An analysis of the relationship between Glasgow Coma Scale score and plasma glucose level according to the severity of hypoglycemia

BACKGROUND The Glasgow Coma Scale (GCS) score of an individual with hypoglycemia is expected to be low due to an insufficient glucose supply to the brain. However, we sometimes encounter hypoglycemic patients with high GCS scores. This study was undertaken to analyze the relationship between the GCS score and the plasma glucose level. METHODS Among the patients with neurological impairments admitted to our institution between October 1, 2010 and March 31, 2013, the cases of 41 hypoglycemic patients were examined in this retrospective cohort study. The defined plasma glucose level for mild hypoglycemia was 41-60 mg/dL, that for moderate hypoglycemia was 21-40 mg/dL, and that for extreme hypoglycemia was below 20 mg/dL. We divided the patients into two groups: those with mild hypoglycemia (n = 14) and those with moderate/extreme hypoglycemia (n = 27). We compared the two groups' physiological data and assessed the relationship between the GCS score and the plasma glucose level by Spearman rank correlation (ρ), the significance of which was determined by Spearman's rank sum test. We used the Mann-Whitney U-test and the chi-square (χ (2)) test to test for differences between the two groups when appropriate. RESULTS Three hundred twenty-six patients with neurological impairments were admitted during the study period, and 41were eligible hypoglycemic patients. The GCS scores of the 14 patients with mild hypoglycemia were significantly higher than those of the 27 patients with moderate or extreme hypoglycemia (median score 12, range 7-15 vs. 10, 3-15, p = 0.0367). There were no significant differences in physiological data (including autonomic symptoms) between the two groups. Spearman's rank sum test was 0.491 in the total group of 41 hypoglycemic patients, 0.053 in the mild hypoglycemic patients, and 0.493 in the moderately or extremely hypoglycemic patients. CONCLUSIONS The relationship between the GCS score and the plasma glucose level differed according to the severity of hypoglycemia. Even when a patient has a high GCS score, careful assessment of differential diagnosis should be conducted and the possibility of hypoglycemia should be considered in light of his or her neurogenous symptoms.