Hypoglycaemia in Clinical Diabetes

CONSEQUENCES OF HYPOGLYCAEMIA 205of mild ventricular atrophy in those with early onset diabetes. None of the findings wererelated to the presence of microvascular disease or diabetes duration, suggesting that thecumulative effects of hyperglycaemia were unlikely to be causative. However, no definite linkwas confirmed between exposure to severe hypoglycaemia and any of these defects, althoughthe study was limited by retrospective reporting of the history of preceding hypoglycaemiaover a long period of time (Ferguson et al., 2005). Another study did not find a differencein tests of cognitive function over a period of 18 months in 142 patients taking part in astudy examining the impact of intensive therapy versus usual care (Wysocki et al., 2003).The study group had a wide age range from 6–15 years and data from younger childrenwere not analysed separately.Although there are methodological problems in designing studies to assess long-termcognitive function in children who have an ongoing chronic disorder, these studies do raiseanxieties. It is felt that until hypoglycaemia can be reliably avoided, glycaemic control shouldbe less intensively managed in younger children to avoid the risk of severe hypoglycaemia.This would put younger children at greater risk of developing the long-term microvascularcomplications of diabetes in an attempt to avoid the possible cognitive defects that may beassociated with recurrent hypoglycaemia.Hypoglycaemic HemiplegiaThis is a rare complication of acute hypoglycaemia in which the patient recovers fromthe hypoglycaemia with a transient hemiparesis lasting no more than 24 hours. Whenneuroimaging is performed it is rare to find an abnormality. There is no evidence of anysevere sequelae to this neurological manifestation of severe neuroglycopenia (Pocecco andRonfani, 1998).Fear of HypoglycaemiaBoth the children with diabetes and their parents worry about the prospect of a severe episodeof hypoglycaemia (Gold et al., 1997; Clarke et al., 1998; Gonder-Frederick et al., 1997;Marrero et al., 1997; Nordfelt and Ludvigson, 2005) (see Chapter 14). In one study severehypoglycaemia caused more fear than the prospect of an episode of diabetic ketoacidosis(Nordfelt and Ludvigson, 2005). Although there is little evidence that this modifies behaviourto attempt hypoglycaemia avoidance, such as relaxing glycaemic control or eating moresnacks, the adverse effects on quality of life should not be underestimated (Gold et al.,1997).Prediction of Nocturnal HypoglycaemiaOvernight glucose profiles have been shown to be extremely variable. As a result studies ofovernight hypoglycaemia have been unable to provide a ‘safe’ glucose value with which togo to bed. What is more useful is the fasting blood glucose concentration on the followingmorning. One study showed that the median fasting blood glucose at 07:00 hours wassignificantly lower following hypoglycaemia than a night with no hypoglycaemia (3.7[1.4–10.6] versus 8.5 [3.8–19.2] mmol/l, p = 000001) (Matyka et al., 1999a) (Figure 9.2).