Hypoglycaemia in Clinical Diabetes

12 Mortality, CardiovascularMorbidity and Possible Effectsof Hypoglycaemia on DiabeticComplicationsMiles Fisher and Simon R. HellerINTRODUCTIONFor patients with type 1 diabetes, insulin-induced hypoglycaemia is one of the most fearedconsequences of the disorder (Pramming et al., 1991). It is the major factor that restrainsmany patients from pursuing intensive insulin therapy and trying to achieve the levels of strictglycaemic control that are necessary to prevent the development of diabetic complications.Some fear the immediate lack of self control which can accompany the impairment ofcognitive function during acute hypoglycaemia. Others are embarrassed by the dependenceon other people for assistance during an episode of severe hypoglycaemia. Many patientsshare the worries expressed by some diabetes healthcare professionals about the possiblelong-term effects of recurrent hypoglycaemia on the brain (see Chapter 13).An additional factor which may dissuade many patients from improving their glycaemiccontrol is the fear of dying during an episode of hypoglycaemia, especially when lowblood glucose occurs during sleep. These anxieties may be shared by the patient’s relativeswho may have witnessed previous episodes of nocturnal hypoglycaemia or convulsions,about which the patient has no recollection. Fear of hypoglycaemia was heightened in the1980s by the publicity that surrounded the possible adverse effects of human insulin, andin particular the knowledge that some young people with type 1 diabetes had died suddenlyand unexpectedly, the so-called ‘dead in bed syndrome’ (Campbell, 1991).It would be wrong for healthcare professionals to dismiss such fears as irrational. Manyprofessionals will have first- or second-hand experience of the sudden death of a patientwith type 1 diabetes in circumstances that have implicated acute hypoglycaemia. Thischapter examines the epidemiology and causes of death from hypoglycaemia in patients withdiabetes, including those risk factors that appear to be associated with sudden death. The‘dead in bed syndrome’ is explored in detail, and comparisons drawn with other syndromesof sudden death in people who do not have diabetes. Putative mechanisms and risk factorsfor sudden death are described. Hypoglycaemia may also cause significant cardiovascularmorbidity in people with diabetes, and the effects on heart disease and cardiovascularHypoglycaemia in Clinical Diabetes, 2nd Edition.© 2007 John Wiley & Sons, LtdEdited by B.M. Frier and M. Fisher