Anxiety Constitutes an Early Sign of Acute Hypoglycemia

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).

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).

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.

The main effect of acute hypoglycemia is anxiety, which may be considered an early sign of hypoglycemia in an allostatic process.