Anxiety Constitutes an Early Sign of Acute Hypoglycemia

Introduction: Research in humans has identified a link between hypoglycemia and anxiety. The present study examined anxiety-like behaviors in rats that were subjected to hypoglycemia that was produced by an acute injection of insulin. Healthy female Wistar rats were subjected to a battery of tests to explore anxiety (elevated plus maze) and locomotion (open field test). Methods: The control (CT) group received 0.9% saline (3 mL/kg, p.o.). Three other groups received 50% glucose (3 mL/kg, p.o.), insulin (0.1 UI, s.c.), or insulin + glucose (normalized glycemia [NG] group). Results: Normal glycemic values were found in the CT and NG groups. Therefore, a single control (CT-NG) group was formed for statistical comparisons. The highest glycemic value was found in the glucose-induced hyperglycemia group. The lowest glycemic value was found in the insulin-induced hypoglycemia group. In the open field test, the most significant change was a higher number of rearings in the hypoglycemia group. In the elevated plus maze test, the CT-NG group and hyperglycemia groups exhibited similar behavior, whereas the hypoglycemia group spent a shorter time on the open arms and a longer time on the closed arms and had the highest Anxiety Index. Hyperglycemia is a typical characteristic of diabetes. Insulin normalizes glycemia. In the present study, insulin produced anxiety only when it produced hypoglycemia. Conclusion: The main effect of acute hypoglycemia is anxiety, which may be considered an early sign of hypoglycemia in an allostatic process.