Hospital admission secondary to hypoglycaemia in type 2 diabetes

Journal of Diabetes Nursing, March-April, 2002 by Vicky Johnston, Jo Howe, Melanie Davies

Introduction

There is an increasing awareness of the risk of hypoglycaemia in people with type 2 diabetes taking oral hypoglycaemic agents (OHAs), particularly the sulphonylureas. This paper reviews some of the relevant data and also presents data of admissions to a large teaching hospital secondary to hypoglycaemia over a 2-year period. A number of risk factors are identified and strategies to reduce risk in higher risk patients are presented. New products, insulin secretagogues and insulin analogues, hold promise in this respect.

Hypoglycaemia is one of the most common acute complications of diabetes. The common perception is that it is predominantly a problem associated with insulin treatment in people with type I diabetes. The risk of hypoglycaemia is increased as patients and healthcare professionals strive to achieve optimal glycaemic targets (DCCT, 1993).

Type 2 diabetes and hypos

However, the United Kingdom Prospective Diabetes Study (UKPDS, 1998) vividly demonstrated the problem of hypoglycaemia in people with type 2 diabetes taking either a sulphonylurea or insulin. In this study, patients in the intensive control group had significantly more hypoglycaemic episodes than those in the conventional group. Rates of major hypoglycaemic episodes per year were 0.7% with conventional treatment, 1% with chlorpropamide, 1.4% with glibenclamide and 1.8% with insulin therapy.

Sulphonylureas and hypos

There is an increasing awareness of problems with hypoglycaemia in patients with type 2 diabetes taking sulphonylureas. Jennings et al (1989) looked at the prevalence of hypoglycaemia in patients aged 40-65 years taking oral hypoglycaemic agents. Of 205 people attending a routine diabetes clinic, 20% of those taking sulphonylureas -- but none taking metformin alone -- reported symptoms of hypoglycaemia over the preceding six months. The prevalence of patients reporting hypoglycaemic symptoms increased with a lower mean [HbA.sub.1c].

Precipitating factors

In terms of data about hypoglycaemia precipitating hospitalisation in people with type 2 diabetes, there is increasing evidence regarding the role of sulphonylureas.

Sugarman (1991) evaluated the rates, causes and clinical features of hospitalisation associated with hypoglycaemia in a population with a high prevalence of type 2 diabetes in North America. During 26 125 person-years of follow-up, there were 126 hypoglycaemia-associated admissions related to diabetes in 109 patients. The hospitalisation rate was 4.7 per 1 000 person-years overall; but, when broken down for treatment, rates were 5.8 for chlorpropamide, 16 for glibenclamide and 9.1 for insulin.

After adjustment for age, the relative risk for hypoglycaemia-associated hospital admission in patients taking glibenclamide compared with patients taking chlorpropamide, was 2.8. Certainly, this study showed that hospitalisation secondary to hypoglycaemia was relatively common in subjects with type 2 diabetes and that sulphonylureas, particularly glibenclamide, are at least as likely, and maybe more likely than insulin to precipitate hospitalisation.

Risk factors

Further studies have identified risk factors that provoke drug-induced hypoglycaemia. These include increasing age, hepatic disease, renal disease, restricted food intake, intercurrent illness, e.g. sepsis or gastro-enteritis, and psychiatric illness (Seltzer, 1989; Teo and Ee, 1997). Use of concomitant medication can also increase the risk of hypoglycaemia; ACE inhibitors, aspirin and beta-blockers have been shown either to increase the risk of hypoglycaemia or mask the recognition of typical hypoglycaemic symptoms (Cryer and Gerich, 1985; Morris et al, 1997). It is well known in general that patients with type 2 diabetes are receiving more of these agents in order to reduce their cardiovascular risk, or to treat established cardiovascular disease.

Study aim

A study was carried out in a large teaching hospital examining admissions secondary to hypoglycaemia over a 2-year period, in order to determine the patients' treatment regime and to identify potential avoidable factors for admission.

Methods

The hospital, the Leicester Royal Infirmary, has approximately 1 200 inpatient beds and admits unselected acute medical emergency admissions on a daily basis. A recent audit showed that about 10% of inpatients in this hospital at any one time have diabetes; this figure is consistent with other inpatient surveys (Uchegbu et al, 2001).

Patient information was collected from the health authority database (which was cross-referenced with the clinical information system within the acute trust) and the A&E records. A standard proforma was used to collect basic demographic information, use of concomitant therapy and other laboratory data.

Results

Between April 1997 and March 1999, 83 admissions secondary to hypoglycaemia were recorded. Case notes were obtained for 75 (90%) of these admissions and fully reviewed.

Of these, 38 (5 1%) had type 2 diabetes. Thirteen of the reviews concern patients who were readmiited. Demographics are shown in Figure I.