Acute Hyperglycemia Alters Mood State and Impairs Cognitive Performance in People With Type 2 Diabetes

OBJECTIVE: To examine the effects of acute hyperglycemia on cognitive function and mood in people with type 2 diabetes. RESEARCH DESIGN AND METHODS: Twenty subjects with type 2 diabetes, median age 61.5 years (range 53.1-72.0), known duration of diabetes 5.9 years (range 2.8-11.2), BMI 29.8 kg/m2 (range 22.0-34.6), and HbA1c 7.5% (range 6.7-8.4) were studied. Treatment modalities varied from antidiabetic medications to insulin. A hyperinsulinemic glucose clamp was used to maintain arterialized blood glucose at either 4.5 (euglycemia) or 16.5 mmol/l (hyperglycemia) on two occasions in a randomized and counterbalanced fashion. Tests of information processing, immediate and delayed memory, working memory, and attention were administered, along with a mood questionnaire, during each experimental condition. RESULTS: Speed of information processing, working memory, and some aspects of attention were impaired during acute hyperglycemia. Subjects were significantly more dysphoric during hyperglycemia, with reduced energetic arousal and increased sadness and anxiety. CONCLUSIONS: During acute hyperglycemia, cognitive function was impaired and mood state deteriorated in a group of people with type 2 diabetes. These findings are of practical importance because intermittent or chronic hyperglycemia is common in people with type 2 diabetes and may interfere with many daily activities through adverse effects on cognitive function and mood.