Associations of fluctuations in blood glucose and insulin with hypoglycemic symptoms

Associations between fluctuations in blood glucose levels and medically unexplained symptoms, such as palpitations, numbness in the extremities, dizziness, and drowsiness, have been a topic of debate for an extended period; however, consensus remains elusive. We therefore examined the associations of blood glucose and insulin levels with symptoms by performing a 5 h glucose tolerance test in patients without diabetes with complaints. A total of 139 (54 men and 85 women, mean age 35.4 years) were included in this study. Blood glucose and insulin levels were measured before and at 15, 30, 60, 90, 120, 150, 180, 240, and 300 min after a 10-h fast and 75 g glucose load. The insulin index was used to divide the participants into early, intermediate, and delayed insulin secretion groups. Hypoglycemic symptoms (neuroglycopenic: warmth, drowsiness, weakness, fainting, decreased thinking ability, and dizziness) and autonomic symptoms (neurogenic: palpitations, cold sweats, anxiety/nervousness, tremors, hunger, and tingling) were evaluated separately. Hypoglycemia (< 70 mg/dL (3.9 mmol/L)) occurred at 240-300 min in 92% of all patients, with hypoglycemic and autonomic symptoms. Hypoglycemic symptoms increased over time and were highest at 240 min, while autonomic symptoms decreased significantly for 15 min and increased at 240 and 300 min. Although hypoglycemic symptoms were not significantly different among the early, intermediate, and delayed secretion groups, the incidence rates of autonomic symptoms were higher in the early insulin secretion group than in the other groups at 30-60-90 min. The characteristics of the early insulin secretion group suggested that symptoms were associated with not only blood glucose levels but also the timing of insulin secretion. Further studies are needed to determine whether dietary interventions tailored to insulin secretion profiles can alleviate these symptoms.