ABSTRACT

　Type 1 diabetes patients often suffered from exercise-induced hypoglycemia especially, nocturnal and delayed onset of hypoglycemia after exercise. In the present study, we characterized potential mechanisms for the development of delayed onset of exercise-induced hypoglycemia in type 1 diabetes by performing animal studies. We assessed the blood glucose levels and glucose metabolic pathway activation over time in streptozotocin (STZ) injected rats, STZ rats with exercise (STZ+EX), and control rats with exercise (CON+EX).Moreover, samples were taken at 1h, 3h and 5h after exercise in three groups, and was used for microarray analysis. Although blood glucose levels of STZ rats and CON+EX rats did not differ significantly before and after exercise (0h to 5h), the blood glucose levels of STZ+EX rats were significantly lower than those of STZ group at 3h (P<0.05). In skeletal muscles, Akt phosphorylation level and GLUT4 translocation were significantly increased at 1 h in both CON and STZ groups and were lowered to negligible levels within 3h. In contrast, in the STZ+EX group, Akt phosphorylation, and GLUT4 translocation was maintained by 5h, indicating sustained glucose metabolism in STZ+EX group. In microarray analysis, 447 genes of insulin signaling and 79 genes of type1 diabetes were found in this study, and selected 3 genes which may concern GLUT4 regulation, especially Oncostatin M (Osm) and signal transducer and activator of transcription 3 (STAT3) were increased at 3h and 5h after exercise in STZ+EX group. In summary, we showed that a single bout of aerobic exercise induced prolonged enhancement of GLUT4 translocation may be involved in the induction of hypoglycemia.

DESCENTE SPORTS SCIENCE Vol.38/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE