Hypoglycaemia in Clinical Diabetes

256 HYPOGLYCAEMIA IN TYPE 2 DIABETES AND IN ELDERLY PEOPLErate of severe hypoglycaemia requiring emergency medical intervention was similar in thesegroups (Leese et al., 2003). All episodes of severe hypoglycaemia requiring input from theemergency medical services in one year were identified. A total of 160 people with diabetesrequired treatment for 244 episodes of severe hypoglycaemia. Emergency treatment wasrequired for 7.1% of those with type 1 diabetes, 7.3% of those with insulin-treated type 2diabetes and 0.8% of people taking oral antidiabetic agents.In a different prospective survey in the same region of Tayside, the occurrence of hypoglycaemiawas monitored over a period of one month in a cohort of 267 people withinsulin-treated diabetes (both type 1 and type 2) (Donnelly et al., 2005). The prevalence ofall forms of hypoglycaemia in the group with insulin-treated type 2 diabetes was 45% withan incidence of 16.4 episodes per patient per year, compared to an incidence of 42.9 episodesper patient per year in type 1 diabetes. The incidence of severe hypoglycaemia was 0.35episodes per patient per year in the group with type 2 diabetes and 1.15 episodes per patientper year in those with type 1 diabetes. The figures for the incidences were extrapolated fromprospective data collected over one month but these calculated rates for people with type 1diabetes are consistent with those recorded in other European studies (Pramming et al., 1991;MacLeod et al., 1993; ter Braak et al., 2000; Pedersen-Bjergaard et al., 2004), suggestingthat the data collected were representative of the annual event rate. In this study, only 10%of the group with type 1 diabetes experiencing severe hypoglycaemia required emergencyservice treatment compared to one in three of the group with type 2 diabetes. Thus thefrequency of severe hypoglycaemia recorded in people with type 2 diabetes was higher thananticipated and their need to enlist the help of the emergency services was greater than inthose with type 1 diabetes.CONCLUSIONS• Ageing modifies the counterregulatory and symptomatic responses to hypoglycaemia.• In older people, effective self-treatment of hypoglycaemia may be compromised by theclose proximity of the glycaemic thresholds for the onset of symptoms and cognitivedysfunction, which occur almost simultaneously.• In type 2 diabetes, counterregulatory responses to hypoglycaemia commence at higherblood glucose levels than those observed in non-diabetic adults or in people with type 1diabetes, and this may have a protective effect. When insulin therapy is introduced andHbA 1c is reduced, these thresholds are shifted to lower blood glucose levels.• With progressive insulin deficiency, people with type 2 diabetes develop counterregulatoryhormonal deficiencies and impaired symptomatic awareness, similar to the acquiredhypoglycaemia syndromes of type 1 diabetes.• Hypoglycaemia in type 2 diabetes occurs most frequently with insulin therapy, butsulphonylurea-induced hypoglycaemia is also a significant but under-estimated problem.• Although less common than in type 1 diabetes, the frequency of hypoglycaemia in insulintreatedtype 2 diabetes rises progressively with increasing duration of insulin treatment.• People with insulin-treated type 2 diabetes are more likely to require the assistance ofemergency medical services to treat severe hypoglycaemia than those with type 1 diabetes.