Immobilization in diabetic rats results in altered glucose tolerance A model of reduced locomotion/activity in diabetes

Aims Type 2 Diabetes Mellitus affects more than 350 million people worldwide. This metabolic disorder is characterized by insulin resistance, β-cell dysfunction and elevated hepatic glucose output. Patients with diabetes are hospitalized frequently (3-fold greater) and with longer admissions (30% longer) than the non-diabetic subjects. The aim of the present study was to investigate the impact of bed rest on the metabolic changes in type 2 diabetes mellitus, with particular interest in skeletal muscle mass and function and metabolism. Methods and results 13wk old male Zucker diabetic fatty (ZDF) rats were randomly divided into two groups: control (ZDF-Con) and cage-immobilized animals (ZDF-Cage) for 28 consecutive days in a space-restricted cage. The Area Under the Curve (AUC) values for plasma glucose concentration in ZDF-Cage rats were significantly increased (approximately 4-fold as compared with ZDF-Con rats). GLUT4 gene expression in red soleus muscle of ZDF-Cage animals was reduced 2.5-fold in comparison with ZDF-Con rats. Although no apparent changes were observed either in fasting plasma glucose or insulin levels, a trend towards an increase in the HOMA-IR index and decreased levels of plasma adiponectin (-30%) were observed in ZDF-Cage animals. Moreover, ZDF-Cage rats did not lose muscle mass and force but performed a reduced total physical activity level (-22%). Conclusions The present study results suggests that 28 days of immobilization (in a space-restriction model) significantly impaired glucose tolerance with concomitant reduced plasmatic adiponectin levels and GLUT4 expression in soleus muscle of type 2 diabetic rats.