Mechanism of insulin resistance in a rat model of kidney disease and the risk of developing type 2 diabetes

Chronic kidney disease is associated with homeostatic imbalances such as insulin resistance. However, the underlying mechanisms leading to these imbalances and whether they promote the development of type 2 diabetes is unknown. The effect of chronic kidney disease on insulin resistance was studied on two different rat strains. First, in a 5/6(th) nephrectomised Sprague-Dawley rat model of chronic kidney disease, we observed a correlation between the severity of chronic kidney disease and hyperglycemia as evaluated by serum fructosamine levels (p < 0.0001). Further, glucose tolerance tests indicated an increase of 25% in glycemia in chronic kidney disease rats (p < 0.0001) as compared to controls whereas insulin levels remained unchanged. We also observed modulation of glucose transporters expression in several tissues such as the liver (decrease of approximate to 40%, p <= 0.01) and muscles (decrease of approximate to 29%, p <= 0.05). Despite a significant reduction of approximate to 37% in insulin-dependent glucose uptake in the muscles of chronic kidney disease rats (p <= 0.0001), the development of type 2 diabetes was never observed. Second, in a rat model of metabolic syndrome (Zucker Lepr (fa/fa)), chronic kidney disease caused a 50% increased fasting hyperglycemia (p < 0.0001) and an exacerbated glycemic response (p < 0.0001) during glucose challenge. Similar modulations of glucose transporters expression and glucose uptake were observed in the two models. However, 30% (p < 0.05) of chronic kidney disease Zucker rats developed characteristics of type 2 diabetes. Thus, our results suggest that downregulation of GLUT4 in skeletal muscle may be associated with insulin resistance in chronic kidney disease and could lead to type 2 diabetes in predisposed animals.