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.