COGNITIVE FUNCTION, INSULIN-DEPENDENT DIABETES AND HYPOGLYCEMIA

A series of seven psychometric tests, to evaluate mental concentration and the ability to retain selective attention, lexical fluency, wordlist memorizing and psychomotor speed, was performed on 25 non-diabetic control subjects and 55 insulin-dependent diabetes (IDD) patients of similar social background and professional status. When tested, none of the diabetics was hypoglycaemic and these patients were divided into two groups: Group I: 30 IDD patients unaware of hypoglycaemia, and experiencing frequent and severe episodes of hypoglycaemia. Group II: 25 IDD patients aware of hypoglycaemia. Groups I and II had experienced the disease for the same period of time (17 +/- 13 vs. 14 +/- 11 years, respectively) and they had similar HbA1c levels (7.14 +/- 1.25% vs. 8.6 +/- 1.88%, respectively) and degenerative complications. Compared with the scores of the controls, the Group I scores were lower in four tests: trail-making part A (psychomotor speed; P < 0.001) and part B (retaining selective attention: P < 0.01). lexical fluency (P < 0.01) and Rey auditory-verbal learning test (wordlist learning; P < 0.05). Group II scores were lower in two tests: trail-making part A (P < 0.01) and part B (P < 0.05). In word memorizing, the performance of Group I was inferior to that of Group II (P < 0.05). In general, these psychometric tests showed that IDD scores were lower than those of the controls, with an average of 67% for Group II and 80% for Group I. Chronic hyperglycaemia and severe hypoglycaemia may have a deleterious effect on cognitive performance. In particular, several severe episodes of hypoglycaemia could be responsible for permanent memory impairment.