Purpose: To identify the population susceptible to reactive hypoglycemia and explain the possible reasons for their susceptibility.
Methods: Ninety-four patients were divided into normal weight, overweight and obese groups before a 75-gram prolonged oral glucose tolerance test (POGTT). The incidence of reactive hypoglycemia (blood glucose ≤ 3.1 mmol/L or 55 mg/dL at points of 0– 4 hours) was compared among three groups, and blood glucose and insulin levels were monitored simultaneously from 0 - 4 hours to assess the level of insulin resistance and insulin sensitivity. Furthermore, the degree of insulin resistance among three groups and within each subgroup (whether hypoglycemia events occurred) was compared.
Results: Among the three groups, the incidence of hypoglycemia was significantly different at 3 (P =0.033) and 4 hours (P =0.020). At 4 hours, the incidence of reactive hypoglycemia in the obese group was approximately 3 times that in the normal weight group. The insulin level in obese group at 4 hours was nearly 4 times higher than that in normal group, and the same result also exists in the same subgroup of different groups. In addition, the hypoglycemia subgroup of obese group had higher insulin level than non-hypoglycemia (P=0.000). The homeostasis model assessment of insulin resistance index increased with increasing BMI among the three groups (P =0.000), while the Matsuda index decreased (P =0.000). The comparison of the homeostasis model assessment of insulin resistance index between subgroups in each group showed that the P  values were 0.021, 0.038 and 0.085, successively, and the P  values for the Matsuda index were 0.019, 0.013 and 0.119, respectively.
Conclusion: Obese people has higher rate of reactive hypoglycemia than other groups in POGTT, in which insulin resistance may play an important role. But patients who are evaluated for reactive hypoglycemia need to be observed for at least 3 or 4 hours.
Keywords: reactive hypoglycemia, prolonged oral glucose tolerance test, insulin resistance, low-carb ketogenic diet