Type II (non-insulin-dependent) diabetes may be associated with impaired cognitive function. A detailed search of the literature has identified 19 controlled studies in which cognitive function in type II diabetes has been examined. The studies vary widely with respect to the nature of the diabetic populations studied and the psychological tests used. Thirteen studies demonstrated that the diabetic individuals performed more poorly in at least one aspect of cognitive function. The most commonly affected cognitive ability was verbal memory. Psychomotor ability and frontal lobe function were affected less consistently. The remaining six studies showed no differences in cognitive ability between subjects with type II diabetes and nondiabetic control subjects, but none had adequate statistical power to detect a between-group difference in cognitive ability of 0.5 of a standard deviation (a medium effect size). These findings are consistent with type II diabetes being associated with an increased risk of cognitive dysfunction. However, the widespread differences in methodology between the studies should lead to a cautious interpretation of their conclusions. The etiology of any cognitive decrement in type II diabetes is likely to result from an interaction between metabolic abnormalities intrinsic to diabetes, diabetes-specific complications, and other diabetes-related disorders.

305A cute hypoglycemia induces cognitive dysfunction as a consequence of neuroglycopenia. Cognitive functions that deteriorate include simple and choice reaction times, speed of arithmetic calculation, verbal fluency, color identification, trail making and digit symbol test perf o rmance, digit span, and other short -t e rm m e m o ry indices (1). Mood states are also a ffected by mild hypoglycemia, which causes a reduction in levels of energ e t i c a rousal and an increase in tense arousal (2).Acute hypoglycemia can pro v o k e l o n g e r-t e rm effects, even after norm oglycemia has been re s t o red. In nondiabetic and diabetic subjects, the symptomatic and n e u roendocrine responses to acute hypoglycemia are diminished after antecedent (episodic) hypoglycemia that has occurre d within the previous 72 h (3-7). Indeed, the catecholamine response to hypoglycemia may take between 6 days and 4 weeks to re t u rn to a normal magnitude (8). The e ffects of acute mild hypoglycemia on cognitive functions appear to be less pro l o n g e d , in that cognitive function recovers within 1 h of the restoration of normoglycemia (9-13). The long-term effects of acute hypoglycemia on other mental states such as mood and general well-being have received less attention. Mood changes during acute hypoglycemia persist for at least 30 min after restoration of normoglycemia (2), where a s relatively brief nocturnal hypoglycemia is not associated with any cognitive impairment the following morning (14,15) but is associated with greater levels of fatigue in response to exercise the next day (15).S e v e re hypoglycemia, which is defined as an episode requiring external assistance for re c o v e ry, causes pronounced neuro g l ycopenia that results in a profound degree of cognitive dysfunction and (rarely) can cause permanent neurological impairm e n t (16-18). Fort u n a t e l y, most patients appear to make a complete and rapid re c o v e ry after normoglycemia is re s t o red, although anecdotal observation suggests that some patients have cognitive impairment for m o re protracted periods. Exposure to repeated episodes of severe hypoglycemia may possibly result in persistent cognitive i m p a i rment in some patients (19-23), although this has been disputed (24,25).No previous studies have examined the timing of re c o v e ry of cognitive function and mood after a single episode of severe hypoglycemia. Delayed re c o v e ry of cognitive functions after severe hypoglycemia could have potentially important effects on perf o rmance of activities such as work or driving. The purpose of the present study was to examine the temporal changes in mood states and cognitive functions after a single spontaneous episode of severe hypoglycemia in people with insulin-treated diabetes. O B J E C T I V E -Acute hypoglycemia in humans impairs cognitive functions and alters mood states. The time re q u i red for cognitive functions and moods to re t u rn to normal after an acute episode of severe hypoglycemia is unknown.RESEARCH DESIGN AND METHO...

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