diabetes to minimise the risk of complications (Diabetes Control and Complications [DCCT] Research Group 1997; United Kingdom Prospective Diabetes Study 1998). The increased treatment costs of achieving this are offset by the reduced cost of treating complications and an improved quality of life (Gray et al 2000). Hypoglycaemia, however, is the principal problem associated with strict glycolic control (DCCT Research Group 1997).
Hypoglycaemia is a common side effect of insulin therapy in diabetes, particularly in people with type 1 diabetes. Episodes of mild hypoglycaemia (self-treated) can occur frequently (1–2 episodes per week) (Pramming et al 1991; Pramming et al 2000) while severe hypoglycaemia affects up to 30% of people with type 1 diabetes annually (EURODIAB IDDM Complications Study Group 1994; ter Braak et al 2000). In the DCCT (1997), overall rates of severe hypoglycaemia were 61.2 per 100 patient-years versus 18.7 per 100 patient-years in the intensive and conventional treatment groups respectively, with a relative risk (RR) of 3.28. The relative risk for coma and/or seizure was 3.02 for intensive therapy. According to Leese et al (2003), most episodes of severe hypoglycaemia are treated effectively at home or at work by friends, relatives, or colleagues and do not require the assistance of the emergency medical services. Therefore, episodes presenting to and treated in the hospital emergency department are recognised as representing the ‘tip of the iceberg’ (Potter et al 1982). In their population-based study of health service resource use, Leese et al reported that nearly 1 in 14 people with insulin-treated diabetes experiences one or more episodes of severe hypoglycaemia annually that requires the urgent therapeutic intervention of health service personnel. Although severe hypoglycaemia is more common in type 1 diabetes, insulin treatment rather than the type of diabetes was the predominant feature.
In type 2 diabetes, the risk of hypoglycaemia with sulfonylurea therapy is often underestimated and prolonged due to the duration of the action of the tablets. People at particular risk are patients with renal impairment or the elderly (Joint British Diabetes Societies for Inpatient Care Group 2010). According to the Joint British Diabetes Societies (2013), hypoglycaemia is associated with increased morbidity and mortality, leading to coma, hemiparesis and seizures. ‘If the hypoglycaemia is prolonged the neurological deficits may become permanent. Acute hypoglycaemia impairs many aspects of cognitive function, particularly those involving planning and multitasking. The long term effect of repeated exposure to severe hypoglycaemia is less clear’ (p 10).
In the DCCT approximately 30% of patients in both the treatment groups experienced a second episode within the four months following the first episode of severe hypoglycaemia. Within each treatment group, the number of prior episodes of hypoglycaemia was the strongest predictor of the risk of future episodes, followed closely by the current HbA1c value. Those found to be more at risk included males, adolescents, and people with no residual C-peptide or with a prior history of hypoglycaemia. Leese et al reports that people who were older, had a longer duration of diabetes, or a higher HbA1c were more at risk. Those with impaired awareness of hypoglycaemic symptoms are at an increased risk of experiencing severe hypoglycaemia. ‘Impaired awareness of hypoglycaemia (IAH) is an acquired syndrome associated with insulin treatment. IAH results in the warning symptoms of hypoglycaemia becoming diminished in intensity, altered in nature or lost altogether. This increases the vulnerability of affected individuals of progression to severe hypoglycaemia (JBDS 2013, p 9).’
IAH prevalence is seen more commonly in type 1 than in type 2 diabetes, with a growing prevalence as the duration of diabetes increases (JBDS 2013).
Hypoglycaemia is the commonest diabetes-related contact with ambulance crew and Accident and Emergency (A&E) in the UK (Joint British Diabetes Societies for Inpatient Care Group 2013). One study investigating hypoglycaemia-related ambulance callouts revealed many people with diabetes did not know how to use glucagon, nor were they aware of the warning signs of hypoglycaemia, and they had not had a specific education session with a doctor or nurse about hypoglycaemia and how to avoid it in the previous year or at any time. The cost to society through ambulance attendance and possible transfer to secondary care, and associated cost through days off work and lost productivity was estimated to be £240,800 per 1000 ambulance attendances. Improved support and enhanced education and understanding of hypoglycaemia would translate into reduced costs and significant savings (Joint British Diabetes Societies for Inpatient Care Group 2013).
Follow-up care after an episode of hypoglycaemia should occur, preferably by a health care professional with specialist knowledge of diabetes. In particular, patients with reduced awareness of hypoglycaemia need intensive input from a specialist diabetes team (Brackenridge et al 2006). Most studies affirm patients that are scheduled or seen for post-hospital follow-up are less likely to be readmitted (Balaban et al 2008). The optimal time interval between discharge and the first follow-up is not known as many factors contribute to the decision, including severity of the disease process, perceived ability of the patient to provide adequate self-care, and psychosocial and logistical factors (Misky et al 2010).