Abstract

Objective: To examine the effects of acute insulin-induced hypoglycemia on spatial cognitive abilities in adult humans with type 1 diabetes.

Research Design and Methods: Sixteen adults with type 1 diabetes underwent two counterbalanced experimental sessions: euglycemia (blood glucose 4.5mmol/l; 81mg/dl) and hypoglycemia (2.5mmol/l; 45mg/dl). Arterialized blood glucose levels were maintained using a hyperinsulinemic glucose clamp technique. During each session, subjects underwent detailed assessment of spatial abilities from the Kit of Factor-Referenced Cognitive Tests, and two tests of general cognitive function.

Results: Spatial ability performance deteriorated significantly during hypoglycemia. The Hidden Patterns, Card Rotations, Paper Folding, and Maze Tracing tests were all impaired significantly (p≤0.001) during hypoglycemia, as was the Cube Comparisons test (p=0.03). The Map Memory test was not significantly affected by hypoglycemia.

Conclusions: Hypoglycemia is a common side-effect of insulin therapy in people with type 1 diabetes, and spatial abilities are of critical importance in day-to-day functioning. The deterioration in spatial abilities observed during modest experimental hypoglycemia provides novel information on the cerebral hazards of hypoglycemia that has potential relevance to everyday activities.