‘Gastric’ hypoglycaemia – an important concept in diabetes management

Abstract

The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) and UK Prospective Diabetes Studies (UKPDS) have established that both the development and progression of the microvascular (i.e. neuropathy, nephropathy and retinopathy), and probably macrovascular (i.e. cardiovascular disease), complications of type 1 (insulin-dependent) and type 2 (non-insulin dependent) diabetes mellitus are related to average glycaemic control, as assessed by measurement of glycated haemoglobin. This evidence provides a persuasive rationale for the widespread use of intensive therapy for diabetes directed at the normalization of glycaemia. For example, in the recently reported DCCT/EDIC study which involved type 1 patients, a period of intensive , as opposed to conventional , therapy for a mean period of 6.5 years during the DCCT study (i.e. between 1983 and 1993) was associated with a reduction in the risk of a subsequent (i.e. between 1994 and 2005) cardiovascular event of 42%. Hence, a major goal in treating diabetes is to achieve blood glucose levels as close as possible to the normal, fasting, range. This is compatible with the American Diabetes Association recommendation of a target glycated haemoglobin of <7.0%, which may in fact be conservative given that a specific healthy glycaemic threshold has hitherto not been demonstrated. To achieve current targets, the majority of type 2 patients will require treatment with insulin within 10 years of the diagnosis of diabetes. In practice, however, glycaemic targets are not often met in either type 1 or type 2 patients. There is a natural reluctance to initiate insulin therapy in type 2 patients because of the potentially deleterious consequences of insulininduced hypoglycaemia, especially in those patients whose ability to recognize impending hypoglycaemia is impaired. In the DCCT study, the reduction in microvascular complications seen in the intensive care group was accompanied by a threefold increase in the rate of severe hypoglycaemia. Effective management of recurrent hypoglycaemia is, of course, dependent on the correction of the underlying cause(s), which include excessive insulin dosage, inadequate carbohydrate intake, psychiatric disorders, various endocrinopathies, coeliac disease and vomiting (whether self-induced or associated with gastroparesis). However, in a substantial minority of patients a cause is not clearly identifiable. The interesting study by Lysy et al. reported in this issue of the Journal indicates that delayed gastric emptying represents a significant risk factor for hypoglycaemia in insulin-treated type 1 and type 2 diabetes. The authors evaluated gastric emptying in 31 insulin-treated patients who had recurrent episodes of hypoglycaemia early in the postprandial period. Gastric emptying of a scrambled egg meal was significantly slower when compared to a control group of patients with diabetes who did not have recurrent hypoglycaemia; in about 30% of patients, the magnitude of the delay in emptying was marked, even though none of them reported upper gastrointestinal symptoms such as nausea or bloating. Strengths of the study include the relatively large number of patients and the prospective design, although demographic differences (e.g. in age Address for correspondence Prof Michael Horowitz, Discipline of Medicine, University of Adelaide, Royal Adelaide Hospital, North Terrace, Adelaide, SA 5000, Australia. Tel: 61 8 8222 4327; fax: 61 8 8223 3870; e-mail: michael.horowitz@adelaide.edu.au Received: 11 April 2006 Accepted for publication: 11 April 2006 Neurogastroenterol Motil (2006) 18, 405–407 doi: 10.1111/j.1365-2982.2006.00804.x